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Red elemental nano-selenium, which is an important biological form of selenium, exhibits very low toxicity and remarkable biological properties and thus has several positive effects. For instance, it shows antioxidation and antistress characteristics, promotes growth and improves immunity. However, owing to its nanoscale size, it is very difficult to disperse and stabilize during synthesis and storage. In this study, nanoscale selenium with a mass content of 2.06% and an average particle size of 49 nm was prepared by the chemical reduction method. The analysis demonstrated that the surface phospholipids formed lamellar structures after directional freezing, and the nano-selenium particles were distributed in the middle of the lamellar. The nano-selenium particles were efficiently dispersed due to their lamellar structure and amphiphilicity. The particles displayed excellent stability and remained relatively unchanged after 20 days of storage in solution or solid state. The difficulties associated with the dispersion and storage stability of nanometer selenium during preparation were solved.

In this paper, a novel composite is constructed as a non-enzymatic hydrogen peroxide (H2O2) sensor by liquid-phase exfoliation method, which is composed of silver, copper oxide and cuprous oxide-doped a few layers graphene (CuxO/Ag@FLG). Its surface morphology and composition are analyzed by scanning electron microscopy (SEM) and X-ray photo spectroscopy (XPS), and its H2O2 sensing performance include catalytic reduction and quantitative detection is studied with electrochemical method. Our sensor had a high sensitivity of about 1272.62 μA mM-1 cm-2 (R2=0.9923) in a extremely wide range of concentrations from 10 μM to 20 mM H2O2, a fast response (about 5 s) and low limit of detection (S/N=3) of 2.13 μM. The sensor exhibits outstanding selectivity in the presence of various biological interference, such as dopamine, ascorbic acid, uric acid, citric acid, etc. In addition, the constructed sensor continued 95% current responsiveness after one month of storage further points to its long-term stability. Last but not least, it has a good recovery rate in the milk sold on the open market, indicating that it has a wide range of application possibilities in the food industry and biological medicine.

In this study, reduced graphene oxide (rGO)/boron nitride (BN) anisotropic aerogels (CGAs) used as the heat conduction network were prepared by one-step heat flow method to improve the low thermal conductivity and low heat transfer efficiency of phase change materials. Composite phase change materials (CPCMs) were obtained after vacuum adsorption of paraffin. The structure and thermal properties of the samples were then characterized. The results showed that the anisotropic aerogel was successfully prepared and the corresponding CPCM axial thermal conductivity was 1.68 W/(m K) when the graphene oxide (GO)/BN used to prepare the CGA was 1:20, which was 504% higher than pure paraffin. After 50 cycles, the paraffin leakage rate was 3.1%, and the enthalpy loss rate was 2.7%. When simulating the actual temperature change, the paraffin phase change time could be advanced by approximately 1210 s, and the paraffin phase change efficiency could be improved by approximately 47%. CPCMs have high thermal conductivity, high heat transfer efficiency, and high thermal conduction network stability. They exhibit high heat transfer efficiency and can be used in the fields of thermal energy storage and solar energy conversion and so on.

An approach of largely improving the properties of protein-based biopolymers is reported. Cottonseed protein concentrate (CPC) purified from cottonseed protein powder waste, with a protein content of >70% and a plasticizing efficiency of 4.2, was used to produce bioplastic polymer. A prepreg consisting of relatively oriented sisal fiber (SF) was transferred into CPC matrix as reinforcement, giving rise to improved mechanical properties of CPC/SF composites. To enhance interfacial bonding forces between the fiber and polymer, dialdehyde starch, DAS, with varied content (5–30 wt%) was introduced, and the FTIR and NMR results showed that DAS can effectively bridge biomacromolecular chains and form strong chemical bonds within the crosslinked structure. This cross-linking treatment leads to the formation of tight CPC/SF interfaces with strong adhesion, as shown by microscopic images, translating into excellent mechanical performance (e.g. tensile strength 21 MPa), water resistance (e.g. water contact angle 80°) and thermal stability (e.g. glass transition temperature 104 °C) of the composites. The all green composites derived from natural resources with comparable or even superior properties to state-of-the-art biomass-based composites hold great potential for being utilized in larger industries.

