437 results on '"free-radical polymerization"'
Search Results
2. Construction and performance of PVDF-HFP-matrix comb-like gel copolymer electrolyte for high-performance quasi-solid-state lithium-metal batteries
- Author
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Yi, Lingguang, Chen, Xiaoyi, Zou, Changfei, Liu, Jiali, Cao, Xilin, Tao, Xiyuan, Zang, Zihao, Zheng, Liping, Liu, Li, and Wang, Xianyou
- Published
- 2023
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- View/download PDF
3. Free‐Radical Polymerization Induced Grafting‐to of Polymer Chains onto Aluminum Nanoparticles†.
- Author
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Sun, Panqi, Yang, Chenggong, Peng, Fei, Dang, Junbo, Wang, Wentao, Deng, Daiwu, Zhang, Ning‐Ning, Yang, Yang, and Liu, Kun
- Subjects
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METHYL methacrylate , *GRAFT copolymers , *NANOPARTICLES , *MONOMERS , *POLYMERS - Abstract
Comprehensive Summary: Aluminum nanoparticles (Al NPs) have significant potential applications in various fields due to their unique LSPR. Significant advancements have been achieved in controlling the size and morphology of Al NPs. However, the efficient modification of Al NPs with polymers has not been implemented. Herein, we report a facile and efficient free‐radical polymerization induced grafting‐to (FRPIGt) method for grafting polymer chains onto Al NPs. By optimizing polymerization conditions, we were able to achieve a polymer brush layer with a weight loss fraction of up to 43.3%, which was higher than those of other polymers with carboxyl or primary amine end groups. Moreover, a broad range of vinyl monomers, including styrene, methacrylate, and methyl methacrylate, can be applied using the FRPIGt method to modify Al NPs. In addition, the FRPIGt method can be extended to photoinduced organocatalyzed atom‐transfer‐radical polymerization. This work paves a new path for the preparation of a wide range of polymer‐functionalized Al NPs and their polymer composites to be utilized in various fields. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Free‐Radical Polymerization Induced Grafting‐to of Polymer Chains onto Aluminum Nanoparticles†.
- Author
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Sun, Panqi, Yang, Chenggong, Peng, Fei, Dang, Junbo, Wang, Wentao, Deng, Daiwu, Zhang, Ning‐Ning, Yang, Yang, and Liu, Kun
- Subjects
METHYL methacrylate ,GRAFT copolymers ,NANOPARTICLES ,MONOMERS ,POLYMERS - Abstract
Comprehensive Summary: Aluminum nanoparticles (Al NPs) have significant potential applications in various fields due to their unique LSPR. Significant advancements have been achieved in controlling the size and morphology of Al NPs. However, the efficient modification of Al NPs with polymers has not been implemented. Herein, we report a facile and efficient free‐radical polymerization induced grafting‐to (FRPIGt) method for grafting polymer chains onto Al NPs. By optimizing polymerization conditions, we were able to achieve a polymer brush layer with a weight loss fraction of up to 43.3%, which was higher than those of other polymers with carboxyl or primary amine end groups. Moreover, a broad range of vinyl monomers, including styrene, methacrylate, and methyl methacrylate, can be applied using the FRPIGt method to modify Al NPs. In addition, the FRPIGt method can be extended to photoinduced organocatalyzed atom‐transfer‐radical polymerization. This work paves a new path for the preparation of a wide range of polymer‐functionalized Al NPs and their polymer composites to be utilized in various fields. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Photo-Crosslinked Polyurethane—Containing Gel Polymer Electrolytes via Free-Radical Polymerization Method.
- Author
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Uyumaz, Fatmanur, Yerkinbekova, Yerkezhan, Kalybekkyzy, Sandugash, and Kahraman, Memet Vezir
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POLYMERS , *ENERGY storage , *ELECTROLYTE solutions , *CROSSLINKED polymers , *ADDITION polymerization - Abstract
Using a novel technique, crosslinked gel polymer electrolytes (GPEs) designed for lithium-ion battery applications have been created. To form the photo crosslink via free-radical polymerization, a mixture of polyurethane acrylate (PUA), polyurethane methacrylate (PUMA), vinyl phosphonic acid (VPA), and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) was exposed to ultraviolet (UV) radiation during the fabrication process. The unique crosslinked configuration of the membrane increased its stability and made it suitable for use with liquid electrolytes. The resulting GPE has a much higher ionic conductivity (1.83 × 10−3 S cm−1) than the commercially available Celgrad2500 separator. A crosslinked structure formed by the hydrophilic properties of the PUA-PUMA blend and the higher phosphate content from BMEP reduced the leakage of the electrolyte solution while at the same time providing a greater capacity for liquid retention, significantly improving the mechanical and thermal stability of the membrane. GPP2 shows electrochemical stability up to 3.78 V. The coin cell that was assembled with a LiFePO4 cathode had remarkable cycling characteristics and generated a high reversible capacity of 149 mA h g−1 at 0.1 C. It also managed to maintain a consistent Coulombic efficiency of almost 100%. Furthermore, 91.5% of the original discharge capacity was maintained. However, the improved ionic conductivity, superior electrochemical performance, and high safety of GPEs hold great promise for the development of flexible energy storage systems in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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6. Gas‐free initiation for free‐radical frontal polymerization through charge transfer complexes.
- Author
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Gary, Daniel P., Al Mahmud, Md Abdullah, Dawson, Madison G., and Pojman, John A.
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ELECTRON donor-acceptor complexes ,POLYMERIZATION kinetics ,IODONIUM salts ,PERSULFATES ,ACRYLATES - Abstract
Frontal polymerization is a process in which a localized reaction zone propagates through the coupling of thermal transport and the Arrhenius kinetics of exothermic polymerization. Most initiators that have been used produce volatile by‐products, which create bubbles and voids. Tetraalkyl ammonium persulfates have been used but these require synthesis and do not have long shelf lives. A charge transfer complex (CTC) composed of an iodonium salt, and a phosphine compound has been identified as a gas‐free initiator for free‐radical thermal frontal polymerization. This CTC has 4‐(dimethylamino)phenyldiphenly phophine (DMAPDP) as the donor and p‐(octyloxyphenyl)phenyliodonium hexafluoroantimonate as the acceptor (IOC‐8). The CTC was tested with several acrylates, and all were found to support bubble‐free fronts. We determined the CTC mole ratio for some monomers at which the front velocity reaches a plateau. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Poly(4-vinylbenzyl-g-<bold>β</bold>-butyrolactone) graft copolymer synthesis and characterization using ring-opening polymerization, free-radical polymerization, and “click” chemistry techniques.
- Author
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Savaş, Bedrettin and Öztürk, Temel
- Abstract
The synthesis of poly(4-vinylbenzyl-g-β-butyrolactone) (poly(VB-g-BL)) graft copolymer was carried out by “click” chemistry of terminal azido poly(4-vinylbenzyl chloride) (PVB-N3) and terminal propargyl poly(β-butyrolactone) (β-BL-propargyl). For this purpose, poly(4-vinylbenzyl chloride) (poly-4-VBC) was obtained using 4-vinylbenzyl chloride and 2,2′-azobis(2-methylpropionitrile) by free-radical polymerization. PVB-N3 was synthesized using sodium azide and poly-4-VBC. β-BL-propargyl was obtained by the reaction of β-butyrolactone monomer with propargyl alcohol via ring-opening polymerization. The graft copolymer was also synthesized via “click” chemistry, employing PVB-N3 and β-BL-propargyl. The products were thoroughly characterized by GPC, FT-IR, SEM, and 1H-NMR. DSC and TGA were used to track the graft copolymer’s thermal characteristics. Thermal and spectroscopic measurements verified that the reactions were effectively completed. Poly(4-vinylbenzyl chloride) was obtained by free-radical polymerization. Terminal azido poly(4-vinylbenzyl chloride) was synthesized using sodium azide and poly(4-vinylbenzyl chloride). Terminal propargyl poly(β-butyrolactone) was obtained by β-butyrolactone and propargyl alcohol via ring-opening polymerization. Poly(4-vinylbenzyl-g-β-butyrolactone) graft copolymer was synthesized by “click” chemistry. Thermal and spectroscopic measurements verified that the reactions were completed. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Studies on the Termination Behavior of Styrenic Free‐Radicals.
