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We performed dynamic Monte Carlo simulations of random copolymers containing variable sliding mobility of non-crystallizable comonomer sequences (reflecting their relative sizes) in the crystalline monomer regions. Upon raising strains, we observed that the comononer sliding mobility does not affect the strain evolution curves of crystallinity. However, in the middle temperature region, the low mobility causes a delay of switching from the intra-molecular to the inter-molecular modes of crystal nucleation in the copolymers holding low fractions of comonomers. We attributed the effect to the difficulty of comonomers to be excluded from the nucleating domains that are limited by sequence segregation in the oriented amorphous segments. The implication of this effect to the efficiency of crystal nucleation upon cyclic loading has been discussed. [ABSTRACT FROM AUTHOR]

Starting from an initial sample of butene-1/ethylene copolymer with stable form I', we examined the nucleation of different crystalline polymorphs (here metastable form II and stable form I') at different isothermal crystallization temperatures after being melted at different melt temperature ( T ). When T was just above the melting temperature ( T ) of the crystallites, self-seeding took place. There, residue crystallites served as nuclei leading to the crystallization of the same crystalline phase. When T was a few degrees above the T , self-seeding was disabled due to complete melting of the initial crystals. Upon crystallization, the selection of the different polymorphs in this random copolymer was found to depend on an interplay between the domain size of segregated long crystallizable sequences and the size and energy barrier of the critical nucleus of the respective crystalline forms. Our results provide a clear understanding of the polymorphs selection during crystallization of a random copolymer as well as homo-polymers under confinement. [ABSTRACT FROM AUTHOR]

ABSTRACT For the purpose of developing poly(3-hexylthiophene) (P3HT) based copolymers with deep-lying highest occupied molecular orbital (HOMO) levels for polymer solar cells with high open-circuit voltage ( Voc), we report a combined approach of random incorporation of 3-cyanothiophene (CNT) and 3-(2-ethylhexyl)thiophene (EHT) units into the P3HT backbone. This strategy is designed to overcome CNT content limitations in recently reported P3HT-CNT copolymers, where incorporation of more than 15% of CNT into the polymer backbone leads to impaired polymer solubility and raises the HOMO level. This new approach allows incorporation of a larger CNT content, reaching even lower-lying HOMO levels. Importantly, a very low HOMO level of −5.78 eV was obtained, representing one of the lowest HOMO values for exclusively thiophene-based polymers. Lower HOMO levels result in higher Voc and higher power conversion efficiencies (PCE) compared to the previously reported P3HT-CNT copolymers containing only 3-hexylthiophene and CNT units. As a result, solar cells based on P3HT-CNT-EHT(15:15), which contains 70% of P3HT, 15% of CNT and 15% of EHT, yield a Voc of 0.83 V in blends with PC61BM while preserving high fill factor (FF) and high short-circuit current density ( Jsc), resulting in 3.6% PCE. Additionally, we explored the effect of polymer number-average molecular weight ( Mn) on the optoelectronic properties and solar cell performance for the example of P3HT-CNT-EHT(15:15). The organic photovoltaic (OPV) performance improves with polymer Mn increasing from 3.4 to 6.7 to 9.6 kDa and then it declines as Mn further increases to 9.9 and to 16.2 kDa. The molecular weight study highlights the importance of not only the solar cell optimization, but also the significance of individual polymer properties optimization, in order to fully explore the potential of any given polymer in OPVs. The broader ramification of this study lies in potential application of these high band gap copolymers with low-lying HOMO level in the development of ternary blend photovoltaics as well as tandem OPV. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1526-1536 [ABSTRACT FROM AUTHOR]

