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Two new random donor-acceptor (D-A) copolymers, signed as P1 and P2, were designed and synthesized. Electrochemical and spectroelectrochemical measurements were performed to investigate absorption, energy levels, electronic and optical band gaps for comparison. The polymers were used as donor polymers in the active layer to fabricate non-fullerene, bulk heterojunction (BHJ) organic photovoltaics (OPVs). Investigations were carried out through the conventional BHJ structure; ITO/PEDOT: PSS/Active Layer/LiF/Al, where active layer consists of 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITIC) as the acceptor and thienopyrroledione containing donors. The device based on P1:ITIC(1:1) blend with a thickness of 161 nm gave the best performance with a power conversion efficiency (PCE) of 7.94%, an open-circuit voltage (V-OC) of 0.86 V, a short-current density (J(SC)) of 18.45 mA cm(-2) and a fill factor (FF) of 50.12%. The highest PCE obtained from P2 based organic solar cell is 1.96%. P2 exhibited low solubility attributed to the lack of alkyl groups enhancing polymer solubility, electronic properties, and photovoltaic performances. The research outputs exhibit that introduction of alkyl chains on the polymer backbone can enhance device performance. (C) 2021 Elsevier Ltd. All rights reserved.

The aim of this work is to investigate the preparation, the optical properties, and the stability over time of a colloidal organic–inorganic hybrid perovskite (CH3NH3PbBr3)/random copolymer P(MMA-co-DMAEMA) system. Different ratios of perovskite to copolymer were used to study its effect on stability and properties. The optical properties were investigated by UV-Vis and fluorescence spectroscopy. Dynamic light scattering was used to determine the size, and the size polydispersity of the colloidal hybrid particles; while morphology was investigated by transmission electron microscopy. Photoluminescence decay studies revealed the interaction of the random copolymer with the perovskite. Finally, thin-films were prepared, to investigate the optical properties of the samples in the absence of the solvent. High temporal stability of the optical properties of thin hybrid films was observed under certain conditions.

Methacrylate-benzodioxinone (BDMA) as a monomer was firstly synthesized and then copolymerized with methyl methacrylate and 2-hydroxyethyl methacrylate via atom transfer radical polymerization (ATRP) in the presence of CuCl/pentamethyldiethylene triamine (PMDETA) catalytic system using ethyl 2-bromopropionate (EtBrP) as an initiator. Successful formation of the block copolymer was also confirmed in detail by proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier-transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC) appropriately. Secondly, photochemical acylation of obtained copolymer through hydroxyl and benzodioxinone groups led to the release of benzophenone compound and ester-linkage on the polymer backbone. The formation of ester-linkage increases the glass transition temperature and the thermal stability of the obtained copolymer. © 2021, Turkish Chemical Society. All rights reserved.

Among the several actions contributing to the development of a sustainable society, there is the eco-design of new plastic materials with zero environmental impact but that are possibly characterized by properties comparable to those of the traditional fossil-based plastics. This action is particularly urgent for food packaging sector, which involves large volumes of plastic products that quickly become waste. This work aims to contribute to the achievement of this important goal, proposing new bio-based cycloaliphatic polymers based on trans-1,4-cyclohexanedicarboxylic acid and containing different amount of camphoric acid (from 0 to 15 mol %), a cheap and bio-based building block. Such chemical modification was conducted in the melt by avoiding the use of solvents. The so-obtained polymers were processed in the form of films by compression molding. Afterwards, the new and successfully synthesized random copolymers were characterized by molecular (NMR spectroscopy and GPC analysis), thermal (DSC and TGA analyses), diffractometric (wide angle X-ray scattering), mechanical (through tensile tests), and O2 and CO2 barrier point of view together with the parent homopolymer. The article aims to relate the results obtained with the amount of camphoric moiety introduced and to present, the different microstructure in the copolymers in more detail, indeed, in these samples, a different crystalline form developed (the so-called β-PBCE). This latter form was the kinetically favored and less packed one, as proven by the lower equilibrium melting temperature determined for the first time by Baur’s equation.

Structural relaxation in polymers occurs at temperatures in the glass transition range and below. At these temperatures, crystallization is controlled by diffusion and nucleation. A sequential occurrence of structural relaxation, nucleation, and crystallization was observed for several homopolymers during annealing in the range of the glass transition. It is known from the literature that all of these processes are strongly influenced by geometrical confinements. The focus of our work is copolymers, in which the confinements are caused by the random sequence of monomer units in the polymer chain. We characterize the influence of these confinements on structure formation and relaxation in the vicinity of the glass transition. The measurements were performed with a hydrogenated nitrile-butadiene copolymer (HNBR). The kinetics of the structural relaxation and the crystallization was measured using fast differential scanning calorimetry (FDSC). This technique was selected because of the high sensitivity, the fast cooling rates, and the high time resolution. Crystallization in HNBR causes a segregation of non-crystallizable segments in the macromolecule. This yields a reduction in mobility in the vicinity of the formed crystals and as a consequence an increased amount of so-called &ldquo, rigid amorphous fraction&rdquo, (RAF). The RAF can be interpreted as self-assembled confinements, which limit and control the crystallization. An analysis of the crystallization and the relaxation shows that the kinetic of both is identical. This means that the Kohlrausch exponent of relaxation and the Avrami exponent of crystallization are identical. Therefore, the crystallization is not controlled by nucleation but by diffusion and is terminated by the formation of RAF.