- Author
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Zhijie, Wei, Pengyu, Yin, Li, Jiang, Qimin, Jiang, Wenyang, Huang, and Bibiao, Jiang
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ADDITION polymerization , *RADICALS (Chemistry) , *FREE radicals , *POLYSTYRENE , *STYRENE , *BENZENE - Abstract
In order to provide more evidence to understand the termination mechanism in styrene free‐radical polymerization, (1‐bromoethyl) benzene and polystyrene with bromide end group (PSt‐Br) synthesized by atom transfer radical polymerization (ATRP) were used as the model compound and model polymer to study the termination behavior of styrenic radical by atom transfer radical coupling (ATRC), and then the NMR chemical shifts of the head‐to‐head enchainment from coupling termination were obtained. SEC and different NMR measurement methods were used to analyze and characterize the products. It is confirmed that there is no bimolecular disproportionation termination between styrenic free radicals, but only coupling termination to form the head‐to‐head enchainment. The proton and carbon chemical shifts of the head‐to‐head enchainment from coupling termination for (1‐bromoethyl) benzene are 2.7–2.86 ppm and ~47.3 ppm. As for the polystyrene through ATRC from PSt‐Br, the corresponding chemical shifts are 2.61–3.29 ppm and ~46.4 ppm, respectively, they are almost the same as the data in our previous paper (~3.05 ppm, ~46.6 ppm) for polystyrene initiated by BPO, proving that the chain termination in free‐radical polymerization of styrene initiated by BPO occurs through primary termination between chain radical and primary radical rather than bimolecular termination between chain radicals. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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9. Molecularly Imprinting Technology and Narrow-Bandgap Semiconductors Application on Photoelectrochemical Sensors Construction
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Gorla, Felipe Augusto, Tarley, César Ricardo Teixeira, Patra, Santanu, editor, and Sillanpaa, Mika, editor
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- 2024
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10. A Comprehensive, Multidimensional First‐Principles Model for Free‐Radical Photopolymerizations in Bulk and Thin Films.
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Dobson, Adam L. and Bowman, Christopher N.
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POLYMERIZATION kinetics , *THIN films , *ATTENUATION of light , *ADDITION polymerization , *DENTAL materials , *POLYMERIZATION - Abstract
Decades of advances in understanding and simulating the polymerization kinetics and structural evolution that arises in free‐radical photopolymerizations of multifunctional monomers are combined into a single, first‐principles 3D model. The model explicitly accounts for polymerization features including diffusion‐controlled kinetics, oxygen inhibition, light attenuation, chain‐length dependent termination, reaction‐diffusion termination, heat transfer, composition and conversion‐dependent material properties, crosslinking effects, and species diffusion. Using the homopolymerization of 1,6‐hexanediol diacrylate as a model system, a minimum of two kinetics experiments performed at different initiation rates are required to fit model parameters. The model accurately predicts known relationships regarding oxygen inhibition, light intensity, and curing temperature for samples of different geometries and boundary conditions. The emphasis of the results herein is placed on the interactions between polymerization features, motivating the importance of a model that accommodates these features all in one simulation. The model is shown to be robust in its handling of thermal boundary conditions, alternative polymerization techniques or mechanisms, and characteristics of 3D voxel formation. The model in this work provides a useful tool for property prediction in a wide variety of applications, most notably coatings, dental materials, industrial photocuring processes, additive manufacturing, and holography, where complex interactions of the various features of polymerization play a substantial role. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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11. Polymerization Behavior and Rheological Properties of a Surfactant-Modified Reactive Hydrophobic Monomer
- Author
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Xin Wen, Lei Wang, Xiaojuan Lai, Guiru Liu, Wenwen Yang, Jinhao Gao, Yameng Liu, and Wenyu Cui
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wormlike micelles ,free-radical polymerization ,synergistic effect ,hydrophobic association ,thixotropy ,viscoelasticity ,Chemistry ,QD1-999 - Abstract
The structures and properties of hydrophobic association polymers can be controlled using micelles. In this work, we synthesize a reactive hydrophobic surfactant monomer, KS-3, from oleic acid, N,N-dimethylpropylenediamine, and allyl chloride. A strong synergistic effect between KS-3 and cocamidopropyl betaine in aqueous solution enhances the hydrophilic dispersibility of KS-3, thereby transforming spherical micelles into cylindrical micelles. KS-3 was grafted onto a polyacrylamide chain via aqueous free-radical polymerization to obtain RES, a hydrophobic association polymer. Structural analysis revealed that the RES polymers assembled in wormlike micelles were more tightly arranged than those assembled in spherical micelles, resulting in a compact network structure in water, smooth surface, and high thermal stability. Rheological tests revealed that the synthesized polymers with wormlike and spherical micelles exhibited shear-thinning properties along with different structural strengths and viscoelasticities. Therefore, controlling the micellar state can effectively regulate the polymer properties. The polymers obtained through wormlike micelle polymerization have potential applications in fields with high demands, such as drug release, water purification, and oilfield development.
- Published
- 2023
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12. The Use of High‐Temperature Semi‐Batch Radical Polymerization to Synthesize Acrylate Based Macromonomers and Structured Copolymers.
- Author
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Bygott, Elizabeth G. and Hutchinson, Robin A.
- Subjects
- *
RADICALS (Chemistry) , *COPOLYMERS , *MACROMONOMERS , *POLYMER fractionation , *POLYMERIZATION , *STERIC hindrance , *BLOCK copolymers , *POLYMERS - Abstract
A high‐temperature starved‐feed semi‐batch operating policy is developed to produce p(acrylates) with high macromonomer content, taking advantage of side reactions inherent to acrylate radical polymerization. This operating strategy results in significantly higher macromonomer content for the polymerization of isobornyl acrylate (iBoA) versus n‐butyl acrylate (BA) under identical operating conditions. This is because steric hindrance favors fragmentation (i.e., terminal double bond (TDB) formation) over addition (i.e., short‐chain or long‐chain branch (LCB) formation), thus increasing the p(iBoA) TDB content and decreasing polymer dispersity. The p(iBoA) macromonomer solution serves as an excellent addition‐fragmentation agent to polymerize a second monomer in a single pot process controlled by sequential feeding, as demonstrates by the production of iBoA‐BA block and comb copolymer structures at different temperatures and macromonomer concentrations. The incorporation of the p(iBoA) macromonomer into a copolymer product is verified by various techniques, including polymer fractionation followed by TDB, composition, and molar mass analyses. Reaction temperature plays a key role in determining whether a blocky versus comb copolymer structure is produced. The ability to synthesize block and comb copolymers by radical polymerization without a mediating agent offers the potential to efficiently produce structured copolymers for industrial applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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13. Polymerization Behavior and Rheological Properties of a Surfactant-Modified Reactive Hydrophobic Monomer.
- Author
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Wen, Xin, Wang, Lei, Lai, Xiaojuan, Liu, Guiru, Yang, Wenwen, Gao, Jinhao, Liu, Yameng, and Cui, Wenyu
- Subjects
POLYMERS ,RHEOLOGY ,MONOMERS ,ADDITION polymerization ,WATER purification ,POLYMER networks ,ALLYL chloride ,BETAINE - Abstract
The structures and properties of hydrophobic association polymers can be controlled using micelles. In this work, we synthesize a reactive hydrophobic surfactant monomer, KS-3, from oleic acid, N,N-dimethylpropylenediamine, and allyl chloride. A strong synergistic effect between KS-3 and cocamidopropyl betaine in aqueous solution enhances the hydrophilic dispersibility of KS-3, thereby transforming spherical micelles into cylindrical micelles. KS-3 was grafted onto a polyacrylamide chain via aqueous free-radical polymerization to obtain RES, a hydrophobic association polymer. Structural analysis revealed that the RES polymers assembled in wormlike micelles were more tightly arranged than those assembled in spherical micelles, resulting in a compact network structure in water, smooth surface, and high thermal stability. Rheological tests revealed that the synthesized polymers with wormlike and spherical micelles exhibited shear-thinning properties along with different structural strengths and viscoelasticities. Therefore, controlling the micellar state can effectively regulate the polymer properties. The polymers obtained through wormlike micelle polymerization have potential applications in fields with high demands, such as drug release, water purification, and oilfield development. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