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Charge-containing polymeric materials have been widely studied for a range of applications. The fundamental relationships between the charge species, charge density, and the microscale morphology of charge-containing polymers are critical for defining the application in which they may be used. In this work, a series of thermoplastic poly(arylene ether sulfone) (PAES) copolymers with controllable sulfobetaine charge contents (0–100 mol%) and high molecular weights (Mw ∼ 65 kDa) were prepared. All the zwitterionic PAESs synthesized showed thermal stability up to 250 °C. DSC and tensile tests showed a decreased T g and mechanical strength with the incorporation of increasing charge density, which suggests a plasticization effect by the charged group. Electron microscopy and X-ray scattering data confirmed the absence of microphase separation in the ion-containing random copolymer system, which corroborated with the observation of a single T g for all zwitterionic copolymers studied. Furthermore, the relative hydrophilicity of the samples was evaluated by water uptake measurements, which revealed that the water uptake of the zwitterionic PAESs can reach up to 64% for the 72 mol% zwitterion copolymer while the free-standing film in the wet state still maintains a Young's modulus of 185 MPa. The thermoplastic charge-containing copolymers in this work demonstrated potential for applications such as coatings or water purification membranes, in which balancing hydrophilicity, processibility, and thermomechanical performance are important. [Display omitted] • A series of zwitterionic polysulfone copolymers with sulfobetaine content (0–100%) and high M w ∼ 65 kDa was synthesized. • The STEM/SAXS/WAXS data confirm the absence of ionic aggregates and support the single-T g observation for the copolymers. • The T g and Young's modulus decreased with an increase in charge content suggesting a plasticization effect by the zwitterion. • Water uptake of the zwitterionic polysulfones increased up to 64 wt%. • Freestanding films in the wet state exhibited a Young's modulus of up to 183.4 ± 86.3 MPa. [ABSTRACT FROM AUTHOR]

Double-cable conjugated polymers with pendent electron acceptors, including fullerene, rylene diimides, and nonfused acceptors, have been developed for application in single-component organic solar cells (SCOSCs) with efficiencies approaching 10%. In this work, Y-series electron acceptors have been firstly incorporated into double-cable polymers in order to further improve the efficiencies of SCOSCs. A highly crystalline Y-series acceptor based on quinoxaline core and the random copolymerized strategy are used to optimize the ambipolar charge transport and the nanophase separation of the double-cable polymers. As a result, an efficiency of 13.02% is obtained in the random double-cable polymer, representing the highest performance in SCOSCs, while the regular double-cable polymer only provides a low efficiency of 2.75%. The significantly enhanced efficiencies are attributed to higher charge carrier mobilities, better ordering conjugated backbones and Y-series acceptors in random double-cable polymers., (© 2023 Wiley-VCH GmbH.)

In this paper we study a model describing a copolymer in a micro-emulsion. The copolymer consists of a random concatenation of hydrophobic and hydrophilic monomers, the micro-emulsion consists of large blocks of oil and water arranged in a percolation-type fashion. The interaction Hamiltonian assigns energy -α to hydrophobic monomers in oil and energy -β to hydrophilic monomers in water, where α,β are parameters that without loss of generality are taken to lie in the cone {(α,β) ∈ R2: α ≥ |β|}. Depending on the values of these parameters, the copolymer either stays close to the oilwater interface (localization) or wanders off into the oil and/or the water (delocalization). Based on an assumption about the strict concavity of the free energy of a copolymer near a linear interface, we derive a variational formula for the quenched free energy per monomer that is column-based, i.e., captures what the copolymer does in columns of different type. We subsequently transform this into a variational formula that is slope-based, i.e., captures what the polymer does as it travels at different slopes, and we use the latter to identify the phase diagram in the (α,β)-cone. There are two regimes: supercritical (the oil blocks percolate) and subcritical (the oil blocks do not percolate). The supercritical and the subcritical phase diagram each have two localized phases and two delocalized phases, separated by four critical curves meeting at a quadruple critical point. The different phases correspond to the different ways in which the polymer moves through the micro-emulsion. The analysis of the phase diagram is based on three hypotheses about the possible frequencies at which the oil blocks and the water blocks can be visited. We show that these three hypotheses are plausible, but do not provide a proof. [ABSTRACT FROM AUTHOR]

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 absorptionmaxima 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. [ABSTRACT FROM AUTHOR]