Stimuli-responsive polymers have attracted significant interest in the fields of advanced materials and biomaterials. Herein, temperature- and pH-responsive glycopolymers, which are composed of N-isopropylacrylamide, methacrylic acid, and an acrylamide derivative bearing a lactose moiety, were synthesized via radical copolymerization. The series of resulting glycopolymers had different degrees of substitution of the lactose moieties, were responsive to temperatures between 26.6 &deg, C and 47.6 &deg, C, and formed aggregates above the lower critical solution temperature limit in mild acidic aqueous media (pH 4&ndash, 6). The temperature-responsive behavior was dependent on the prevailing pH conditions, as no aggregation was observed in neutral and basic aqueous media (pH &gt, 7). The aggregates had saccharide moieties on the surface in aqueous media. The number of saccharide moieties on the surface depended on the saccharide-containing unit ratio in the glycopolymer. The ratio was determined via enzymatic hydrolysis of the lactose moieties using &beta, galactosidase and the subsequent detection of the released galactose.

Random copolymers made of both (PIM-polyimide) and (6FDA-durene-PI) were prepared for the first time by a facile one-step polycondensation reaction. By combining the highly porous and contorted structure of PIM (polymers with intrinsic microporosity) and high thermomechanical properties of PI (polyimide), the membranes obtained from these random copolymers [(PIM-PI)-(6FDA-durene-PI)] showed high CO2 permeability (&gt, 1047 Barrer) with moderate CO2/N2 (&gt, 16.5) and CO2/CH4 (&gt, 18) selectivity, together with excellent thermal and mechanical properties. The membranes prepared from three different compositions of two comonomers (1:4, 1:6 and 1:10 of x:y), all showed similar morphological and physical properties, and gas separating performance, indicating ease of synthesis and practicability for production in large scale. The gas separation performance of these membranes at various pressure ranges (100&ndash, 1500 torr) was also investigated.

A novel "symbiotic self-assembly" strategy that integrates the advantages of biocompatible lipids with a structurally robust polymer to efficiently encapsulate and deliver siRNAs is reported. The assembly process is considered to be symbiotic because none of the assembling components are capable of self-assembly but can form well-defined nanostructures in the presence of others. The conditions of the self-assembly process are simple but have been chosen such that it offers the ability to arrive at a system that is noncationic for mitigating carrier-based cytotoxicity, efficiently encapsulate siRNA to minimize cargo loss, be effectively camouflaged to protect the siRNA from nuclease degradation, and efficiently escape the endosome to cause gene knockdown. The lipid-siRNA-polymer (L-siP) nanoassembly formation and its disassembly in the presence of an intracellular trigger have been extensively characterized experimentally and through computational modeling. The complexes have been evaluated for the delivery of four different siRNA molecules in six different cell lines, where an efficient gene knockdown is demonstrated. The reported generalized strategy has the potential to make an impact on the development of a safe and effective delivery agent for RNAi-mediated gene therapy that holds the promise of targeting several hard-to-cure diseases.

Organic semiconductor (OSC):polymer blends are recently increasing their popularity due to the impressive performances they offer once employed as active layer in organic field-effect transistors (OFETs). Here a novel blend formulation composed by the donor-acceptor random copolymer PDPP-TT(1)-SVS(9) and polystyrene has been processed by a solution shearing technique and employed as active material in a thin film transistor. The molecular weight of the polymer binder has revealed to be fundamental for controlling the vertical phase separation and, in turn, for determining the morphological properties of the upper surface which is critical in terms of device stability. The bi-component active layer has been tested as OFET and by using a top gate as electrolyte-gated field-effect transistor (EGOFET). Our strategy based on an OSC:polymer blend processed through a solution shearing technique has demonstrated to be efficient for improving the final device performance in ambient conditions., F.L. and Q.Z. contributed equally to this work. F.L., Q.Z. and M.M.-T. thank the ERC-StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) project, FANCY CTQ2016-80030-R, the Generalitat de Catalunya (2017-SGR-918), and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Program for Centres of Excellence in R&D (SEV-2015-0496). Q.Z. acknowledges the China Scholarship Council, the National Natural Science Foundation of China (NSF) (Grant No. 11404266). Q.Z. was enrolled in the Materials Science Ph.D. Program of Universitat Autònoma de Barcelona. F.L. gratefully acknowledges the “Juan de la Cierva” program. Y.-H. K. Thanks the National Research Foundation of Korea (NRF) funded by the Ministry of Science (NRF-2018R1A2A1A05078734).