14. Microemulsion and microsuspension polymerization of methyl methacrylate in surfactant-free microemulsions (SFME).
- Author
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Blahnik, Jonas, Krickl, Sebastian, Schmid, Klaus, Müller, Eva, Lupton, John, and Kunz, Werner
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METHYL methacrylate , *POLYMERS , *MICROEMULSIONS , *ETHANOL , *POLYMERIZATION kinetics , *ADDITION polymerization , *POLYMERIZATION , *GEL permeation chromatography , *MOLAR mass - Abstract
Right side: Schematic drawing of a phase diagram expected for an SFME system and the region, which is suitable for polymerization in SFMEs. Left side: MD simulations of an SFME. Polymerization reactions take place in the oil-rich domains (marked orange). [Display omitted] This article presents a free-radical polymerization method in a mesostructured system – free of any surfactants, protective colloids, or other auxiliary agents. It is applicable for a large variety of industrially relevant vinylic monomers. The aim of this work is to study the impact of surfactant-free mesostructuring on the polymerization kinetics and the polymer derived. So-called surfactant-free microemulsions (SFME) were investigated as reaction media with a simple composition comprising water, a hydrotrope (ethanol, n -propanol, isopropanol, tert -butyl alcohol), and the monomer as the reactive oil phase (methyl methacrylate). Polymerization reactions were performed using oil-soluble, thermal- and UV-active initiators (surfactant-free microsuspension polymerization) and water-soluble, redox-active initiators (surfactant-free microemulsion polymerization). Structural analysis of the SFMEs used and the polymerization kinetics were followed by dynamic light scattering (DLS). Dried polymers were analyzed with regard to their conversion yield by mass balance, the corresponding molar masses were determined using gel permeation chromatography (GPC), and the morphology was investigated by light microscopy. All alcohols are suitable hydrotropes to form SFMEs, except for ethanol, which forms a molecularly disperse system. We observe significant differences in the polymerization kinetics and the molar masses of the polymers obtained. Ethanol leads to significantly higher molar masses. Within a system, higher concentrations of the other alcohols investigated give rise to less pronounced mesostructuring, lower conversions, and lower average molar masses. It could be demonstrated that the effective concentration of alcohol in the oil-rich pseudophases as well as the repulsive effect of the surfactant-free, alcohol-rich interphases constitute the relevant factors influencing polymerization. Concerning the morphology, the polymers derived range from powder-like polymers in the so-called "pre-Ouzo region" over porous-solid polymers in the bicontinuous region to dense, almost compacted, transparent polymers in unstructured regions, comparable to the findings for surfactant-based systems reported in the literature. Polymerizations in SFME comprise a new intermediate between well-known solution (i.e., molecularly dispersed) and microemulsion respectively microsuspension polymerization processes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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15. New Insights on the Kinetics of Persulfate‐Initiated Itaconic Acid Free‐Radical Polymerization.
- Author
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Herrera‐Ordonez, Jorge
- Subjects
- *
ADDITION polymerization , *ITACONIC acid , *POLYMERIZATION kinetics , *ACTIVATION energy , *CHEMICAL decomposition , *POLYMERIZATION - Abstract
A mathematical model is proposed that couples the decomposition kinetics of persulfate (S2O82−) and the free radical polymerization kinetics of itaconic acid (IA); the results are compared with experimental data reported in the literature. It is found that the former is highly affected by the acidification of the aqueous medium which is caused by the equilibrium dissociation of IA but mainly by HSO4− produced by side reactions of the S2O82− decomposition. This qualitatively explains the dependence of d[S2O82−]/dt with [IA] and the initial concentration of persulfate ([S2O82−]0), reported in the literature. According to the model results, temperature overshoots are very likely to occur in the experiments so there is doubt whether the reaction order >1 with respect to [IA] that is sometimes reported in the literature for the rate of polymerization (Rp) is an artifact related to an imprecise temperature (T) control or is due to a more complex mechanism. Due to the higher activation energy of the persulfate decomposition compared to the propagation reaction, small variations of T can lead to significant variations of d[S2O82−]/dt but to an almost imperceptible effect on Rp. Recommendations for future experimental work and refinement of the kinetic model are provided. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
16. Virtual Free-Radical Polymerization of Vinyl Monomers in View of Digital Twins.
- Author
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Sheka, Elena F.
- Subjects
- *
ADDITION polymerization , *DIGITAL twin , *HARTREE-Fock approximation , *ACTIVATION energy , *MONOMERS , *POLYMERS , *POLYMERIZATION - Abstract
The first case of virtual polymerization based on the concept of digital twins (DTs) is presented. The free-radical polymerization of vinyl monomers is considered to be a chain reaction consisting of a set of elementary ones. Those three types, related to the polymerization initiation and propagation as well as to the termination of polymer chain growth, are discussed. Special sets of DTs, whose total number approaches 60, distinguish each reaction type. The calculations are carried out using a semi-empirical version of the unrestricted Hartree–Fock approximation. The main energy and spin-density parameters of the ground state of the DTs are determined. The barrier profiles of two pairs of DTs are calculated, based on which two Evans–Polanyi–Semenov relations, attributed to elementary reactions of type (1) and (2), are constructed. These provide a quite reliable evaluation of the activation energy for the initiation and propagation of the free-radical polymerization of vinyl monomers in all the cases. The decisive role of spins in the formation of the elementary reaction transition states is established. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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17. Facile preparation of polyolefin-based amphiphilic graft copolymer fibers by combination of photo-induced graft copolymerization and electrospinning.
- Author
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ALTINKÖK, Çağatay
- Subjects
- *
GRAFT copolymers , *COPOLYMERIZATION , *FIBERS , *ETHYLENE glycol , *ELECTROSPINNING , *MONOMERS - Abstract
A novel amphiphilic graft copolymer possessing polypropylene (PP) main chain and poly(oligoethylene glycol methacrylate) (POEGMA) pendant units was synthesized starting from chlorinated polypropylene (PP-Cl), and characterized. PP-Cl produced macroradicals at chlorine bounded carbon atoms by visible light irradiation in the presence of dimanganese decacarbonyl [Mn2(CO)10] and initiated the free-radical photopolymerization of an acrylate monomer, namely oligoethylene glycol methacrylate (OEGMA). Furthermore, fiber formation ability of PP-g-POEGMA was tested by electrospinning technique. The chemical structure and some features of the corresponding amphiphilic graft copolymer PP-g-POEGMA was characterized by implementing spectral (FT-IR, ¹H-NMR), chromatographic (GPC), morphological (SEM), water wettability (WCA), and thermal (TGA) analyses. It was clear from the SEM results that the average diameter of the obtained microfibers decreased with the incorporation of POEGMA segments onto the PP-Cl main chain. Based on WCA measurements, PP-g-POEGMA was determined as more wettable than PP-Cl due to its hydrophilic POEGMA building blocks. This facile procedure could be utilized to achieve the amphiphilic commercial polymers for potential bioapplications such as drug delivery. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
18. Experimental study on thermotropic side-chain liquid crystalline photo-sensitive polymers.
- Author
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Jeyasheela, S. and Subramanian, K.
- Subjects
- *
POLYMER liquid crystals , *GLASS transition temperature , *ADDITION polymerization , *IRRADIATION , *MICROSCOPY , *BENZOYL peroxide - Abstract
When the chalcone moiety and methylene spacers are bonded to polymer backbone, they are expected to incorporate photosensitive and liquid crystalline properties, respectively. The thermotropic side-chain liquid crystalline photosensitive polymers were synthesized using 4-phenyl styryl carbonyl (phenyl-4-oxy-4-hexyl) methacrylate (PSCPOHMA) and 4-phenyl styryl carbonyl (phenyl-4-oxy-4-decyl) methacrylate (PSCPODMA) monomers by free-radical polymerization using benzoyl peroxide (BPO) as an initiator. The structures of the synthesized monomers and polymers were confirmed by FT-IR, 1H NMR and 13C NMR techniques. The thermal stability and glass transition temperature of the poly (PSCPOHMA) were higher than that of the poly (PSCPODMA). The photocrosslinking of the polymers on irradiation with UV light established that the polymers followed 2π + 2π cyclo addition. The rate of crosslinking increased with increase in the length of the methylene chain. The mesophase of the polymers was also characterized using x-ray diffraction analysis. The liquid crystalline behavior of the polymers was confirmed by DSC and Hot stage optical polarized microscopy (HOPM).The polymers exhibited nematic phase in HOPM. So the polymers have high potential for application in photo resists and electro optic technology. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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19. A green approach to synthesize silver nanoparticles in gelatin/poly(2-hydroxyethylmethacrylate-co-2-acrylamido-2-methyl-1-propanesulfonic acid) hydrogels with Verbascum Longipedicellatum extract and their antibacterial activity.
- Author
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Kıvanç, Mehmet Rıza
- Subjects
- *
SILVER ions , *SILVER nanoparticles , *GELATIN , *ANTIBACTERIAL agents , *FOURIER transform infrared spectroscopy , *ESCHERICHIA coli , *HYDROGELS , *SCANNING electron microscopy - Abstract
This study aimed to explain the production and the characterization of gelatin/poly(2-hydroxyethylmethacrylate-co-2-Acrylamido-2-methyl-1-propanesulfonic acid), Gel/p(HEMA-co-AMPS), hydrogels including silver nanoparticles (AgNP) that were developed with a simple, cost-effective and environmentally-friendly process. Silver ions were added to the Gel/p(HEMA-co-AMPS) hydrogel matrix synthesized via free radical polymerization, and silver nanoparticles were developed by in-situ reduction of silver ions (Ag+) in the swollen hydrogel using Verbascum Longipedicellatum plant extract. The structure and morphology of the prepared nanocomposite hydrogel were confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy-energy-dispersive X-ray spectroscopy (TEM-EDX), X-ray diffraction analysis (XRD) and thermogravimetric analysis (TGA). In addition, the swelling properties of hydrogels were investigated and AgNPs embedded in the hydrogel network were found to absorb more water, improving the swelling properties of hydrogels. Finally, the antibacterial activity of silver nanocomposites against S. aureus, E. faecalis, B. Subtilis, B. cereus, E. coli, P. aeruginosa as bacterial agents and C. albicans as fungal agent was examined. Therefore, the present study offers a multi-component hydrogel containing AgNPs with low-cost and environmentally-friendly fabrication process for application as bactericidal materials in biotechnology and biomedical fields. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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20. [Preparation and methodological analysis of chitosan-based ultrasound-coupled hydrogel pads].