In view of their advantages (plasticity, low density, adjustable pore size, high porosity of >99.9%), three-dimensional graphene aerogels (GAs) are widely used for energy storage and adsorption separation, which has inspired the development and optimization of the corresponding synthetic techniques. In particular, self-assembly in the liquid phase features the benefits of tunability and sustainability and is viewed as a promising strategy of GA synthesis. During hydrothermal GA preparation, hydrophilic graphene oxide (GO) gradually turns lipophilic upon reduction, and the resulting phase transition separation and polarity change induce self-assembly into an aerogel. However, the effect of solution polarity on the structure or state of dispersed GO nanosheets, which affects the final property-determining process of automatic assembly, is still unclear. Herein, we prepared a series of GAs by hydrothermal reduction of unwashed GO with vitamin C in liquid-phase systems of different polarity and investigated the effects of polarity on the self-assembly process and aerogel properties using a range of instrumental techniques. The results showed that GO reduction is slowed down in weakly polar systems and further demonstrated that the shape of partially reduced graphene oxide (rGO) flakes depends on solution polarity. Flaky, layered, and stacked rGO particles obtained in strongly polar media self-assembled into anisotropic gully aerogels that were brittle and almost completely inelastic. Conversely, in weakly polar media, the prepared rGO sheets were twisted, which increased the number of contact points and modes between sheets and resulted in self-assembly into uniform-pore-structure honeycomb aerogels that showed good elasticity and could be repeatedly compressed.

Transparent and easily fabricated films were obtained through the coupling of eugenol, a bio-sourced feedstock, and poly(methylhydrosiloxane), via the Piers–Rubinsztajn reaction and Pt-catalysed hydrosilylation. The precursor reagents are readily available and economical, and the reaction process used was mild and easily undertaken. Additionally, poly(methylhydrosiloxane), having an abundant source of pendant Si–H groups, can be cross-linked with eugenol at multiple juncture points, and thus the eugenol content in these films ranges from 13.12 to 45.42 wt%. It was found that as the eugenol content increased, the thermal stability of the films also improved, with T10% and Rw at 700 °C ranging from 350.1 to 584.3 °C and 46.41 to 86.63%, respectively, which is higher than other analogous biomass-derived polysiloxanes. Crucially, the prepared films also exhibited suitable optical properties, with a >90% transmittance within the 430–1100 nm region and near 100% absorbance in the UV region ( 1.5) LED encapsulants and also in stacked multi-layer reflectors. In addition, to protect the encapsulated chips from moisture erosion, these films exhibit good water vapour barrier properties and water repellence.

In this study, we investigated the directional heating of graphene oxide (GO) dispersion to generate a temperature gradient and form a simulated &ldquo, ocean current&rdquo, inside the dispersion so that GO sheets could be aligned in a directional manner and then reduced and self-assembled into anisotropic reduced graphene oxide (rGO) gel. After freeze-drying and varying degrees of vacuum microwave treatment, anisotropic chemically derived graphene aerogels (AGAs) were obtained. Through performance detection and the analysis of the results, it was verified that the AGAs with certain characteristics of &ldquo, were prepared in this experiment, and its axial direction has obvious directional arrangement. After being treated by vacuum microwave for a short time (1 min.), the axial thermal conductivity of the composite materials (AGA-adsorbed paraffin) was observed to be 1.074 W/mK, and the thermal conductivity enhancement efficiency was 995%, as compared with similar thermal conductivity enhancement composites that were found in previous studies, the proposed method in this paper has the advantages of simple processing, high efficiency, and energy conservation.

In view of their advantages (plasticity, low density, adjustable pore size, high porosity of99.9%), three-dimensional graphene aerogels (GAs) are widely used for energy storage and adsorption separation, which has inspired the development and optimization of the corresponding synthetic techniques. In particular, self-assembly in the liquid phase features the benefits of tunability and sustainability and is viewed as a promising strategy of GA synthesis. During hydrothermal GA preparation, hydrophilic graphene oxide (GO) gradually turns lipophilic upon reduction, and the resulting phase transition separation and polarity change induce self-assembly into an aerogel. However, the effect of solution polarity on the structure or state of dispersed GO nanosheets, which affects the final property-determining process of automatic assembly, is still unclear. Herein, we prepared a series of GAs by hydrothermal reduction of unwashed GO with vitamin C in liquid-phase systems of different polarity and investigated the effects of polarity on the self-assembly process and aerogel properties using a range of instrumental techniques. The results showed that GO reduction is slowed down in weakly polar systems and further demonstrated that the shape of partially reduced graphene oxide (rGO) flakes depends on solution polarity. Flaky, layered, and stacked rGO particles obtained in strongly polar media self-assembled into anisotropic gully aerogels that were brittle and almost completely inelastic. Conversely, in weakly polar media, the prepared rGO sheets were twisted, which increased the number of contact points and modes between sheets and resulted in self-assembly into uniform-pore-structure honeycomb aerogels that showed good elasticity and could be repeatedly compressed.