The opto-electrical, charge transport and photovoltaic properties of the highly efficient large band gap polymer, P(BDT-TDPPDT), containing electron rich 4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b']dithiophene (BDT) and a weak electron accepting 2,5-dioctyl-4,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (TDPPDT) units were modulated by the incorporation of a relatively strong electron deficient thieno[3,4-b]thiophene (TT) unit on its backbone. A new random copolymer (RP2) was prepared by polymerizing the BDT derivative with TDPPDT and TT derivatives at a 2:1:1 ratio. The estimated optical band gap ( E g ) and highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO) energy levels of RP2 were 1.70 eV and −5.30 eV/−3.60 eV, respectively. The determined hole mobility of RP2 was 4.0 × 10 −4 cm 2 V −1 s −1 . The polymer solar cells (PSCs) prepared with a simple device configuration of ITO/PEDOT:PSS/RP2:PC 70 BM/Al offered a maximum power conversion efficiency ( PCE ) of 5.12% with an open circuit voltage ( V oc ) of 0.75 V, a current density ( J sc ) of 12.99 mA/cm 2 , and a fill factor ( FF ) of 53%. The incorporation of a TT unit on the P(BDT-TDDPT) backbone was found to reduce the band gap by 0.41 eV and increase slightly the hole mobility of the resulting copolymer, RP2. Consequently, the PSC prepared from RP2 showed the enhanced photocurrent compared with that of the PSC prepared from P(BDT-TDPPDT). [ABSTRACT FROM AUTHOR]

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 α 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. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) are a family of polyesters synthesized by bacteria. Similarly to the genome, transcriptome, and proteome (the entire array of nucleic acids and proteins present in a cell or population of cells at a given time), the PHA spectrum exhibits diverse and dynamic modifications – the ‘PHAome’ – reflecting not only by the diversity of monomers, homopolymers, random and block copolymers, functional and graft polymers, molecular weights, and combinations of the above, but also the ranges of PHAs with various molecular weights and monomer ratios that are present at a particular timepoint in a bacterial cell. Echoing the Materials Genome Initiative (MGI) launched in 2011 to develop an infrastructure to accelerate advanced materials discovery and deployment, understanding the PHAome and ensuring an ample supply of PHAs based on it will promote the discovery of new properties and applications of this family of advanced materials. [ABSTRACT FROM AUTHOR]

Crystalline anatase TiO 2 with nanosponge-like mesoporous morphologies was solvothermally synthesized following the recently reported route using random copolymer (4-vinylphenol and methyl methacrylate) as structure-directing agent. In particular, the synthesis conditions were varied over a wide range of synthesis gel compositions. Crystallinity of the titania products was checked with X-ray powder diffraction. Mesopore diameters, pore volume and specific surface area were analyzed using nitrogen adsorption. The result provided proper synthesis domains for highly mesoporous titania materials. The mesoporous materials were evaluated as supports for catalytic Pt nanoparticles to apply for alcohol-to-aldehyde partial oxidation reactions. [ABSTRACT FROM AUTHOR]

An amphiphilic random copolymer was synthesized and applied as a surfactant in seed emulsion polymerization. The composition and structure of the copolymer were confirmed by Fourier transforms infrared spectroscopy (FTIR), 'H nuclear magnetic resonance spectroscopy (¹H NMR), gel permeation chromatography (GPC) and differentia! scanning calorimetry (DSC). The effect of the copolymer content on the properties of latexes and their sizing properties was discussed. The average size, size distribution and stability of latexes were measured by quasi-elastic light scattering. The results suggest that the copolymer was a random copolymer, and displayed surface-active properties in water. The copolymer content affected strongly the properties of latex and its sizing performance. Monodisperse and nano-sized latex particles were obtained in the presence of 10.5% copolymer. The thermal characteristics of latex films could be regulated by controlling the content of the copolymer. Adding an appropriate amount of the copolymer could reduce the surface tension of the latexes and promote their adsorption on the paper surface. Latex-treated paper showed a better water resistance and higher surface strength. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In recent years, the dewetting behavior of block copolymer films has been studied a lot, but that of random copolymer films was rarely studied. In this study, effects of film thickness and solvent vapor annealing duration (0 s-24 h) on the dewetting behavior of the spin-coated poly(styrene-co-acrylonitrile) (SAN) random copolymer films were mainly investigated by atomic force microscopy and contact angle method for the first time. The film thicknesses of the SAN films prepared at different concentrations were characterized by X-ray reflectometry to be 6-34 nm. With the annealing of acetone vapor, the SAN films first appear holes and then rupture into droplets which fuse and break periodically. The periodic evolutions of the droplets are due to the preferred affinity of acetone molecules with the AN segments and the change of surface energy. This phenomenon is different from the single evolutions in the spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) block copolymer films. This illustrates the interactions between AN segments and the substrate are stronger than those between PMMA segments and the substrate in the spin-coated films., (© 2022 Wiley-VCH GmbH.)