- Author
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Chen D, Yuan J, Deng X, Ding L, An Z, and Luo W
- Subjects
- Ultrasonography, Polymerization, Sulfonic Acids chemistry, Alkanesulfonates chemistry, Tensile Strength, Freeze Drying, Temperature, Chitosan chemistry, Hydrogels chemistry, Acrylamides chemistry
- Abstract
This study aims to optimize the process for preparing chitosan-based ultrasound-coupled hydrogel pads and investigate their application potential in ultrasonography. Chitosan, 2-acrylamido-2-methylpropanesulfonic acid, and N-isopropylacrylamide were used as the main materials to prepare chitosan-based ultrasound-coupled hydrogel pads. The free-radical polymerization conditions were optimized by a three-factor, three-level orthogonal test with the tensile strength and ultrasound image quality of the hydrogel pads as evaluation indicators. The optimal prescription was selected by optimizing three factors of raw material ratio, polymerization temperature, and freeze-drying time. The structure and performance of the hydrogel pads were characterized by a scanning electron microscope, a universal testing machine, and an ultrasonic diagnostic instrument. The results showed that the optimal prescription was as follows: the chitosan: 2-acrylamide-2-methylpropanesulfonic acid: N-isopropylacrylamide ratio of 2:0.55:17.27, the polymerization temperature of 25 ℃, and the freeze-drying time of 48 h. The ultrasonically-coupled hydrogel pads prepared under these conditions were transparent, with a porous structure, good adhesion, and high tensile strength. The hydrogel pads had good swelling properties and the swelling degree decreased slowly on day 10. The quality of the ultrasound images obtained via chitosan-based hydrogel pads was not significantly different from that obtained via medical ultrasound coupling agent. In this study, we analyzed the effects of different preparation processes on the gel formation of chitosan-based ultrasound-coupled hydrogel pads. The hydrogel pads were transparent and mild and non-irritating to the human body, serving as an ultrasound transmission material for ultrasonography.
- Published
- 2024
- Full Text
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21. Synthesis and Characterization of Chitosan-Acrylic Acid Based Hydrogels and Investigation the Properties of Bilayered Design with Incorporated Alginate Beads.
- Author
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Erceg, Tamara, Brakus, Gaja, Stupar, Alena, Cvetinov, Miroslav, Hadnađev, Miroslav, and Ristić, Ivan
- Subjects
HYDROGELS ,ALGINATES ,ALGINIC acid ,ADDITION polymerization ,MODULUS of rigidity ,ELASTIC modulus - Abstract
The paper presents the synthesis of hydrogels via free-radical polymerization, based on Chitosan (CS) grafted with Acrylic acid (AA), using a two-step procedure. Free-radical polymerization has given strong hydrogels with compact structure, dominant elastic behavior, and long linear viscoelastic region. The results of rheological studies have shown that obtained hydrogels have significantly improved mechanical properties in comparison to chitosan hydrogels obtained by other sustainable methods. A step forward in the investigation of the potential application of chitosan hydrogels in wound dressing systems has been made by preparation of the bilayer design by embedding a layer of active compound-loaded alginate beads into the contact surface between two conjoined units of CS/AA hydrogels. Wild garlic (Allium ursinum L.) dried extract was used as an active compound because of its antimicrobial activity and green properties. This system has demonstrated pH-dependent release of extract and higher shear elastic modulus values than ordinary disc gels. A conducted study has given preliminary results for the possible application of bilayer chitosan-based hydrogels in wound dressing systems and represents the first step towards extrapolating the proposed design across other application fields. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
22. Entrapment of glucose oxidase from Aspergillus niger ISL-09 in poly(acrylamide-co-acrylic acid) hydrogels for improved stability and catalytic efficiency towards industrial applications.
- Author
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Rukhma, Ali, Sikander, Jahangeer, Muhammad, Rehman, Muti Ur, Liyaqat, Iqra, and Qamar, Sarmad Ahmad
- Subjects
GLUCOSE oxidase ,ADDITION polymerization ,ASPERGILLUS niger ,SOYBEAN meal ,FUNGAL spores - Abstract
The present study highlights the true potential of Aspergillus niger ISL-09 to produce glucose oxidase (GOx) and focuses on improving the catalytic properties of GOx by entrapping it in poly acrylamide-co-acrylic acid (AAm-co-AAc) hydrogels, fabricated by free-radical polymerization method. For this purpose, the optimum conditions for GOx activity were found to be: 15 g soybean meal (SBM) substrate, 20 mL moisture content, 96 h incubation period, and 1.5 mL of fungal spore suspension. The purified extracellular GOx was observed to have 32.4% yield, with 0.02 U/mg specific activity and approximately 80 kDa subunit molecular weight. The GOx was most active at pH 5.5 and 40 °C. The immobilization of GOx in poly (AAm-co-AAc) hydrogels led towards improved stability and catalytic efficiency, resulting in a 21.7% increase in activity compared to free enzyme. The study also examined the potential of GOx in the pharmaceutical and textile industries as Ca-gluconate producer and bleaching agent, respectively. The study concludes that A. niger ISL-09 is a promising source for GOx production under optimal conditions. Furthermore, the immobilization of GOx in poly (AAm-co-AAc) hydrogels can significantly improve its catalytic properties, making it suitable for different industrial applications. However, further scaling up is required for the better implementation in industry. • Glucose oxidase (GOx) from A. niger ISL-09 was immobilized in poly(acrylamide-co-acrylic acid) hydrogels. • Significantly improved GOx stability and catalytic efficiency was observed after immobilization. • The potential of GOx was determined as Ca-gluconate producer and bleaching agent for pharma and textile industries, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
23. New glyco-copolymers containing α-D-glucofuranose and α-D-mannofuranose groups synthesized by free-radical polymerization of sugar-based monomers.
- Author
-
Namazi, Hassan, Pooresmaeil, Malihe, and Oskooie, Maryam Nasiri
- Subjects
- *
ADDITION polymerization , *PROTON magnetic resonance , *MONOMERS , *NUCLEAR magnetic resonance , *RANDOM copolymers , *COPOLYMERIZATION - Abstract
Carbohydrates are safe materials with the potential of application in various areas, hence, in recent years, a growing interest has been attracted to the synthesis of the new systems containing carbohydrates. By considering this and based on the carbohydrate's merits, in this work, the new two different random glyco-copolymers were prepared through the polymerization of the α-D-glucofuranose- and α-D-mannofuranose-based monomers. A facile free-radical polymerization technique was utilized for glyco-copolymers synthesis in the presence of benzoyl peroxide (BPO) as an initiator. Fourier transform infrared (FT-IR) technique was used for investigating the achievements in the synthesis of copolymers. In the proton nuclear magnetic resonance (1H NMR) spectroscopy analysis, the absence of any peaks in the rigon related to vinylic protons confirmed the successful synthesizing of glyco-copolymers. As well as, enhancing the intensity of the peaks in the 0.60–2.39 ppm which is related to the formed aliphatic protons as a result of vinylic glycomonomers copolymerization is the strong witness for success in copolymerization. In this way and by considering the special structure of the prepared glyco-copolymers and based on the review of the published literature, it is expected that the prepared new glyco-copolymers be a good candidate for biomedicinal applications. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
24. Electron Paramagnetic Resonance Spin Trapping (EPR–ST) Technique in Photopolymerization Processes.
- Author
-
Peyrot, Fabienne, Lajnef, Sonia, and Versace, Davy-Louis
- Subjects
- *
ELECTRON paramagnetic resonance , *PHOTOPOLYMERIZATION , *ELECTRON paramagnetic resonance spectroscopy , *ADDITION polymerization - Abstract
To face economic issues of the last ten years, free-radical photopolymerization (FRP) has known an impressive enlightenment. Multiple performing photoinitiating systems have been designed to perform photopolymerizations in the visible or near infrared (NIR) range. To fully understand the photochemical mechanisms involved upon light activation and characterize the nature of radicals implied in FRP, electron paramagnetic resonance coupled to the spin trapping (EPR–ST) method represents one of the most valuable techniques. In this context, the principle of EPR–ST and its uses in free-radical photopolymerization are entirely described. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
25. Modification of Poly(Styrene‐co‐Acrylonitrile) with Tetrazine by Inverse Electron Demand Diels‐Alder Reaction.
- Author
-
Meyvacı, Ergül and Öztürk, Temel
- Subjects
- *
DIELS-Alder reaction , *TETRAZINE , *PROTON magnetic resonance , *GEL permeation chromatography , *ADDITION polymerization - Abstract
Poly(styrene‐co‐acrylonitrile) [P(SAN)] copolymer was obtained by using styrene and acrylonitrile monomers via free‐radical polymerization. The tetrazine groups were formed in the P(SAN) copolymer backbone by using 2‐fluorobenzyl cyanide, hydrazine hydrate, zinc iodide as the catalyst, and sodium nitrile. The tetrazine groups in the copolymer backbone were modified using trans‐cyclooctenol by the Inverse Electron Demand Diels‐Alder reaction. The spectroscopic properties of the obtained products were determined by Fourier transform infrared and proton nuclear magnetic resonance and their thermal properties were determined by thermogravimetric analysis and differential scanning calorimetry techniques. The average molecular weights of the synthesized polymers were defined by using gel permeation chromatography method. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