Reported tensile mechanical properties of many natural plant fibres vary to a large extent due to very often inappropriate measurement of the fibre’s cross-sectional area by diameter estimation. Using natural ramie filament as a model testing elementary fibre, a more realistic stereological determination is presented, including microscopic imaging analysis of the fibres’ cross-sectional area. When applying the area data using this approach to calculate tensile strength, a far narrower variation in the fibres’ strength distribution according to Weibull analysis was found. The gauge length effects on the mechanical performance of the natural fibre were revealed and analysed. In addition, in situ SEM observations during microtensile measurements detected real time changes in the fibres’ structure during stress. It was found that fibre failure was mainly caused by macroscopic physical defects and associated microscopic slippage of the microfibrils. Furthermore, results of cyclic tensile tests indicated that the fibre underwent elastic deformations under progressive loading–unloading cycles, which is due to bonding restriction that the surrounding matrix presents against the slippage of the microfibrils and reorganisation of hydrogen bonds. Graphical abstract: [Figure not available: see fulltext.]., The authors are thankful for financial support from the National Natural Science Foundation of China (21706039, 21676058) and the Natural Science Foundation of Guangdong Province (2017A030310300, 2016A030313694). PSS also gratefully acknowledges the Spanish Ministry Economy and Competitivity (MINECO) for a Ramón y Cajal fellowship (RYC-2014-16759) and a Proyecto de Investigación en el Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia (MAT2017-88382-P). We are grateful to Dr. Alvaro Ridruejo and Editor Alfred D. French, Ph.D. for their kind suggestion and discussion

Feather, as a by-product of the poultry industry, has long been treated as a solid waste, which causes environmental and economic problems. In this work, the hydrolyzed feather keratin (HFK) was extracted from the chicken feather using a cost-effective method of alkali-extraction and acid-precipitation by applying urea and sodium sulfide. The aim was development and characterization of the eco-friendly films based on the HFK with variable glycerol contents by a thermoplastic process. The thermal analysis showed that high temperature and high pressure improved the compatibility between the glycerol and the HFK molecules. Also it was shown that the addition of water is necessary in the hot-pressing process of films. The FT-IR analysis indicated that the formation of the new hydrogen bonds between HFK and glycerol. By increasing the glycerol content, the film tensile strength ( σ b ) decreases from 10.5 MPa to 5.7 MPa and the solubility increases from 15.3% to 20.9%, while the elongation at break ( e b ) achieves the maximum value of 63.8% for the film with 35% glycerol. The swelling was just below 16.9% at 25 °C for 24 h, suggesting a good stability of the films in water. The water vapor permeability (WVP) varied between 3.02 × 10 − 10 g · m − 2 · s − 1 · Pa − 1 and 4.11 × 10 − 10 g · m − 2 · s − 1 · Pa − 1 for the films with 20% and 40% glycerol, respectively. The HFK film was uniform, translucent and tough, which could be used in packaging and agricultural field.

With the increasing energy and environmental problems, photoelectrochemical (PEC) water splitting has recently attracted a great deal of attention. Herein, we report the facile synthesis of CdS/WO3 heterostructures as high-performance photoanodes for PEC water splitting. CdS/WO3 heterostructures are successfully prepared on F doped SnO2 glass substrates by a two-step process, which involves a hydrothermal growth and electrochemical deposition process. In comparision to pristine WO3 nanostructures, CdS/WO3 heterostructures exhibit substantially high harvesting ability. The CdS/WO3 heterostructures yield a significant photocurrent density of 1.8 mA cm−2 at 0 V vs. Ag/AgCl, which is substantially higher than that of bare WO3 and CdS electrodes. These findings will open up new opportunities to develop other efficient solar-light-driven photocatalytic cells.

In this study, feather keratin/polyvinyl alcohol/tris(hydroxymethyl)aminomethane (FK/PVA/Tris) bionanocomposite films containing graphene oxide (GO) (0.5, 1, 2, and 3 wt%) or graphene (0.5, 1, 2, and 3 wt%) were prepared using a solvent casting method. The scanning electron microscopy results indicated that the dispersion of GO throughout the film matrix was better than that of graphene. The successful formation of new hydrogen bonds between the film matrix and GO was confirmed through the use of Fourier-transform infrared spectroscopy. The tensile strength, elastic modulus, and initial degradation temperature of the films increased, whereas the total soluble mass, water vapor permeability, oxygen permeability, and light transmittance decreased following GO or graphene incorporation. In summary, nanoblending is an effective method to promote the application of FK/PVA/Tris-based blend films in the packaging field.