A random poly(methyl methacrylate-co-butyl acrylate-co-acrylic acid) [P(MMA-co-BA-co-AA)] was synthesized via emulsion polymerization utilizing thermally-activated persulfate radicals. The successful synthesis of high molecular weight copolymer at high monomer conversion rate was confirmed by NMR study. Various techniques were employed to characterize the structure, electrical and thermal properties of copolymer. The removal of unreacted monomers from the end product by casting technique was rationalized from the disappearance of CC FTIR characteristic peak in the cast film. The drying of the emulsion above the glass transition temperature (Tg = 24 °C) yields an amorphous film with smooth surface morphology. The suitability of the formed continuous film as a base polymer for iodide-based electrolytes in dye sensitized solar cell (DSSC) fabrication was investigated. The polymeric solid state electrolytes (PSSE) were formulated by varying the doping concentrations of sodium iodide (NaI) in fixed ratio of iodine (I2) and mixtures of ethylene carbonate: propylene carbonate (EC:PC, 1:1). The DSSC fabricated using PSSE with 15 wt.% NaI showed the highest solar-to-electrical energy conversion efficiency (η) of 3.22% under 100 mW cm−2 sunlight intensity. This implies that the physico-chemical properties of the synthesized copolymer are suitable for the development of photoelectrochemical device. Keywords: Emulsion polymerization, Random copolymer, Thermal initiator, Physico-chemical characterization, Polymer electrolytes, Dye sensitized solar cell

WOS: 000514007900001, A quinoxaline (Qx) and benzodithiophene (BDT) comprising of random copolymers, namely poly(5-(6-(5-(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b ']dithiophen-2-yl)-4-(2-ethylhexyl)thiophen-2-yl)-4,8-bis ((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b ']dithiophen-2-yl)-2,3-bis(3,4-bis(octyloxy)phenyl)quinoxaline) (PQBT), is synthesized via Stille polycondensation reaction. To investigate the effect of the pi-bridge on the electrochromic properties, 3-(2-ethylhexyl) thiophene is incorporated the between Qx and BDT moiety. The resulting random copolymer is characterized by NMR spectroscopy, gel permeation chromatography (GPC), attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). PQBT exhibits ambipolar and multichromic characteristics and is highly soluble in common solvents. Optoelectronic studies reveal two well-separated absorption bands having maxima at 500 and 532 nm with 1.83 eV optical band gap (E-g(op)). PQBT exhibits orange color in the neutral state with brown, green, and blue colors in the intermediate, oxidized, and reduced states, respectively. Subsequently, a PQBT and poly-3,4-ethylenedioxythiophene (PEDOT)-bearing prototype bilayer electrochromic device working between orange and blue colors is constructed and characterized.

A random copolymer of isobutylene (IB) and 4-vinylbenzenecyclobutylene (4-VBCB) was synthesized by cationic polymerization at &minus, 80 &deg, C using 2-chloro-2,4,4-trimethylpentane (TMPCl) as initiator. The laws of copolymerization were investigated by changing the feed quantities of 4-VBCB. The molecular weight of the copolymer decreased, and its molecular weight distribution (MWD) increased with increasing 4-VBCB content. We proposed a possible copolymerization mechanism behind the increase in the chain transfer reaction to 4-VBCB with increasing of feed quantities of 4-VBCB. The thermal properties of the copolymers were studied by solid-phase heating and crosslinking. After crosslinking, the decomposition and glass transition temperatures (Tg) of the copolymer increased, the network structure that formed did not break when reheated, and the mechanical properties remarkably improved.

The present paper describes the synthesis of novel bio-based poly(butylene 1,4-cyclohexane dicarboxylate)-containing random copolymers for sustainable and flexible packaging applications. On one side, the linear butylene moiety has been substituted by glycol subunits with alkyl pendant groups of different length. On the other side, copolymers with different cis/trans isomer ratio of cyclohexane rings have been synthesized. The prepared samples were subjected to molecular, thermal, diffractometric, and mechanical characterization. The barrier performances to O2, CO2, and N2 gases were also evaluated. The presence of side alkyl groups did not alter the thermal stability, whereas it significantly influences the formation of ordered phases that deeply affect the functional properties, mainly in terms of mechanical response and barrier performance. In particular, the final materials present higher flexibility and significantly improved barrier properties with respect to the homopolymer and most polymers widely employed for flexible packaging. The improvement due to copolymerization was more pronounced in the case of higher co-unit-containing copolymers and for the samples with cyclohexane rings in the trans conformation.

Random copolymers of poly(propylene 1,4-cyclohexanedicarboxylate) containing different amounts of neopentyl glycol sub-unit were investigated from the gas barrier point of view at the standard temperature of analysis (23 °C) with respect to the three main gases used in food packaging field: N2, O2, and CO2. The effect of temperature was also evaluated, considering two temperatures close to the Tg sample (8 and 15 °C) and two above Tg (30 and 38 °C). Barrier performances were checked after food contact simulants and in different relative humidity (RH) environments obtained with two saturated saline solutions (Standard Atmosphere, 23 °C, 85% of RH, with saturated KCl solution; Tropical Climate, 38 °C, 90% RH, with saturated KNO3 solution). The results obtained were compared to those of untreated film, which was used as a reference. The relationships between the gas transmission rate, the diffusion coefficients, the solubility, and the copolymer composition were established. The results highlighted a correlation between barrier performance and copolymer composition and the applied treatment. In particular, copolymerization did not cause a worsening of the barrier properties, whereas the different treatments differently influenced the gas barrier behavior, depending on the chemical polymer structure. After treatment, Fourier transform infrared analysis confirmed the chemical stability of these copolymers. Films were transparent, with a light yellowish color, slightly more intense after all treatments.