Background: This study evaluated the biocompatibilities of random and putative block poly(3-hydroxybutyrate-co-3-hydroxyvalerate)s (PHBVs) produced by a metabolic reaction-based system. The produced PHBVs were fractionated, and the copolymer sequence distributions were analyzed using ¹H and 13C NMR spectroscopy. The thermal properties were analyzed using differential scanning calorimetry (DSC). Mechanical tests were conducted using a universal testing machine. The in vitro cytotoxicities of films composed of random PHBVs and putative block PHBVs were investigated against three types of mammalian cells. The surfaces of the copolymer films and the morphologies of the cells were qualitatively monitored using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Results: Films composed of poly(3-hydroxybutyrate) (PHB), random PHBVs, putative block PHBVs, polystyrene and polyvinylchloride were prepared and characterized. The diad and triad sequence distributions indicated that the PHBVs produced via the fed-batch cultivation using two different feed systems resulted in two types of copolymers: random PHBVs and putative block PHBVs. The monomer compositions and sequence distributions strongly affected the thermal and mechanical properties. The mechanical integrity and characteristics of the film surfaces changed with the HV content. Notably, the random PHBVs possessed different mechanical properties than the putative block PHBVs. The biocompatibilities of these films were evaluated in vitro against three types of mammalian cells: L292 mouse connective tissue, human dermal fibroblast and Saos-2 human osteosarcoma cells. None of the PHBV films exhibited cytotoxic responses to the three types of mammalian cells. Erosion of the PHA film surfaces was observed by scanning electron microscopy and atomic force microscopy. The production of transforming growth factor-β-1 and interleukin-8 was also examined with regards to the usefulness of PHB and PHBV as biomaterials for regenerative tissue. The production of IL-8, which is induced by PHB and PHBVs, may be used to improve and enhance the wound-healing process because of deficiencies of IL-8 in the wound area, particularly in problematic wounds. Conclusion: Taken together, the results support the use of PHB and the random and putative block PHBVs produced in this study as potential biomaterials in tissue engineering applications for connective tissue, bone and dermal fibroblast reconstruction. [ABSTRACT FROM AUTHOR]

A series of 3-substituted polythiophene copolymers having different side chain arrangements of hexyl and hexyloxy groups has been synthesized via the Grignard metathesis ( GRIM) method and systematically studied. Despite differences in monomer reactivity ratios for the nickel-catalyzed chain transfer polymerization, random sequences of hexyl- and hexyloxy-substituted polythiophenes with different monomer compositions and adjustable band-gap energies can be synthesized according to their respective comonomer feed ratio, as evidenced from NMR, UV, electrochemical measurements, and computational calculations. Structural characterization from X-ray diffraction measurements reveals that the flexible hexyloxy side chains of the monomer significantly affect the crystallinity and molecular packing of the random copolymers. This study shows potential for synthesizing random copolymers with different monomer reactivities via the GRIM method for future optoelectronic applications. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Four novel random poly(3 ‐ hexylthiophene) copolymers containing 5–20% of 3 ‐ cyanothiophene are synthesized by Stille polycondensation; and their electrochemical, optical, charge transport, and photovoltaic properties are investigated. All polymers show high efficiencies and high open ‐ circuit voltages (Voc) up to 0.81 V with a PC61BM acceptor in organic solar cells. [ABSTRACT FROM AUTHOR]