The development of edible films based on the natural biopolymer feather keratin (FK) from poultry feathers is of great interest to food packaging. Edible dialdehyde carboxymethyl cellulose (DCMC) crosslinked FK films plasticized with glycerol were prepared by a casting method. The effect of DCMC crosslinking on the microstructure, light transmission, aggregate structure, tensile properties, water resistance and water vapor barrier were investigated. The results indicated the formation of both covalent and hydrogen bonding between FK and DCMC to form amorphous FK/DCMC films with good UV-barrier properties and transmittance. However, with increasing DCMC content, a decrease in tensile strength of the FK films indicated that plasticization, induced by hydrophilic properties of the DCMC, partly offset the crosslinking effect. Reduction in the moisture content, solubility and water vapor permeability indicated that DCMC crosslinking slightly reduced the moisture sensitivity of the FK films. Thus, DCMC crosslinking increased the potential viability of the FK films for food packaging applications, offering a value-added product.

With developments of the electronics industry, more components are being included in electronic devices, which has led to challenges in thermal management. Using reduced graphene oxide embedded with MQ silicone resin (RGO/MQ) nano-aggregates as the composite filler and silicone rubber (SR) as the matrix, a simple approach is designed to prepare RGO/MQ/SR composites. Reduced graphene oxide (RGO) was first used as a substrate for the growth of MQ silicone resin by hybridization, forming sandwich-like micro structured RGO/MQ nano-aggregates successfully. Then, RGO/MQ was integrated into &alpha, &omega, dihydroxylpolydimethylsiloxane based on the in situ solvent-free blending method, followed by condensation and vulcanization, fabricating the final RGO/MQ/SR composites. The effective strategy could enhance the adaptability between graphene and silicone matrix under external stimuli at room temperature by embedding nanoscale MQ into the interface of graphene/silicone as the buffer layer. Obvious improvements were found in both thermal conductivity and mechanical properties due to excellent dispersion and interfacial compatibility of RGO/MQ in the host materials. These attractive results suggest that this RGO/MQ/SR composite has potential as a thermal interface material for heat dissipation applications.

Feather keratin (FK) extracted from feathers represents a valuable source of biodegradable and biocompatible polymer. The aim of this study was the development and characterization of blended films based on FK and polyvinyl alcohol (PVA) cross-linked by dialdehyde starch (DAS) for a potential drug release application. The compatibility of FK/PVA was improved when cross-linked by DAS: the relative crystallinity of the PVA/FK film slightly decreased, and the enthalpy value for the melting peak decreased by about 50% for the cross-linked films. The total soluble mass of all blend films in water was below 35% at 37 °C, indicating a good stability of the films in water. The results of the Rhodamine B dye (as a model drug) release tests showed that the release rates decreased with increasing DAS content. DAS-induced cross-linking improves several important properties of the FK/PVA films, such as the compactness, the compatibility, and the stability in water. These improvements offer the potential to expand the application of FK films in the biomaterial field.

A magnetic nano-supported Cu(I) catalyst was prepared and showed high activity for cyclization of ene-yne-ketone to synthesize furans. The catalyst was easily recovered from the reaction by using external magnets and reused 8 times without significant loss of its catalytic activity.

Feathers, a byproduct of the poultry industry, have long been considered as a solid waste, posing a series of environmental and economic problems. However, feather keratin (FK) extracted from feathers is a valuable source of the biodegradable and biocompatible polymer. The aim of this study was to develop and characterize novel casting films based on feather keratin (FK) crosslinked by dialdehyde starch (DAS) and plasticized with glycerol for applications in biomedicine. The microstructure, crystallization behavior, light transmission, moisture content, solubility, tensile properties, water vapor barrier property, and cytotoxicity of the FK–DAS films were investigated. The fracture surface of the crosslinked film showed a more compact microstructure than that of the control film, and the crosslinked films were completely amorphous and very transparent (transparency value

Feathers, as a by-product of the poultry industry, have long been treated as solid waste disposal which causes a series of environmental and economic problems. Feather keratin (FK) can be extracted from feathers and have very strong stretching resistance. A series blend films based on FK and poly (vinyl alcohol) (PVA) was prepared by solution casting, and dialdehyde starch (DAS) were introduced to achieve better physicochemical properties for the blend films. According to DSC analysis, the single glass transition temperature and single melting temperature of the blend films indicated the good compatibility among FK, PVA and DAS. With increasing PVA content, the tensile strength (σb), elongation at break (ϵb), and decomposition temperature increased, indicated that hydrogen bonds were formed between FK and PVA. With certain PVA content, the increase of DAS caused σb to increase and ϵb, decomposition rates, solubility and water vapor permeability (WVP) to decrease, suggesting the formation of crosslink netw...