A series of random poly(butylene succinate)-based copolymers, (poly(butylene/triethylene succinate) (P(BSmTESn)), containing ether-oxygen atoms were successfully synthesized by melt polycondensation of succinic acid and 1,4-butanediol in the presence of triethylene glycol (TEG) (TEG content up to 40 mol %). The copolymers were characterized from the molecular, thermal, structural and mechanical point of view. Hydrolytic degradation studies were performed under physiological conditions. The biocompatibility of the samples under investigation through indirect and direct biocompatibility studies was investigated by using embryonic rat cardiac H9c2 cells. To evaluate the potential of these polymers also for controlled drug delivery systems, the diffusion profile of Dexamethasone, an anti-inflammatory drug, through nanoparticles prepared by oil-in-water miniemulsion process was investigated. Results showed that solid-state properties could be tailored nicely by simply varying copolymer composition. Crystallinity degree and hydrophobicity significantly decreased with the increase of triethylene succinate co-unit (TES) mol%. Moreover, hydrolytic degradation of PBS, depending on polymer crystallinity degree and hydrophilicity, was remarkably improved: the copolymer containing 40 mol% of triethylene succinate co-unit after 200 days lost over 22% of its initial weight. The newly developed biomaterials showed lack of cell cytotoxicity. Among them, PBS and the copolymers containing up to 20 mol% of TES co-units sustained a better cell adhesion and proliferation. In addition, such copolymers induced muscle phenotype commitment in H9c2 cells cultured onboard. Lastly, the release profile of Dexamethasone obeyed to a first order kinetic law, the copolymer richest in TES co-unit content showing the highest encapsulation capability and the fastest drug release kinetics. Anyway, PBS and the copolymers containing up to 20 mol% of TES co-unis sustained a better cell adhesion and proliferation, with the copolymers characterized by a myosin heavy chain expression, which appeared to be up to twofold increased on respect to the one of PBS homopolymer. (C) 2018 Elsevier Ltd. All rights reserved.

A series of novel random copolymers of poly(propylene 1,4-cyclohexanedicarboxylate) (PPCE) containing neopentyl glycol sub-unit (P(PCExNCEy)) were synthesized and characterized in terms of molecular and solid-state properties. In addition, biodegradability studies in compost have been conducted. The copolymers displayed a high and similar thermal stability with respect to PPCE. At room temperature, all the copolymers appeared as semicrystalline materials: the main effect of copolymerization was a lowering of crystallinity degree (Xc) and a decrease of the melting temperature compared to the parent homopolymer. In particular, Wide Angle X-Ray diffraction (WAXD) measurements indicated that P(PCExNCEy) copolymers are characterized by cocrystallization, PNCE counits cocrystallizing in PPCE crystalline phase. Final properties and biodegradation rate of the materials under study were strictly dependent on copolymer composition and Xc. As a matter of fact, the elastic modulus and the elongation at break decreased and increased, respectively, as neopentyl glycol cyclohexanedicarboxylate (NCE) unit content was increased. The presence of a rigid-amorphous phase was evidenced by means of Dynamic Mechanical Thermal Analysis (DMTA) analysis in all the samples under investigation. Lastly, the biodegradation rate of P(PCExNCEy) copolymers was found to slightly increase with the increasing of NCE molar content.

International audience; Single stage injection blow molding process, without preform storage and reheat, could be run on a standard injection molding machine, with the aim of producing short series of specific hollow parts. The polypropylene bottles are blow molded right after being injected. This implies that the preform has to remain sufficiently malleable to be blown while being viscous enough to avoid being pierced during the blow molding stage. These constraints lead to a small processing window, and so the process takes place between the melting temperature and the crystallization temperature, where the polypropylene is in its molten state but cool enough to enhance its viscosity without crystallizing. This single stage process introduces temperature gradients, high stretch rate and high cooling rate. Melt rheometry tests were performed to characterize the polymer behavior in the temperature range of the process, as well as Differential Scanning Calorimetry. A viscous Cross model is used with the thermal dependence assumed by an Arrhenius law. The process is simulated through a finite element code (POLYFLOW) in the ANSYS Workbench framework. The geometry allows an axisymmetric approach. The transient simulation is run under anisothermal conditions and viscous heating is taken into account. Sensitivity studies are carried out and reveal the influence of process parameters such as the material behavior, the blowing pressure and the initial temperature field. Thickness measurements using image analysis are performed and the simulation results are compared to the experimental ones. The simulation shows broad agreements with the experimental results. An optimization loop is run to determine the optimal initial thickness repartition. Design points are defined along the preform and the optimization modifies the thickness at these locations.