26. Photoinduced Controlled/Living Polymerizations.
- Author
-
Aydogan, Cansu, Yilmaz, Gorkem, Shegiwal, Ataulla, Haddleton, David M., and Yagci, Yusuf
- Subjects
- *
LIVING polymerization , *ADDITION polymerization , *POLYMERIZATION , *THERMOCHEMISTRY , *PHOTOCHEMISTRY - Abstract
The application of photochemistry in polymer synthesis is of interest due to the unique possibilities offered compared to thermochemistry, including topological and temporal control, rapid polymerization, sustainable low‐energy processes, and environmentally benign features leading to established and emerging applications in adhesives, coatings, adaptive manufacturing, etc. In particular, the utilization of photochemistry in controlled/living polymerizations often offers the capability for precise control over the macromolecular structure and chain length in addition to the associated advantages of photochemistry. Herein, the latest developments in photocontrolled living radical and cationic polymerizations and their combinations for application in polymer syntheses are discussed. This Review summarizes and highlights recent studies in the emerging area of photoinduced controlled/living polymerizations. A discussion of mechanistic details highlights differences as well as parallels between different systems for different polymerization methods and monomer applicability. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
27. Charge transfer complexes as dual thermal/photo initiators for free‐radical frontal polymerization.
- Author
-
Gary, Daniel P., Ngo, Douglas, Bui, Amber, and Pojman, John A.
- Subjects
ELECTRON donor-acceptor complexes ,ADDITION polymerization ,POLYMERIZATION ,IODONIUM salts ,AROMATIC amines ,ELECTRON donors - Abstract
Frontal polymerization is a process in which a localized reaction zone propagates from the coupling of thermal transport and the Arrhenius rate dependence of an exothermic polymerization; monomer is converted into polymer as the front passes through an unstirred medium. Herein we report the first study of charge transfer complexes (CTCs) as photo/thermal initiators for free‐radical frontal polymerization. Front velocity was studied as a function of mole ratio between an aromatic amine, such as dimethyl‐p‐toluidine or dimethylaniline, and an iodonium salt. It was found that the front velocity reached a maximum at a certain mole ratio of amine to iodonium salt. The velocity remained constant upon increasing the ratio of amine to iodonium salt past this critical ratio. Fronts were also studied using N‐phenyl glycine as an electron donor, but its utility was limited by low solubility. Lastly, the steric and electronic effects of the iodonium salt and counter anion were explored. It was found that CTCs using iodonium salts with less nucleophilic anions gave higher front velocities. In terms of intrinsic reactivity, the CTC composed of N,N‐dimethyl‐p‐toluidine and bis[4‐(tert‐butyl)phenyl]iodonium tetra(nonafluoro‐tert‐butoxy)aluminate gave the highest front velocity per molal of iodonium salt. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
28. Preparation and characterization of maleic anhydride‐grafted desulfurization rubber powder by free‐radical polymerization.
- Author
-
Kong, Peipei, Chen, Xianhua, Xu, Gang, and Wei, Wei
- Subjects
RUBBER powders ,ADDITION polymerization ,COMPATIBILIZERS ,RUBBER ,FOURIER transform infrared spectroscopy ,ELEMENTAL analysis ,X-ray photoelectron spectroscopy - Abstract
The objective of the article was to enhance the recycling value of solid waste rubber by surface functionalization of desulfurized rubber powder using a one‐pot method based on free‐radical polymerization theory. Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy, and elemental analysis were used to characterize the maleic anhydride‐grafted desulfurized rubber powder, and the grafting mechanism was also investigated. Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy confirmed that maleic anhydride was grafted onto the desulfurized rubber powder. Thermogravimetric analysis indicated that the maleic anhydride‐grafted desulfurized rubber powder and desulfurized rubber powder possessed different thermal properties and structure. The results of scanning electron microscopy and elemental analysis illustrated that the surface of the desulfurized rubber powder was covered with a layer of fold‐like maleic anhydride polymer. The mechanism of grafting desulfurized rubber powder with maleic anhydride may be achieved by replacing the active α‐H on the methylene group of the desulfurized rubber macromolecule chain. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
29. Controlling the Friction of Gels by Regulating Interfacial Oxygen During Polymerization.
- Author
-
Simič, Rok and Spencer, Nicholas D.
- Abstract
Hydrogel surfaces are of great interest in applications ranging from cell scaffolds and transdermal drug-delivery patches to catheter coatings and contact lenses. In this work, we propose a method to control the surface structure of hydrogels, thereby tailoring their frictional properties. The method is based on oxygen inhibition of the free-radical polymerization reaction during synthesis and enables (i) control of friction over more than an order in magnitude and (ii) spatial control of friction as either a continuous gradient or a distinct pattern. The presented method has successfully been applied to acrylamide-, diacrylate- and methacrylate-based gels, illustrating the universality of the presented method, and its potential use in the above-mentioned applications. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
30. Facile tuning of hydrogel properties by manipulating cationic-aromatic monomer sequences.
- Author
-
Fan, Hailong, Cai, Yirong, and Gong, Jian Ping
- Abstract
Copolymer hydrogels formed from cationic and aromatic monomers with identical monomer compositions but different average sequences were synthesized by free-radical copolymerization in various solvents. We found that hydrogels with one-component-rich segments are mechanically stronger than those with adjacent-rich monomer sequences in water, while hydrogels with a rich cation-π adjacent sequence showed excellent mechanical strength and underwater adhesion in saltwater (0.7 M NaCl). The molecular mechanisms for these behaviors are discussed in terms of polymer structures. This work reveals the importance of monomeric sequences in determining hydrogel properties and provides a facile approach to develop hydrogels with different properties but the same monomer composition. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
31. FTIR and NMR characterization of thermosetting methyl methacrylate terminated poly(2,6-dimethyl-1,4-phenylene oxide)—triallyl isocyanurate copolymer.
- Author
-
Yu, Xueyi, Fang, Zeming, Qin, Yijing, Lu, Dong, Liu, Qianfa, Luo, Li, Lin, Zhiyong, and Wang, Ke
- Abstract
Thermosetting Polyphenylene oxide (PPO)/Triallyl isocyanurate (TAIC) based composite systems have attracted considerable attentions in recent years due to their excellent performance as the substrate for printed circuit boards (PCBs) used for 5G networks. Since the residuals of -OH and -C = C- groups have significant effects on the properties of the substrate, especially the dielectric properties and thermal stability, it is critical to establish valid methods for characterizing these systems. In this work, FTIR, 1H-NMR and 13C-SSNMR were employed to qualitatively and quantitatively characterize the -OH and -C = C- groups in the methyl methacrylate (MMA) terminated PPO/TAIC co-cured system. No -OH groups were detected on the molecular chains of PPO oligomers, indicating that almost all the phenolic hydroxyl groups in the precursor had been substituted. During the curing, no new -OH groups were generated but some -C = C- groups were left unreacted. FTIR quantitative analysis showed that these -C = C- groups belonged to TAIC and the residual ratio of -C = C- could be as high as 60.37%. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
32. Chapter Seven - From batch to continuous free-radical polymerization: Recent advances and hurdles along the industrial transfer.