Two polymerizable room temperature ionic liquids (RTIL), AMPS-BA and AMPS-DMAEMA, were synthesized by neutralization of 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) with butylamine (BA) and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), respectively, in acetone, followed by evaporation of the solvent under a reduced pressure at room temperature. The RTILs were characterized by differential scanning calorimetry to determine their glass transition temperatures (Tg). Co-polymeric gels of the RTILs with 2-hydroxyethylmethacrylate (HEMA) were prepared by aqueous solution polymerization using N,N′-methylenebisacrylamide (MBAm) as a cross-linker and ammonium persulfate as an initiator. The superabsorbency of the gels in water and various organic solvents was gravimetrically investigated. The results showed that the Tg of AMPS-BA and AMPS-DMAEMA was -47.7°C and -45.8°C, respectively. Poly(AMPS-BA-co-HEMA) gels exhibited superabsorbency in both water and various organic solvents, while poly(AMPS-DMAEMA-co-HEMA) gels did not swell in any liquids. The mechanism for the swelling difference between poly(AMPS-BA-co-HEMA) gels and poly(AMPS-DMAEMA-co-HEMA) gels was critically discussed.

The interpenetrating polymer network of fast temperature-responsive hydrogels based on soy protein and poly(N-isopropylacrylamide) were successfully prepared using the sodium bicarbonate (NaHCO3) solutions as the reaction medium. The structure and properties of the hydrogels were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermal gravimetric analysis. The swelling and deswelling kinetics were also investigated in detail. The results have shown that the proposed hydrogels had high porous structure, good miscibility and thermal stability, and fast temperature responsivity. The presence of NaHCO3 had little effect on the volume phase transition temperature (VPTT) of the hydrogels, and the VPTTs were at about 32?C. Compared with the traditional hydrogels, the proposed hydrogels had much faster swelling and deswelling rate. The swelling mechanism of the hydrogels was the non-Fickian diffusion. This fast temperature-responsive hydrogels may have potential applications in the field of biomedical materials.

In this study, anisotropic graphene/graphene oxide (GO) aerogels (AGAs) were obtained by freeze-drying after direct participation of pristine graphene in the self-assembly of anisotropic gel by the heat flow method. After vacuum microwave treatment, the physical, chemical and structural characteristics of the AGAs were investigated. The results show that AGAs, in which the internal graphene sheets are parallel to the heat flow direction, are successfully prepared. After microwave treatment, the amount of oxygen and nitrogen reduces significantly and the sp2 domain increases. However, at the same time, many fragments and holes are generated in the graphene sheets. The effects of AGAs on the phase transition of paraffin is studied, and the results show that the melting enthalpy, solidification enthalpy and initial melting temperature of AGA/paraffin composites decreases as the GO content in the AGAs increases, whereas the melting range, solidifying range and subcooling degree increases. The highest axial thermal conductivity of the AGA/paraffin composite is 1.45 W/(mK), and the thermal conductivity enhancement efficiency is 884% (AGA content was 0.53 vol %). Compared with previously investigated, similar AGA/paraffin composites, the aerogels fabricated in this study have the obvious advantages of a simple fabrication process, a low cost and a high thermal conductivity enhancement efficiency. These aerogels possess the potential for application in phase-change energy storage (PES), thermal energy management and other fields.

A novel sulfonate flame retardant, 1,3,5,7-tetrakis(phenyl-4-sodium sulfonate)adamantane (FR-A), was successfully synthesized from 1-bromoadamantane in sequential four-step reactions involving Fiedel-Crafts phenylation, sulphonation, hydrolysis, and neutralization. The success of synthesis was confirmed by FTIR spectra, NMR spectra, elemental analyses and mass spectra. The effect of FR-A on the flame retardacy of polycarbonate (PC) has been studied. Limiting oxygen index (LOI) and thermogravimetric analysis (TGA) showed that this novel sulfonate flame retardant had effective flame retardancy on polycarbonate (PC). With a small amount (0.08 wt%) of FR-A, the flame retardancy of PC was improved obviously, which got to UL 94 V-0 rating. TGA and DTA curves demonstrated that the additive raised the degradation rate of PC by promoting the quick formation of an insulating carbon layer on the surface, and confirmed that the flame retardant mechanism of PC/FR-A system was similar to potassium diphenylsulfone sulfonate (KSS).

In recent years, the unusual qualities such as high surface activity, low critical micelle concentration (CMC), and diverse aggregate structures of Gemini surfactants, which contain double hydropho...