In the last decade, there has been an increased interest from the food packaging industry toward the development and application of biodegradable and biobased plastics, to contribute to the sustainable economy and to reduce the huge environmental problem afflicting the planet. In this framework, the present paper describes the synthesis of novel PBS (poly(butylene succinate))-based random copolymers with different composition containing glycol sub-units characterized by alkyl pendant groups of different length. The prepared samples were subjected to molecular, thermal, diffractometric and mechanical characterization. The barrier performances to O2, CO2 and N2 gases were also evaluated, envisioning for these new materials an application in food packaging. The presence of the side alkyl groups did not alter the thermal stability, whereas it significantly reduced the sample crystallinity degree, making these materials more flexible. The barrier properties were found to be worse than PBS; however, some of them were comparable to, or even better than, those of Low Density Polyethylene (LDPE), widely employed for flexible food packaging. The entity of variations in the final properties due to copolymerization were more modest in the case of the co-unit with short side methyl groups, which, when included in the PBS crystal lattice, causes a more modest decrement of crystallinity degree.

Poly(butylene succinate) (PBS) based random copolyesters containing thioether-linkages were synthesized by melt polycondensation, and characterized from the molecular and thermo-mechanical point of view. Permeability to O-2 and CO2 gases and biodegradation rate in compost have been also evaluated. The synthesized semicrystalline copolymers have proved to be thermally stable and characterized by PBS crystal phase. The main effect of copolymerization was a lowering in the crystallinity degree and a decrease of T-m with respect to homopolymer. The dependence of T-m on composition was described by Baur's equation. Slightly different surface hydrophilicity has been also displayed. Mechanical properties and the biodegradation rate turned out to be deeply influenced by the copolymers' composition, in particular the higher the thiodiethylene glycol mol% the higher the elongation at break and the biodegradation extent. It is worth mentioning that the synthesized copolymers displayed better barrier properties to both studied gases with respect to commercial Poly(lactic acid). (C) 2016 Elsevier Ltd. All rights reserved.

The processing of solution-based binary blends of the ferroelectric random copolymer poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and the semiconducting polymer poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) applied by spin-coating and wire-bar coating is investigated. By systematic variation of blend composition, solvent, and deposition temperature it is shown that much smoother blend films can be obtained than reported thus far. At a low PFO:P(VDF-TrFE) ratio the blend film consists of disk-shaped PFO domains embedded in a P(VDF-TrFE) matrix, while an inverted structure is obtained in case the P(VDF-TrFE) is the minority component. The microstructure of the phase separated blend films is self-affine. From this observation and from the domain size distribution it is concluded that the phase separation occurs via spinodal decomposition, irrespectively of blend ratio. This is explained by the strong incompatibility of the two polymers expressed by the binary phase diagram, as constructed from thermal analysis data. Time resolved numerical simulation of the microstructure evolution during de-mixing qualitatively shows how an elevated deposition temperature has a smoothening effect as a result of the reduction of the repulsion between the blend components. The small roughness allowed the realization of bistable rectifying diodes that switch at low voltages with a yield of 100%. This indicates that memory characteristics can be tailored from the outset while processing parameters can be adjusted according to the phase behavior of the active components. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Poly(butylene succinate/diglycolate) random copolymers (P(BSxBDGy)) of various compositions were synthesized and characterized from the molecular, thermal, structural and mechanical point of view. All the polymers showed a good thermal stability and at room temperature they appeared as semicrystalline materials. The main effect of copolymerization was a lowering in the crystallinity and a decrease of T-m respect to homopolymers. The dependence of T-m on composition for copolymers with high butylene succinate unit content was well described by Baur's equation. WAXD measurements indicated that two different crystalline phases are present, depending on composition: copolymers with high BS unit content are characterized by PBS crystal phase, whereas those rich in BDG co-units crystallized in PBDG lattice. Amorphous samples showed a monotonic increment of; as the content of BDG units is increased and this can be explained on the basis of interchain interactions, due to the high electronegativity of ether-oxygen atoms. A Fox-type equation was found to fit the T-g data of completely amorphous samples, permitting the extrapolation of pure PBS T-g value for the completely amorphous polymer. (C) 2012 Elsevier Ltd. All rights reserved.

Real-time development of the mesomorphic structure in random propene-ethylene copolymers has beenmonitored during fast cooling from the melt by coupling an effective quenching device with a state-of the-art detector at a synchrotron radiation facility. Even when the whole structuring process lasts onlyfew tenths of a second, it has been possible to precisely follow the progress of the phase transition.This has enabled us to appreciate that the kinetics of the mesophase development is affected to a lesserextent that of the monoclinic -form by randomly distributed ethylene constitutional defects.