Dioxomolybdenum complexes were examined as catalysts for the copolymerization of ε-caprolactone (ε-CL) and l-lactide ( l-LA). The bis-[(5-OMe)salicylaldehydato]dioxomolybdenum complex completed the copolymerization after 20 h at 110 °C with 0.05 mol% of the catalyst to produce a copolymer in high yield. The microstructure of the copolymer was analyzed using H and C NMR spectroscopy and was determined to have a random structure. The r values calculated from the heterodiad analysis of the H NMR data were r = 0.91 and r = 0.93, and the L values calculated from the triad analysis of the C NMR data were L = 1.58 and L = 1.81. Other dioxomolybdenum complexes, such as cis-α MoO[(3-MeO)DiMeSaltn], MoO(acac) and (NH)[MoO] exhibited comparable or slightly lower reactivity for the copolymerization. Consecutive polymerization of ε-CL followed by l-LA afforded a block copolymer without trans-esterification. [ABSTRACT FROM AUTHOR]

Five coarse-grained models were built for amphiphilic random copolymers. The self-assembly of amphiphilic random copolymers in selective solvent was investigated via dissipative particle dynamics simulations. The simulation results showed that the content of hydrophilic particles and the repulsive parameter between solvent and copolymer particles were two key factors of the vesicle formation. We report herein on how to control the self-assembled morphology evolution. The two mechanisms of vesicle formation from amphiphilic random copolymers are found through investigating the dynamic processes of vesicle formation, which is in accordance with the experiment and simulation results of amphiphilic block copolymer reported in the literature. [ABSTRACT FROM PUBLISHER]

Copolymers of 1,3-butadiene and p-methylstyrene ( p-MS) were synthesized via anionic polymerization. A benzophenone-potassium complex was added to tune the reactivity ratio of the two monomers, leading to random and gradient composition along the copolymer chain. The overall composition and microstructure could be controlled and well characterized by GPC and 1H-NMR. The p-MS was distributed from gradient to random with increasing the content of the benzophenone-potassium complex, and the 1,2-microstructure in the polybutadiene sequence increased at the same time. The hydrogenation of the copolymer of 1,3-butadiene and p-MS resulted in the corresponding saturated copolymer with welldefined structure and narrow molecular weight distribution. [ABSTRACT FROM AUTHOR]

Abstract: In addition to preparing two indolocarbazole-based random copolymers (named as r-PICTBT1 and r-PICTBT2), this work investigated their feasibility for bulk heterojunction polymer solar cells (PSCs). These copolymers consisted of commercially available 3,9-dibromo-5,11-dioctyl-5,11-dihydroindole[3,2-b]carbazole, 2,5-bis(trimethylstannyl) thiophene and dibromobenzo[c][1,2,5]thiadiazole by varying the feed in ratios via Stille cross-coupling reactions. The photophysical and electrochemical properties of the resulting copolymers could be fine-modulated easily by adjusting the feed ratios of monomers. Both copolymers in the thin film state exhibited two obvious peaks and a vibronic shoulder in the absorption spectra. Electrochemical experiments indicated that the highest occupied molecular orbital energy levels were −4.95, −5.00eV; meanwhile, the lowest unoccupied molecular orbital energy levels were −3.38, −3.54eV for r-PICTBT1 and r-PICTBT2, respectively. Bulk heterojunction PSCs composed of an electron-donor copolymer blended with an electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) at a weight ratio of 1:1 or 1:3 were investigated. Moreover, the r-PICTBT2/PC71BM-based (w/w=1:1) PSC performed the best with an open-circuit voltage of 0.54V, short-circuit current of 6.83mA/cm2, fill factor of 0.44, and power conversion efficiency of 1.63%. [Copyright &y& Elsevier]