Effective therapy lies in achieving a therapeutic amount of drug to the proper site in the body and then maintaining the desired drug concentration for a sufficient time interval to be clinically effective for treatment. The blood-brain barrier (BBB) hinders most drugs from entering the central nervous system (CNS) from the blood stream, leading to the difficulty of delivering drugs to the brain via the circulatory system for the treatment, diagnosis and prevention of brain diseases. Several brain drug delivery approaches have been developed, such as intracerebral and intracerebroventricular administration, intranasal delivery and blood-to-brain delivery, as a result of transient BBB disruption induced by biological, chemical or physical stimuli such as zonula occludens toxin, mannitol, magnetic heating and ultrasound, but these approaches showed disadvantages of being dangerous, high cost and unsuitability for most brain diseases and drugs. The strategy of vector-mediated blood-to-brain delivery, which involves improving BBB permeability of the drug-carrier conjugate, can minimize side effects, such as being submicrometre objects that behave as a whole unit in terms of their transport and properties, nanomaterials, are promising carrier vehicles for direct drug transport across the intact BBB as a result of their potential to enter the brain capillary endothelial cells by means of normal endocytosis and transcytosis due to their small size, as well as their possibility of being functionalized with multiple copies of the drug molecule of interest. This review provids a concise discussion of nano carriers for drug transport across the intact BBB, various forms of nanomaterials including inorganic/solid lipid/polymeric nanoparticles, nanoemulsions, quantum dots, nanogels, liposomes, micelles, dendrimers, polymersomes and exosomes are critically evaluated, their mechanisms for drug transport across the BBB are reviewed, and the future directions of this area are fully discussed.

The adsorption behaviors of copper and lead ions in aqueous solution by cottonseed protein-poly (acrylic acid) copolymer (CP-PAA) hydrogel composite have been studied in single component sorption systems. The influence of cottonseed protein content in the copolymer composition on the adsorption capacity of the hydrogel is studied and the sorption of copper (II) and lead (II) ions is investigated in aqueous solution with different initial metal ion concentration and pH value, respectively. The results indicate that the hydrogel composite is a suitable sorbent for the two metal ions. The experimental data of the adsorption equilibrium from Cu(II) and Pb(II) solution correlated well with the Langmuir isotherm equation. The adsorption kinetics of the two metal ions has been analyzed and the pseudo–second-order equation provides good fits to experimental data of both metals. By treatment with aqueous HCl solution, the hydrogel can be regenerated and reused again to adsorb heavy metal ions. The characterization...

Crosslink polymerization kinetics of poly(acrylic acid-co-2-acrylamido-2-methylpropane sulfonic acid), AA/AMPS hydrogels, was investigated by using dilatometry in the presence of sodium persulfate as initiator and N , N ′-methylene bis(acrylamide) as crosslinker. It was found that the reaction for the crosslink polymerization of AA/AMPS hydrogels had orders of 0.58, 1.14, and 0.86 with respect to the initiator, AMPS, and AA, respectively. From the Arrhenius plots, the activation energy of the crosslink polymerization was found to be about 140 and 89 kJ·mol −1 in the presence and absence of the crosslinker, respectively, in the temperature range from 45 to 65 °C. It was noted that the crosslinker had effects on the reaction order of the initiator and the activation energy due to the formation of cross-linked networks, which was verified by Fourier transfer infrared (FTIR) spectrum. To further confirm the influences of the cross-linked network structure on kinetic parameters of the crosslink polymerization, a mechanism was proposed, which highlights the different termination routes between free radical polymerization and crosslink polymerization. These results suggest that dilatometry provides a convenient tool for crosslink polymerization study, and confirm that the cross-linked networks are formed in the crosslink polymerization.