This study describes a simple yet efficient approach for the preparation of an ionic gel that is also elastomeric in its solid-state bulk form. A series of poly(2-(diethylamino)ethyl methacrylate- co -lauryl methacrylate) P(DMAEMA- co -LMA) copolymers were synthesized first by radical polymerization. Quaternization of the PDMAEMA component in tetrahydrofuran enables the formation of supramolecular network, giving rise to an ion gel. An elastomer with an elongation at break of over 600% was obtained from the gel. The elastomer, connected by supramolecular ionic cross-links, is solvoplastic in certain solvents. The simple yet efficient approach of the formation of ion-gel and the dried elastomer allows fast preparation of both gel-like and solid-state elastic materials for various applications where recyclability is required.

cited By 0; International audience; The viscoelastic behavior of poly(methyl methacrylate) (PMMA) homopolymer and poly(methyl methacrylate-co-methyl acrylate) random copolymers was characterized by dynamic mechanical analysis and nanoindentation. Differential scanning calorimetric results showed only one glass transition, indicating the random distribution of comonomers in the copolymers. The a relaxation temperature (Tα) and activation energy (Hα) decreased with increasing content of methyl acrylate monomers (CMA%). The β relaxation temperature (Tβ) also decreased whereas the activation energy (Hβ) showed only small variations compared with Hα. Moreover, the indention displacement and creep compliance strongly depended on CMA%. Two creep stages were found in the creep compliance curves. Copyright © Taylor and Francis Group, LLC.

Adsorption of a symmetric (AB) random copolymer (RC) onto a symmetric (ab) random heterogeneous surface (RS) is studied in the annealed approximation by using a two-dimensional partially directed walk model of the polymer. We show that in the symmetric case, the expected a posteriori compositions of the RC and the RS have correct values (corresponding to their a priori probabilities) and do not change with the temperature, whereas second moments of monomers and sites distributions in the RC and RS change. This indicates that monomers and sites do not interconvert but only rearrange in order to provide better matching between them and, as a result, a stronger adsorption of the RC on the RS. However, any violation of the system symmetry shifts equilibrium towards the major component and/or more favorable contacts and leads to interconversion of monomers and sites., Comment: 15 pages, 7 figures

The influence of both temperature and time on the solid–solid transformation from tetragonal Form II mesophase to trigonal Form I crystals in isotactic poly(butene-1) and its random copolymers with ethylene has been evaluated. The polymers were isothermally crystallized and then annealed at temperatures ranging from −30 to +30 °C for various times, up to 24 h. Incorporation of ethylene co-units into isotactic poly(butene-1) not only leads to a faster solid–solid transformation rate, as already discussed in the literature, but it also affects the temperature of maximum transformation rate. For all the analyzed compositions, at the initial stage of the process, a maximum rate is observed upon annealing around −20 °C, whereas when the transition proceeds to a later stage, it becomes much faster around +20 °C. The occurrence of two maxima in the transformation-temperature profile has been correlated with a nucleation and growth mechanism for the Form II to Form I transition. The influence of ethylene co-units on the transformation rate has been rationalized taking into account the varied composition of the rigid amorphous portions at the lamellar basal planes of the crystals, which confirms the hypothesis of a connection between crystal lamellae rearrangements and the amorphous-crystal boundaries.

Poly(N-isopropylacrylamide) (PNIPAM) and random copolymers of Poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (PNIPAM-HEMA), poly(N-isopropylacrylamide-co-acrylamide) (PNIPAM-AAm), and poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) (PNIPAM-DMAA) with various volume fractions γ of NIPAM were synthesized by radical polymerization. The phase behavior of the polymers in water was investigated by means of optical transmittance and dynamic light scattering. With decreasing γ, the cloud point temperature Tcp for PNIPAM-HEMA decreased whereas the Tcp for both PNIPAM-AAm and PNIPAM-DMAA increased. Increase of hydrodynamic radius around Tcp, which resulted from the aggregation of the globules of each polymer, was observed from dynamic light scattering. The relationships between the reciprocal of Tcp of the polymer solutions and 1-γ were linear for the three copolymers in the experimental range of 0.65

A half-metallocene iron iodide complex [Fe(Cp)I(CO)2] induced living radical polymerization of methyl acrylate (MA) in conjunction with an iodide initiator [(CH3)2C(CO2Et)I, 1] and Al(Oi-Pr)3 to give polymers of controlled molecular weights and narrow molecular weight distributions (MWDs) (Mw/Mn < 1.2). With the use of chloride and bromide initiators, the MWDs were broader, whereas the molecular weights were similarly controlled. Other acrylates such as n-butyl acrylate (nBA) and tert-butyl acrylate (tBA) can be polymerized with 1/Fe(Cp)I(CO)2 in the presence of Ti(Oi-Pr)4 and Al(Oi-Pr)3, respectively, to give living polymers. The 1/Fe(Cp)I(CO)2 initiating system is applicable for the synthesis of block and random copolymers of acrylates (MA, nBA, and tBA) and styrene of controlled molecular weights and narrow MWDs (Mw/Mn = 1.2–1.3). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2033–2043, 2002