- Author
-
Ilare, Juri and Sponchioni, Mattia
- Abstract
The care of safety and environment is nowadays an essential aspect in the conduction of every kind of factory. A decisive contribution to these aspects is given by the conversion from batch to continuous processes. In polymer manufacturing, this transition allows to better manage important safety and pollution concerns, such as energy transport phenomena and process emissions. This, in turn, facilitates the fulfilling of the more and more stringent requirements imposed by local and international regulatory agencies. In addition, through this process intensification, it is also possible to optimize both investment and operative costs, thus overcoming the current profit margin reduction in the field of polymerizations. The aim of this chapter is to provide an insight into the technical and process difficulties that are currently hampering the transition from batch to continuous free-radical polymerization (FRP). The discussion is driven by considering key points in polymer manufacturing, including safety, environmental concerns, product quality and cost management. For a seek of clarity, we drove the discussion by considering the two main modalities in which the FRP can be conducted, namely homogenous and heterogeneous reactions. Extensive reference to literature examples is made to highlight the state of art in the field and the recent innovations toward continuous processes. Finally, successful examples of such auspicable transition achieved on an industrial scale are presented, trying to highlight the features that can be generalized to reach the goal. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
33. Free-Radical Polymerization of Styrene: Kinetic Study in a Spinning Disc Reactor (SDR)
- Author
-
Marija Vicevic, Katarina Novakovic, and Kamelia Boodhoo
- Subjects
kinetics ,styrene ,poly(styrene) ,free-radical polymerization ,spinning disc reactor ,process intensification ,Technology ,Chemical technology ,TP1-1185 - Abstract
Free-radical polymerization of styrene conducted in a spinning disc reactor (SDR) results in significant increases in conversion in one disc pass, equivalent to a few seconds of residence time, with little change in the number average and weight average molecular weights and polydispersity compared to a SDR feed pre-polymerized in a batch reactor. Results of our experimental studies are presented in this paper and a rationale, based on simulation studies, is offered to explain these observations. It is shown that phenomena such as large increases in conversion that do not impact on molecular weights and molecular weight distribution is a result of a simultaneous increase in both the initiator decomposition rate and the propagation rate. The increases in these rate constants, predicted by our modeling studies, provide the driving forces that characterize a polymerization process in a SDR reactor, with the centrifugal force having different degrees of influence on individual reaction steps. This is attributed to different molecular sizes being involved in each of the polymerization reaction steps. The highest impact is observed on the initiator decomposition rate constant, as this reaction step involves a small molecule. Lesser impact is observed on the propagation rate constant, as this reaction step involves interaction of one small molecule and one large reactive species, whilst no or very small effect is seen in the case of the termination rate constant as large reactive species are involved. Developed constant variance model was used to estimate reaction parameters at different temperatures (i.e., initiator efficiency f, rate constants kd, kp, and kt) from the acquired experimental data in order to estimate activation energy (Ea) and pre-exponential factor (A) in a SDR. Data analysis at various SDR operating temperatures suggested activation energy for the styrene polymerization in the SDR as 40.59 ± 1.11 kJ mol−1.
- Published
- 2021
- Full Text
- View/download PDF
34. Synthesis and characterization of poly(methyl methacrylate-g-α-methyl-β-alanine) copolymer using "Grafting Through" method.
- Author
-
Savaş, Bedrettin, Çatıker, Efkan, Öztürk, Temel, and Meyvacı, Ergül
- Subjects
- *
ADDITION polymerization , *COPOLYMERS , *MACROMONOMERS , *LIGHT scattering , *COPOLYMERIZATION , *METHACRYLATES , *THERMAL analysis , *POLYMERIZATION - Abstract
Synthesis of poly(methyl methacrylate-g-α-methyl-β-alanine) [poly(MMA-g-mBA)] copolymer was achieved through base-catalyzed hydrogen transfer polymerization (HTP) and free-radical polymerization (FRP), respectively. For this purpose, poly(α-methyl β-alanine) [PmBA] oligomer with olefinic end-group as a macromonomer was synthesized from methacrylamide by base-catalyzed HTP method. Poly(MMA-g-mBA) in different compositions was obtained through FRP of methyl methacrylate/the PmBA macromonomer mixtures using the "grafting through" method. The characterization of the copolymerization products was accomplished by using multi-instruments such as 1H-NMR, FTIR, TGA, and dynamic light scattering. The spectroscopic and thermal analysis of the graft copolymer reveal that the copolymer was easily built through a combination of HTP and FRP techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
35. Kinetics of free radical polymerization of methyl methacrylate initiated by pentazadienes.
- Author
-
Vyshnevskyi, Dmitry and Kolendo, Aleksey
- Subjects
- *
POLYMERIZATION , *METHYL methacrylate , *METHYL radicals , *FREE radicals , *FREE radical reactions , *ADDITION polymerization - Abstract
The free radical polymerization reaction of methyl methacrylate initiated by the new initiators, bis- and mono-pentazadienes, has been studied. It was found, that the polymerization rate increases with an increase of the donor character of a substituent in aryl moiety. The direct correlation between the number of azo groups in a molecule and a polymerization rate was not observed. The high value of the reaction orders by the initiator indicates the occurrence of side processes. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
36. Synthesis and identification of polystyrene via conventional and controlled radical polymerization methods: Effect of temperature, initiator and transfer agent on molecular weight and reaction rate
- Author
-
Mojtaba Farrokhi and Mahdi Abdollahi
- Subjects
Polystyrene ,low to high molecular weights ,thermal polymerization (TP) ,free-radical polymerization ,(reverse) iodine transfer radical polymerization ((R)ITP) ,Polymers and polymer manufacture ,TP1080-1185 - Abstract
Polystyrene (PSt) has been known as one of the important polymers with a wide range of applications. Ability to synthesize PSt with different but predictable molecular weights for various applications is very important in the laboratories and industries. In this study, using various simple and inexpensive techniques with only free radical mechanism, it was tried to synthesize PSt with different low (< 2×104 g mol-1) to high (> 105 g mol-1) molecular weights. PSts with high and moderate molecular weights (2×104-105 g mol-1) were synthesized using thermal and conventional free radical polymerizations, respectively. Reverse iodine transfer radical polymerization (RITP) was utilized to synthesize PSt with a low and controlled molecular weight. Conversion, molecular weight distribution and PSt structure were analyzed using 1H-NMR spectroscopy and size exclusion chromatography (SEC), respectively. Moreover, ω-iodo poly(dimethylsiloxane), i.e. PDMS-I, was also used as a macrotransfer agent for ITP of styrene. Diblock copolymer of PDMS-b-PSt was characterized by 1H-NMR and SEC analyses.
- Published
- 2019
- Full Text
- View/download PDF
37. Ghost‐Mirror Approach for Accurate and Efficient Kinetic Monte Carlo Simulation of Seeded Emulsion Polymerization.
- Author
-
Tripathi, Amit K. and Tsavalas, John G.
- Subjects
- *
EMULSION polymerization , *MAGNITUDE (Mathematics) , *MONTE Carlo method , *ADDITION polymerization - Abstract
The kinetic Monte Carlo (kMC) method is well suited to the simulation of seeded emulsion polymerization reactions. Inadequate simulation volume results in an incorrect radical entry rate, and as such that inaccuracy propagates into the particle phase simulation. A novel kMC method is described here that has coined the Ghost‐Mirror approach (GM‐kMC) to guarantee sufficient aqueous phase simulation volume while minimizing the number of dispersed phase environments, and while maintaining accuracy and consistency with results produced by kMC simulations. To do so, a subset of a kMC method is replicated where only the aqueous phase reactions are treated in that extended volume; particle phases in those replicated volumes are untreated, as "ghosts". In doing so, a critical condition for aqueous phase simulation volume is calculated to yield accurate results in the overall system. Important to emphasize though is that one does not require the equivalent number of simulated particles in the GM‐kMC approaches. The required number of particles to simulate accurate results can be even orders of magnitude smaller than the kMC approach; inherently offering significant gains in computational efficiency. This is extended further, reducing the required simulation time, by a hybrid extension to this GM‐kMC method. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
38. A cholecystic extracellular matrix‐based hybrid hydrogel for skeletal muscle tissue engineering.
- Author
-
Raj, Reshmi, Sobhan, Praveen K., Pratheesh, Kanakarajan V., and Anilkumar, Thapasimuthu V.
- Abstract
Tailoring the properties of extracellular matrix (ECM) based hydrogels by conjugating with synthetic polymers is an emerging method for designing hybridhydrogels for a wide range of tissue engineering applications. In this study, poly(ethylene glycol) diacrylate (PEGDA), a synthetic polymer at variable concentrations (ranging from 0.2 to 2% wt/vol) was conjugated with porcine cholecyst derived ECM (C‐ECM) (1% wt/vol) and prepared a biosynthetic hydrogel having enhanced physico‐mechanical properties, as required for skeletal muscle tissue engineering. The C‐ECM was functionalized with acrylate groups using activated N‐hydroxysuccinimide ester‐based chemistry and then conjugated with PEGDA via free‐radical polymerization in presence of ammonium persulfate and ascorbic acid. The physicochemical characteristics of the hydrogels were evaluated by Fourier transform infrared spectroscopy and environmental scanning electron microscopy. Further, the hydrogel properties were studied by evaluating rheology, swelling, gelation time, percentage gel fraction, in vitro degradation, and mechanical strength. Biocompatibility of the gel formulations were assessed using the C2C12 skeletal myoblast cells. The hydrogel formulations containing 0.2 and 0.5% wt/vol of PEGDA were non‐cytotoxic and found suitable for growth and proliferation of skeletal myoblasts. The study demonstrated a method for modulating the properties of ECM hydrogels through conjugation with bio‐inert polymers for skeletal muscle tissue engineering applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
39. Chapter Seven - From batch to continuous free-radical polymerization: Recent advances and hurdles along the industrial transfer.