A series of the thermosensitive interpenetrating polymer network hydrogels composed of soy protein and poly(N-isopropylacrylamide) were successfully prepared. The structure and properties were systematically characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and differential scanning calorimetry. It was found that the hydrogels had good miscibility and high porosity, and the volume phase transition temperatures of the hydrogels were around 32°C. The release behavior and the release mechanism of a model protein, bovine serum albumin (BSA), were also investigated in detail. The results indicated that the release behavior of BSA had strong temperature dependence and the release percentage of BSA could be controlled by modulating the amount of soy protein or crosslinking agent. The analysis of the release mechanism revealed that the Fickian diffusion controlled release was dominant under the experimental conditions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Copolymers of poly(silphenylene–siloxane) with dimethylsiloxane and diphenylsiloxane with various end groups were synthesized through an SiH/SiOR polycondensation process. The thermooxidative degradation behaviors of the copolymers were investigated by thermogravimetric analysis and IR spectrometry techniques. All of the polymers were characterized by a two-step mass loss. The first one, which peaked at 510–545°C in differential thermogravimetric curves, was mostly caused by the main-chain depolymerization, whereas the second one, which reached its maximum around 650°C, was caused by side-group oxidation and SiC bond scission. The main-chain depolymerization occurred over a temperature range of some 470–580°C, whereas SiC bond scission and side-group oxidation occurred over a temperature range of about 585°C to above 720°C. The incorporation of phenyl groups in the end groups greatly retarded the temperature for the degradation onset of the main chain to 120°C higher. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Most acrylic acid-based superabsorbent hydrogels, which have been widely used in many applications, are crosslinked with water-solvable crosslinker N,N-methylenebisacrylamide (NMBA), which is easy to hydrolyze when radiated by ultraviolet, leading to decomposition of the superabsorbent hydrogels. In this article, ultraviolet-induced decomposition of acrylic acid-based superabsorbent hydrogels crosslinked with NMBA was investigated by weight loss method under ultraviolet radiation. The results showed that the decomposition rate of the superabsorbent hydrogels was controlled by ultraviolet-induced activation of amide groups on the networks when the intensity of ultraviolet radiation was low, whereas it was controlled by hydrolysis of amide groups on NMBA molecules when the intensity of ultraviolet radiation was high. The ultraviolet stability of acrylicacid-based superabsorbent hydrogels crosslinked with NMBA can be improved by increasing the neutralization degree of acrylic acid, increasing the dosage of crosslinker NMBA, or introducing acrylamide as comonomer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

In this article, poly(2-hydroxyethylmethacrylate-co-acrylamide) hydrogels were synthesized by bulk free-radical copolymerization of 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) for soft contact lens(SCL)-based ophthalmic drug delivery system. The copolymer was characterized with FT-IR and SEM, the swelling property of the hydrogels were studied by gravimetrical method, and chloramphenicol was used as a model drug to investigate drug release profile of the hydrogels. The results showed that poly(2-hydroxyethylmethacrylate- co-acrylamide) hydrogels were transparent and useful SCL biomaterial, the water content increased as AAm content increase and pH decrease, and in the same way, hydrogel composition affected chloramphenicol release process too. Migration rate of chloramphenicol increased as the AAm content in the hydrogels increased in the first stage of diffusion process, whereas there was no significant difference thereafter.

This work examines the interfacial structure and interaction between water and polymer chains in the hydrogel–hydrogel composites with the goal of establishing foundations for further investigation of drug diffusion from one hydrogel to another in the soft contact lens. This is based on the ability of the hydrogel–hydrogel composites to release ophthalmic drugs in a sustained manner. The hydrogel–hydrogel composites were synthesized by immersing the glycerol-swollen particles of crosslinked N-vinyl-2-pyrrolidone (NVP) into the monomer of hydroxyethylmethacrylate (HEMA) containing initiator benzoylperoxide (BPO) that polymerizes to form a matrix in the presence of the first networks. The hydrogel–hydrogel composites were characterized by UV/Vis spectrophotometer, scanning electronic micrography (SEM), and differential scanning calorimetry (DSC). The results showed that the samples of hydrogel–hydrogel composites of the particles of crosslinked NVP and poly-HEMA were transparent and glassy and suitable for soft contact lens. Three types of the interfacial structure, no interpenetrating interface, partly interpenetrating interface, and fully interpenetrating interface, of the hydrogel–hydrogel composites existed, and the type of the interfacial structure was determined by the degree to which the monomer of HEMA penetrated into the first networks before formation of the matrix. Different from poly-HEMA hydrogels, the peaks near 0°C on DSC curves of the hydrogel–hydrogel composites did not split while they were kept acute, and the amount of freezable-bound water was less. This shows that the water incorporated in the hydrogel–hydrogel composites does not strongly interact with polymer matrix, so the hydrogel–hydrogel composites cannot keep their shape during the phase transition of water. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

E-mail: cuigdut@yahoo.com.cnReceived April 8, 2013, Accepted May 13, 2013A convenient Rh-catalyzed C-H arylation of imidazo[1,2-a]pyridines with a variety of aryl halides or triflateshas been reported. This process afforded a range of biaryl compounds in excellent yields and showed highactivity and broad scope. Key Words : Rhodium catalyst, Aryl halides, Regioselective arylation, Imidazo[1,2- a]pyridines, TriflatesIntroductionHeteroaromatics bearing aryl-heteroaryl bond are alwaysas one of the most important structural units frequentlyfound in biological compounds, natural products, materialschemistry, ligands.