A new class of biodegradable and biocompatible poly(butylene 1,4-cyclohexanedicarboxylate) based random copolymers are proposed for biomedical applications. The introduction of ether–oxygen containing BDG sequences along the PBCE macromolecular chain is expected to remarkably improve chain flexibility and surface hydrophilicity due to the presence of highly electronegative oxygen atoms. P(BCExBDGy) copolymers were synthesized by polycondensation. The homopolymer PBCE and three copolymers, namely (P(BCE70BDG30), P(BCE55BDG45) and P(BCE40BDG60)) were characterized from the molecular, thermal, structural and mechanical point of view. Hydrolytic degradation studies in the presence and absence of hog-pancreas lipase were performed under physiological conditions. To evaluate the diffusion profile of small molecules through the polymer matrix, the release behaviour of fluorescein isothiocyanate (FITC) was investigated. For biocompatibility studies, cell adhesion and proliferation of murine fibroblast (L929) and endocrine pancreatic (INS-1) cells were performed on each polymeric film. Results showed that solid-state properties can be tailored by simply varying copolymers' composition. Crystallinity degree and hydrophobicity significantly decreased with the increase of BDG co-unit mol%. Moreover, mechanical properties and biodegradability of PBCE, both depending on crystallinity degree, were remarkably improved: P(BCE40BDG60) showed an elastomeric behaviour with eb over 600% and, as regard to biodegradability, after 98 days it lost over 60% of its initial weight if incubated in the presence of the pancreatic lipase. Lastly, the newly developed biomaterials resulted not cytotoxic with both types of cells and could be properly tailored for biomedical applications varying the content of BDG co-unit mol%.

A series of novel random copolymers of poly(butylene 1,4-cyclohexanedicarboxylate) (PBCE) containing triethylene glycol sub-unit (P(BCEmTECEn)) were synthesized and characterized in terms of molecular and solid-state properties, among these barrier properties to different gases (oxygen and carbon dioxide). In addition, biodegradability studies both in soil and in compost and ecotoxicological analysis, by means of the Lepidium sativum test, have been conducted. The copolymers displayed a high and similar thermal stability with respect to PBCE. At room temperature, all the copolymers appeared as semicrystalline materials: the main effect of copolymerization was a lowering of crystallinity degree (χc) and a decrease of the melting temperature compared to the parent homopolymer. The Baur's equation well described the Tm-composition data. Final properties and biodegradation rate of the materials under study were strictly dependent on copolymer composition and χc. As a matter of fact, hydrophilicity regularly increased with the increasing of TECE mol%, due to the PEG-like portion. The elastic modulus and the elongation to break decreased and increased, respectively, as TECE unit content was increased. As to the barrier properties, the selectivity ratios for the examined samples increased with the increasing of TECE mol%, confirming the correlation between the permeability and the chemical composition. The copolymers with lower TECE unit content (up to 30 mol%) showed improved barrier properties with respect to polylactide films tested under the same conditions. Lastly, the biodegradation rate of P(BCEmTECEn) copolymers increased with the increasing of TECE mol%, while PBCE remained almost undegraded in the explored conditions.

A series of cyclopentadiene (CPD)-based polymers and copolymers were synthesized by a controlled cationic polymerization of CPD. End-functionalized poly-(CPD) was synthesized with the HCl adducts [initiator = CH 3 CH(OCH 2 CH 2 X)Cl; X = Cl (2a), acetate (2b), or methacrylate] of vinyl ethers carrying pendant functional substituents X in conjunction with SnCl 4 (Lewis acid as a catalyst) and n-Bu 4 NCl (as an additive) in dichloromethane at -78 °C. The system led to the controlled cationic polymerizations of CPD to give controlled α-end-functionalized poly(CPD)s with almost quantitative attachment of the functional groups (F n ∼ 1). With the 2a or 2b/SnCl 4 /n-Bu 4 NCl initiating systems, diblock copolymers of 2-chloroethyl vinyl ether (CEVE) and 2-acetoxyethyl vinyl ether with CPD were also synthesized by the sequential polymerization of CPD and these vinyl ethers. An ABA-type triblock copolymer of CPD (A) and CEVE (B) was also prepared with a bifunctional initiator. The copolymerization of CPD and CEVE with 2a/SnCl 4 /n-Bu 4 NCl afforded random copolymers with controlled molecular weights and narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight = 1.3-1.4).

Poly(butylene cyclohexanedicarboxylate/diglycolate) random copolymers (P(BCEmBDGn)) of various compositions were synthesized and characterized from the molecular, thermal, structural, and mechanical point of view. Barrier properties to different gases (oxygen and carbon dioxide) were also evaluated. All the polymers showed good thermal stability and appeared as semicrystalline materials at room temperature. The main effect of copolymerization was a lowering in the crystallinity and a decrease of Tm with respect to homopolymers. The dependence of Tm on composition for copolymers with high butylene cyclohexanedicarboxylate unit content was well described by Baur's equation. X-ray diffraction (XRD) measurements indicated that two different crystalline phases are present, depending on composition: copolymers with high BCE unit content were characterized by PBCE crystal phase, whereas those rich in BDG counits crystallized in PBDG lattice. The samples displayed different surface hydrophilicity: the water contact angle regularly decreased with the increasing mol % of BDG. The mechanical properties were found strictly related to crystallinity degree (?c); the copolymers containing 60-75 mol % of BDG showed the lowest elastic modulus and the highest elongation at break. Lastly, the chemical composition of the copolymer strongly influenced permeability to CO2 and O2. Moreover, the selectivity ratios for the examined samples increased with the increasing of BDG mol %, confirming the existence of a correlation between the permeability and the chemical composition. Almost all copolymers showed improved barrier properties with respect to polylactide films tested under the same conditions. © 2013 American Chemical Society.