- Author
-
Ilare, Juri and Sponchioni, Mattia
- Abstract
The care of safety and environment is nowadays an essential aspect in the conduction of every kind of factory. A decisive contribution to these aspects is given by the conversion from batch to continuous processes. In polymer manufacturing, this transition allows to better manage important safety and pollution concerns, such as energy transport phenomena and process emissions. This, in turn, facilitates the fulfilling of the more and more stringent requirements imposed by local and international regulatory agencies. In addition, through this process intensification, it is also possible to optimize both investment and operative costs, thus overcoming the current profit margin reduction in the field of polymerizations. The aim of this chapter is to provide an insight into the technical and process difficulties that are currently hampering the transition from batch to continuous free-radical polymerization (FRP). The discussion is driven by considering key points in polymer manufacturing, including safety, environmental concerns, product quality and cost management. For a seek of clarity, we drove the discussion by considering the two main modalities in which the FRP can be conducted, namely homogenous and heterogeneous reactions. Extensive reference to literature examples is made to highlight the state of art in the field and the recent innovations toward continuous processes. Finally, successful examples of such auspicable transition achieved on an industrial scale are presented, trying to highlight the features that can be generalized to reach the goal. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
40. Cell encapsulation spatially alters crosslink density of poly(ethylene glycol) hydrogels formed from free-radical polymerizations.
- Author
-
Chu, Stanley, Maples, Mollie M., and Bryant, Stephanie J.
- Subjects
ADDITION polymerization ,ETHYLENE glycol ,CARTILAGE cells ,HYDROGELS ,TISSUE engineering ,DENSITY - Abstract
Photopolymerizable poly(ethylene glycol) (PEG) hydrogels are a promising platform for chondrocyte encapsulation and cartilage tissue engineering. This study demonstrates that during the process of encapsulation, chondrocytes alter the formation of PEG hydrogels leading to a reduction in the bulk and local hydrogel crosslink density. Freshly isolated chondrocytes were shown to interact with hydrogel precursors, in part through thiol-mediated events between dithiol crosslinkers and cell surface free thiols, depleting crosslinker concentration and causing a reduction in the bulk hydrogel crosslink density. This effect was more pronounced with increasing cell density at the time of encapsulation. Encapsulation of chondrocytes in fluorescently labeled hydrogels exhibited a gradient in hydrogel density around the cell, which was abrogated by treatment of the cells with the antioxidant estradiol prior to encapsulation. This gradient led to spatial variations in the degradation behavior of a hydrolytically degradable PEG hydrogel, creating regions devoid of hydrogel surrounding cells. Collectively, findings from this study indicate that the antioxidant defense mechanisms in chondrocytes alter the resultant properties of PEG hydrogels formed by free-radical polymerizations. These interactions will have a significant impact on tissue engineering, affecting the local microenvironment around cells and how tissue grows within the hydrogels. Cell encapsulations in synthetic hydrogels formed by free-radical polymerizations offer numerous benefits for tissue engineering. Herein, we studied cartilage cells and identified that during encapsulation, cells interfered with hydrogel formation through two distinct mechanisms. Thiol-mediated events between monomers led to monomer depletion and a lower crosslinked hydrogel. Cells' antioxidant defense mechanisms interfered with free-radicals and inhibited hydrogel formation near the cell. These cell-mediated effects led to softer hydrogels and created unique hydrogel degradations patterns causing rapid degradation around the cells. The latter has benefits for tissue engineering, where these regions provide space for tissue growth. Overall, this study demonstrates that cells play a key role in how the hydrogel structure forms when cells are present. Image, graphical abstract [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
41. Kinetic Studies of Photopolymerization of Monomer‐Containing Deep Eutectic Solvents.
- Author
-
Fazende, Kylee F., Gary, Daniel P., Mota‐Morales, Josué D., and Pojman, John A.
- Subjects
- *
METHYL methacrylate , *PHOTOPOLYMERIZATION , *ACRYLIC acid , *METHACRYLIC acid , *SOLVENTS , *EUTECTICS , *EUTECTIC reactions - Abstract
The kinetics of photopolymerization in deep eutectic solvents (DESs) is investigated through real‐time Fourier transform‐infrared spectrometry (RT‐FTIR). The systems of this study are choline chloride (ChCl) DESs made of acrylic acid and methacrylic acid (DES monomers) and a nonreactive analog isobutyric acid (IBA). The DES consisting of the analog also contains the monomer methyl methacrylate (MMA). Analysis of the evolution of conversion indicates dramatic increase in polymerization rate when comparing the polymerization of the DES monomers to pure monomer polymerization. A significant increase in polymerization rate is also seen in the systems that include a methyl ester derivative of the hydrogen bond donor monomer (e.g., MMA) in a nonpolymerizable DES (e.g., IBA−ChCl). It is proposed that the increased solvent viscosity, preorganization due to hydrogen bonding, and the polarity of the DES around the monomers play a role in the enhancement of the polymerization rate. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
42. Enzyme induced molecularly imprinted polymer on SERS substrate for ultrasensitive detection of patulin.
- Author
-
Zhu, Yuanyuan, Wu, Long, Yan, Heng, Lu, Zhicheng, Yin, Wenmin, and Han, Heyou
- Subjects
- *
SERS spectroscopy , *IMPRINTED polymers , *MOLECULAR imprinting , *UNIFORM spaces , *DETECTION limit , *ENZYMES , *SURFACE enhanced Raman effect - Abstract
We designed a new type of MIP-SERS substrate for specific and label-free detection of patulin (PAT), by combining molecular imprinting polymer (MIP) selectivity and SERS technology sensitivity. Initially, the solid substrate of PDMS/AAO was prepared using poly dimethylsiloxane (PDMS) concreted anodized aluminum oxide (AAO) template. Then moderate Au was sputtered on the surface of PDMS/AAO to obtain Au/PDMS/AAO SERS substrate. Based on the HRP enzyme initiated in situ polymerization on the Au/PDMS/AAO, the MIP-SERS substrate was successfully synthesized with selective polymer and high tense of SERS "hot spots". The new MIP-SERS substrate showed strong SERS enhancement effect and good selectivity for PAT. Besides, the results showed that the method owned a linear range from 5 × 10−10 to 10−6 M with the limit of detection (LOD) of 8.5 × 10−11 M (S/N = 3) for PAT. The proposed method also exhibited acceptable reproducibility (relative standard deviation, RSD = 4.7%),good stability (Raman intensity is above 80% after two weeks) and recoveries from 96.43% to 112.83% with the average RSD of 6.3%. The substrate is easy to use without complex sample pretreatment, which makes it a potential candidate as a rapid and sensitive detection method in food samples. Image 1 • A new type of MIP-SERS substrate which combined the selectivity of molecular imprinting polymer (MIP) and the sensitivity of SERS technology was prepared with uniform structure and dense "hot spots". • The method behaved a wide linear range of 5×10 ‒10 to 10 ‒6 M with limit of detection of 8.5×10 ‒11 M. • The MIP-SERS substrate can be easily used without complex sample pretreatment. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
43. Synthesis and characterization of the block copolymers using the novel bifunctional initiator by RAFT and FRP technics: evaluation of the primary polymerization parameters.