As a nanoparticle support material, carbon nanotubes (CNTs) provide a certain potential activation of catalysis in heterogeneous catalytic organic reactions. Herein, an efficient Ag/CNT-catalyzed synthesis of enamines via hydroamination of activated alkynes with aromatic amines has been described. This catalyst still retains catalytic activity after being recycled and reused three times. In addition, it represents a green and environmentally friendly process for preparation of enamines. Copyright © 2013 John Wiley & Sons, Ltd.

Thermomechanical relaxation events and different water states in cottonseed protein bioplastics are presented whilst investigating the effects of aldehyde cross-linking agents. Thermomechanical relaxation of cottonseed protein bioplastics associated with protein denaturation, moisture absorption and broad glass transitions (Tg) were observed from DSC and DMA measurements. It was shown that variation of the aldehyde influences the storage modulus at very low temperature (below Tg). From measurements of the water fusion point, enthalpy, vaporisation, and weight loss, three water states in the water-absorbed bioplastics are suggested; namely strongly-bound-to-polymer, weakly-bound-to-polymer and bulk-like water. The water content and unreacted cross-linking agents are influential factors in controlling formation of the different water states, whilst the selection of different aldehydes was found to be negligible. These results could be valuable for adjusting the thermomechanical relaxations of protein based bioplastics, and tailoring their properties in wet environments.

3,3′-Bis(5,6-dibromomethyl-1,2,4-triazine), a new polyfunctional bipyridine analogue for constructing supramolecular structures, has been synthesized from 2,3-butanedione and oxylhydrazidine by two routes in moderate to high yields.

pH- and temperature-responsive interpenetrating polymer network (IPN) hydrogels based on soy protein and poly(N-isopropylacrylamide-co-sodium acrylate) were successfully prepared. The structure and properties of the hydrogels were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analyzer. The equilibrium and dynamic swelling/deswelling behaviors and the drug release properties of the hydrogels responding to pH and/or temperature were also studied in detail. The hydrogels have the porous honeycomb structures, good miscibility and thermal stability, and good pH- and temperature-responsivity. The volume phase transition temperature of the hydrogels is ca. 40°C. Changing the soy protein or crosslinker content could be used to control the swelling behavior and water retention, and the hydrogels have the fastest deswelling rate in pH 1.2 buffer solutions at 45°C. Bovine serum albumin release from the hydrogels has the good pH and temperature dependence. The results show that the proposed IPN hydrogels may have potential applications in the field of biomedical materials such as in drug delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39781.

3,3′-Bis(5,6-dibromomethyl-1,2,4-triazine), a new polyfunctional bipyridine analogue for constructing supramolecular structures, has been synthesized from 2,3-butanedione and oxylhydrazidine by two routes in moderate to high yields.

Taking 2-acrylamido-2-methylpropane sulfonic acid (AMPS) as monomer, taking N,N’-methylenebis acrylamide as the cross linker, and taking the potassium persulfate as the initiators, we adopted the aqueous polymerization to prepare the PAMPS hydrogel and studied the swelling kinetics and electric sensitive properties of the hydrogel. The results indicated that, the swelling process of PAMPS in deionized water exhibited a non-Fickian diffusion model. Applying 15 V contact voltage for 30 minutes, the minimum of mass maintenance rate of PAMPS was 36.82 %. Under noncontact continuous 15 V voltage applied periodically, the PAMPS showed a favorable reversible bending behavior.

Taking 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and 2-dimethylamino ethyl methacrylate (DMAEMA) as monomers, taking N,N’-methylenebis acrylamide as the cross linker, and taking the ammonium persulfate and sodium bisulfite as the redox initiators, we adopted the aqueous polymerization to prepare the Ploy(AMPS-co-DMAEMA) hydrogel and studied the shrinking and bending behaviors of hydrogel under exterior DC electric field stimulation. The result indicated that the DMAEMA monomer content and the pressure could significantly influence the electric sensitivity of hydrogel. With the increase of the DMAEMA content and the non-contract electric field, the Poly(AMPS-co-DMAEMA) hydrogel first bended toward the cathode and then bended toward the anode.

Under the condition of ultrasonic radiation, in this article, we studied the reaction kinetics of non-homogeneous phasechitin deacetylation. The results indicated that the deacetylation degree of chitin was obviously enhanced under thecondition of ultrasonic radiation, and the reaction process accorded with pseudo-first order kinetics relationship, and thereaction control is diffusion control, and the surface activation energy was E=23.45kJ/mol.