Magnetoresponsive polymer-based fibrous nanocomposites belonging to the broad category of stimuli-responsive materials, is a relatively new class of “soft” composite materials, consisting of magnetic nanoparticles embedded within a polymeric fibrous matrix. The presence of an externally applied magnetic field influences the properties of these materials rendering them useful in numerous technological and biomedical applications including sensing, magnetic separation, catalysis and magnetic drug delivery. This study deals with the fabrication and characterization of magnetoresponsive nanocomposite fibrous membranes consisting of methacrylic random copolymers based on methyl methacrylate (MMA) and 2-(acetoacetoxy)ethyl methacrylate (AEMA) (MMA-co-AEMA) and oleic acid-coated magnetite (OA·Fe3O4) nanoparticles. The AEMA moieties containingβ-ketoester side-chain functionalities were introduced for the first time in this type of materials, because of their inherent ability to bind effectively onto inorganic surfaces providing an improved stabilization. For membrane fabrication the electrospinning technique was employed and a series of nanocomposite membranes was prepared in which the polymer content was kept constant and only the inorganic (OA·Fe3O4) content varied. Further to the characterization of these materials in regards to their morphology, composition and thermal properties, assessment of their magnetic characteristics disclosed tunable superparamagnetic behaviour at ambient temperature.

The random architecture of a commercial copolymer of poly(DL-lactic acid) and poly(ε-caprolactone), poly(DL-lactide-co-caprolactone), has been characterized by chemical structure analysis from hydrogen-1 nuclear magnetic resonance results. Moreover, spherical nanodomains have been detected in the thin films of this copolymer obtained after solvent evaporation. These nanodomains studied by atomic force microscopy and transmission elecron microscopy grow progressively under annealing until they collapse and form a homogenous disordered structure. This is the first time that the nanostructure of random poly(DL-lactic acid)/poly-(ε-caprolactone) copolymers is revealed, representing one of few experimental evidences on the possible nanostructuration of random copolymers., This project has been supported by Projects MAT2010-21494-C03-03 and MAT2008-00619/MAT of the Spanish Ministry for Science and Innovation (MICINN). LP acknowledges the support of the Juan de la Cierva grant from MICINN (MICINN-JDC)

A novel random copolymer based on donor⁻acceptor type polymers containing benzodithiophene and dithienosilole as donors and benzothiazole and diketopyrrolopyrrole as acceptors was designed and synthesized by Stille copolymerization, and their optical, electrochemical, charge transport, and photovoltaic properties were investigated. This copolymer with high molecular weight exhibited broad and strong absorption covering the spectra range from 500 to 800 nm with absorption maxima at around 750 nm, which would be very conducive to obtaining large short-circuits current densities. Unlike the general approach using single solvent to prepare the active layer film, mixed solvents were introduced to change the film feature and improve the morphology of the active layer, which lead to a significant improvement of the power conversion efficiency. These results indicate that constructing random copolymer with multiple donor and acceptor monomers and choosing proper mixed solvents to change the characteristics of the film is a very promising way for manufacturing organic solar cells with large current density and high power conversion efficiency.

Cancer is the leading cause of death worldwide. Nanomaterials and nanotechnologies could provide potential solutions. In this research, a novel biodegradable poly(lactide-co-glycolide)-d-a-tocopheryl polyethylene glycol 1000 succinate (PLGA-TPGS) random copolymer was synthesized from lactide, glycolide and d-a-tocopheryl polyethylene glycol 1000 succinate (TPGS) by ring-opening polymerization using stannous octoate as catalyst. The obtained random copolymers were characterized by 1H NMR, FTIR, GPC and TGA. The docetaxel-loaded nanoparticles made of PLGA-TPGS copolymer were prepared by a modified solvent extraction/evaporation method. The nanoparticles were then characterized by various state-of-the-art techniques. The results revealed that the size of PLGA-TPGS nanoparticles was around 250 nm. The docetaxel-loaded PLGA-TPGS nanoparticles could achieve much faster drug release in comparison with PLGA nanoparticles. In vitro cellular uptakes of such nanoparticles were investigated by CLSM, demonstrating the fluorescence PLGA-TPGS nanoparticles could be internalized by human cervix carcinoma cells (HeLa). The results also indicated that PLGA-TPGS-based nanoparticles were biocompatible, and the docetaxel-loaded PLGA-TPGS nanoparticles had significant cytotoxicity against Hela cells. The cytotoxicity against HeLa cells for PLGA-TPGS nanoparticles was in time- and concentration-dependent manner. In conclusion, PLGA-TPGS random copolymer could be acted as a novel and promising biocompatible polymeric matrix material applicable to nanoparticle-based drug delivery system for cancer chemotherapy.