- Author
-
Öztürk, Temel, Savaş, Bedrettin, Meyvacı, Ergül, Kılıçlıoğlu, Ali, and Hazer, Baki
- Subjects
- *
BLOCK copolymers , *DIBLOCK copolymers , *METHYL methacrylate , *ADDITION polymerization , *BENZOYL chloride , *POLYMERIZATION - Abstract
Synthesis of poly(styrene-b-methyl methacrylate) block copolymers were obtained via reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene using RAFT-macro agent. For this purpose, 4-bromomethyl benzoyl chloride was obtained using 4-methylbenzoyl chloride and N-bromosuccinimide. The mono functional bromomethyl benzoyl t-butyl peroxy ester (t-BuBP) was obtained by reaction of 4-bromomethyl benzoyl chloride with t-butyl hydroperoxide. Terminally brominated poly(methyl methacrylate) (PMMA-Br) was synthesized using t-BuBP and methyl methacrylate via free-radical polymerization. RAFT-macro agent was acquired by reaction of PMMA-Br and potassium ethyl xanthogenate. By reacting RAFT-macro agent and styrene, block copolymers were obtained. The primary parameters, for example concentration, and time that affect reaction were evaluated. The products were characterized by FT-IR, 1H-NMR, GPC, and TGA. The multi instruments studies of the obtained block copolymers show that the copolymers easily formed as a result of RAFT. Mn,GPC values of the copolymers were between 24,900 g.mol−1 and 74,100 g.mol−1. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
44. An Alternative Chemical Approach for Development of Polymeric Analytical Platforms
- Author
-
Hosseini, Samira, Ibrahim, Fatimah, Kacprzyk, Janusz, Series editor, Hosseini, Samira, and Ibrahim, Fatimah
- Published
- 2016
- Full Text
- View/download PDF
45. Surface functionalization of cellulose fibers and exploration of its influence in ion exchange chromatography
- Author
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Wessén, Anna and Wessén, Anna
- Abstract
Kromatografiska metoder kan användas för en mängd olika tillämpningar, inklusive separation, rening och analys av biomolekyler och kemikalier. Membrankromatografi är en av de nya kromatografiteknikerna som expanderar snabbt eftersom den tillåter hög masstransport genom den stationära fasen, vilket resulterar i en mer tidseffektiv process. Med en kortare processtid är det möjligt att få en mer kostnadseffektiv metod. Ytförlängning är ett verktyg för att ytterligare förbättra materialets egenskaper genom att utöka ytan. Generering av sådana nya material genom polymerisation är mycket fördelaktigt eftersom det erbjuder ett justerbart tillvägagångssätt för variabla kombinationer, inklusive olika kombinationer av monomer och ymppunkter, vilket resulterar i ett teoretiskt brett bibliotek av membranegenskaper. Jonbyteskormatografi är en vanlig metod för separation av biomolekyler. Separationen är baserad på jonbytesinteraktioner mellan nettoladdningarna på målmolekylen, föroreningar (etc.) och den kromatografiska stationära fasen. Genom att derivatisera den stationära fasen med ytförlängare är det möjligt att inkludera laddade och neutrala monomerer genom sampolymerisation. Förlängningen ger möjlighet att öka antalet bindingsställen på den stationära fasen, vilket förbättrar materialets bindingskapacitet och potentiellt möjliggör en mer effektiv separation. Syftet med studien var att konstruera ett stationärt membranmaterial för jonbyteskromatografi med hög jonkapacitet och bibehållet lågt mottryck vid höga flödeshastigheter. Ett cellulosabaserat membran har derivatiserats genom ympning med fri radikalpolymerisation av syntetiska polymerer. Prototyper med olika sammansättningar, inklusive anjoner, katjoner och neutrala monomerer har utvärderats. Analys av prototyperna inkluderar mätningar av tryck/flödesegenskaper, jonkapacitet, med tillägg av kompletterande bilder av den morfologiska topografin med hjälp av svepelektronmikroskop på utvalda prototyper. Resultatet visar att, Chromatographic methods can be utilized for a variety of applications, including separation, purification, and analysis of biomolecules and chemicals. Membrane chromatography is one of the novel chromatography technologies that is rapidly expanding since it allows high mass transport through the stationary phase which is resulting in a more time-efficient process. With shorter process time, it is possible to get a more cost-effective method. Surface extension is a tool to further improve the properties of the material by extending the surface area. The generation of such new materials through copolymerization is highly advantageous as it offers a tuneable approach of variable combinations, including different combination of monomers and grafting points, resulting in a theoretically wide library of alterations of membrane properties. Ion-exchange chromatography is a common method for separation of biomolecules. The separation is based on ionic interactions between the net charges of the target molecule, contaminants, etc., and the chromatographic stationary phase. By derivatizing the stationary phase with surface extenders, it is possible to include charged- and neutral monomers by copolymerization. The extension provides the possibility to increase the number of binding sites on the stationary phase, which improves the binding capacity of the material and potentially allows a more efficient separation. The aim of the study was to construct a stationary membrane material for ion exchange chromatography with high ion capacity and maintained low backpressure at high flow rates. Cellulose-based membranes have been derivatized by surface grafting with free radical polymerization of synthetic polymers. Prototypes with different compositions, including anions, cations, and neutral monomers have been evaluated. Analysis of the prototypes includes measurement of the pressure/flow properties, ion capacity, and complementary images of the morphological topography using a scan
- Published
- 2023
46. Facile synthesis of graft copolymers containing rigid poly(dialkyl fumarate) branches by macromonomer method.
- Author
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Sato, Eriko, Tamari, Noboru, and Horibe, Hideo
- Subjects
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GRAFT copolymers , *COPOLYMERIZATION , *BLOCK copolymers , *ADDITION polymerization , *INTRINSIC viscosity , *DIMETHYL sulfate - Abstract
Graft copolymers show microphase separated structure as seen in block copolymers and have lower intrinsic viscosity than block copolymers because of a branching structure. Therefore, considering molding processability, especially for polymers containing rigid segments, graft copolymers are useful architectures. In this work, graft copolymers containing rigid poly(diisopropyl fumarate) (PDiPF) branches were synthesized by full free‐radical polymerization process. First, synthesis of PDiPF macromonomers by addition‐fragmentation chain transfer (AFCT) was investigated. 2,2‐Dimethyl‐4‐methylene‐pentanedioic acid dimethyl ester was found to be an efficient AFCT agent for diisopropyl fumarate (DiPF) polymerization because of the suppression of undesired primary radical termination, which significantly took place when common AFCT agent, methyl 2‐(bromomethyl)acrylate, was used. Copolymerization of PDiPF macromonomer with ethyl acrylate accomplished the generation of the graft copolymer having flexible poly(ethyl acrylate) backbone and rigid PDiPF branches. The graft copolymer showed a microphase separated structure, high transparency, and characteristic thermal properties to PDiPF and poly(ethyl acrylate). © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2474–2480 [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
47. 超疏水PE>HD/麦秸秆纤维复合材料的制备及其性能.
- Author
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侯成敏, 王梅, 张效林, 李娜, and 卓光铭
- Abstract
Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2019
- Full Text
- View/download PDF
48. A reduced-order multiscale model of a free-radical semibatch emulsion polymerization process.
- Author
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Urrea-Quintero, Jorge-Humberto, Ochoa, Silvia, and Hernández, Hugo
- Subjects
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MONTE Carlo method , *MULTISCALE modeling , *REDUCED-order models , *ADDITION polymerization , *PARTICLE size distribution , *EMULSION polymerization , *FREE radicals - Abstract
Free-radical emulsion polymerization is a heterogeneous process where simultaneous and competitive physicochemical events occur over a wide range of time/length scales. Although a highly accurate representation of the process is possible by multiscale modeling, common approaches face several issues, including the stochastic nature of finer scales, the timely exchange of information between scales, and the high computational load for the model solution. In this work, a reduced-order computationally-tractable multiscale model is proposed while preserving a good predictive capability. The model integrates microscopic-scale calculations based on kinetic Monte Carlo simulations (stochastic), a mesoscopic-scale representation of the particle size distribution through a novel statistical approach and a deterministic description of the macroscopic-scale. The proposed model resulted in faster satisfactory predictions (compared to the model based on the Fokker Planck Equation) of traditional macro and mesoscopic variables, along with the average number of free radicals and secondary nucleation on a microscopic scale. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
49. A geometric observer design for a semi-batch free-radical polymerization system.
- Author
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Salas, S.D., Romagnoli, J.A., Tronci, S., and Baratti, R.
- Subjects
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ADDITION polymerization , *POLYMERIZATION reactors , *MOLECULAR weights , *SIGNAL processing , *NONLINEAR estimation , *BATCH reactors - Abstract
In this work, a geometric observer (GO) is formulated and tested using experimental data from the Automatic Continuous Online Monitoring of Polymerization reactions (ACOMP) system for a semi-batch free-radical polymerization reactor that synthetizes polyacrylamide. The available measurements include the weight-average molecular weight, the concentration of monomer, and the volume of internal contents. Different combinations between innovated states and measurements offer a number of possible structures of the GO. The computation of the minimum singular values and condition numbers permit to select the most promising structures. To overcome inadequacies observed in full-order architectures, low order GOs with passive structures are explored. The best observer is selected, compared with a standard estimation strategy and tested under various experimental operating conditions. The observer performance is evaluated qualitatively and quantitatively as a tradeoff between dynamic property estimation and signal processing. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
50. Highly sensitive and selective dopamine determination using a photoelectrochemical sensor based on the BiVO4 and surface molecularly imprinted poly(acrylic acid-co-TRIM) on vinyl functionalized carbon nanotubes.
- Author
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Gorla, Felipe Augusto, do Prado Ferreira, Milena, dos Santos, Caroline Santana, de Matos, Roberto, Segatelli, Mariana Gava, and Tarley, César Ricardo Teixeira
- Subjects
- *
IMPRINTED polymers , *CARBON nanotubes , *CITRIC acid , *DOPAMINE , *CARBON electrodes , *VINYL polymers , *DETECTORS , *VITAMIN C - Abstract
• A nanocomposite BiVO 4 /MWCNT/MIP was developed for photoelectrochemical determination of dopamine. • A synergic effect of BiVO 4 and MWCNT/MIP was noticed. • The PEC sensor was selective towards the dopamine even in the presence of other compounds. This paper describes the development of a new photoelectrochemical (PEC) sensor for dopamine (DA) determination based on the nanocomposite constituted of a molecularly imprinted poly(acrylic acid- co -TRIM) functionalized onto MWCNT with vinyl groups (MWCNT-MIP) physically mixed with monoclinic bismuth vanadate. Synthesized polymeric materials were characterized by FT-IR, TGA, SEM and TEM. The sensor based on glassy carbon electrode modified with BiVO 4 /MWCNT-MIP provided a limit of detection (LOD) of 31.1 nmol/L and a linear range from 103.6 to 2500 nmol/L. The proposed sensor exhibited selectivity to DA in competitive analysis with epinephrine, norepinephrine, ascorbic acid, citric acid, uric acid, creatine and urea, and it was applied for analysis of DA in simulated urine samples using external calibration curve with accuracy attested by recovery values between 91 and 106 %. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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