4-(4′-Cyanobiphenyloxy)butyl methacrylate, MA(4OCB), was copolymerized with 8-(4′-hexyloxybiphenyloxy)octyl methacrylate, MA(8O6RB), or butyl methacrylate, MA(Bu), by atom transfer radical polymerization. Phase transition behaviors and liquid crystalline properties of the random copolymers with small polydispersity were compared with those of respective homopolymers. The thermal analysis suggested that both biphenyl mesogens in the p[MA(4OCB)-co-(8O6RB)] random copolymers were oriented together rather than segregated. In the case of the p[MA(4OCB)-co-MA(Bu)] random copolymers, the butyl side-chains worked to diminish liquid crystallinity by disturbing orientation of the biphenyl mesogen due to thermal fluctuation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pseudomonas putida KT2442 as a platform for polyhydroxyalkanoates production. [•] Random P(3HB-co-3HHx) copolymer with adjustable monomer compositions were produced. [•] Random P(3HHx-co-3HD) copolymer with adjustable monomer compositions were produced. [•] Block copolymer P3HHx-b-P(3HD-co-3HDD) was biosynthesized. [•] Structure diversification provides additional diverse properties. [ABSTRACT FROM AUTHOR]

ABSTRACT We develop a theoretical model of cooperative hydration to clarify the molecular origin of the observed nonlinear depression of the lower critical solution temperature (LCST) in the aqueous solutions of thermosensitive random copolymers and find the monomer composition at which LCST shows a minimum. Phase diagrams of poly( N-isopropylacrylamide- co- N, N-diethylacrylamide) copolymer solutions are theoretically derived on the basis of the theory of cooperative hydration by introducing the microscopic structure parameter η which characterizes the distribution of the monomer sequences along the chains. We compared them with the experimental data of LCST of random copolymers with various monomer compositions and also of the diblock copolymers with equimolar monomer composition. The transition temperature shifts to lower than those of homopolymer counterparts when the monomer sequence of the chains has an alternative tendency. On the contrary, for the blocky polymers such as diblock copolymers, the transition temperature remains almost the same as those of the homopolymers. Thus, the nonlinear effect in phase separation appears when the average block length of the copolymers is shorter than the average sequence length of the cooperative hydration. The degree of hydration is calculated as a function of the temperature and polymer concentration for varied distribution of the copolymer compositions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1112-1123 [ABSTRACT FROM AUTHOR]

Highlights: [•] Benzotriazole, thiophene and trans-stilbene were used to obtain random copolymers. [•] Polymer chain length effect was examined via reaction times and feed ratio. [•] Polymers show processability, multichromicity and fast switching times. [Copyright &y& Elsevier]

Highlights: [•] Two series of novel poly(arylene ether ketone)s were prepared and characterized. [•] Copolymers were synthesized with different degrees of sulfonation. [•] The prepared membranes showed suitable thermal and mechanical stability. [•] Membranes with 45% degree of sulfonation showed good properties for fuel cell. [ABSTRACT FROM AUTHOR]

Abstract: The influence of temperature on the crystallization process of isotactic propylene-1-butylene (P–B) random copolymer with low comonomer concentration subjected to uniaxial tensile force was studied in-situ by using synchrotron-based wide- and small-angle X-ray scattering techniques (WAXS/SAXS). Data analysis was performed on the whole-pattern base. P–B copolymer was stretched at three temperatures, i.e., 100 °C, 60 °C and 25 °C. Before stretching, the static sample contained both γ- and α-phase of isotactic polypropylene (iPP) homopolymer, with the γ-phase being the dominant crystal modification. When subjected to uniaxial stretching, γ-phase adopted a tilted cross-β configuration, with the c-axis forming a tilting angle with respect to the fiber axis at all temperatures. At 100 °C and 60 °C, γ-phase was transformed to α-phase with parallel orientation of polymer chains. Daughter lamellae of the α-phase were observed at 100 °C but not at 60 °C. At room temperature, large lamellar crystals could not be formed due to strong tensile force applied to the polymer network. Low temperature stretching was featured with the formation of mesomorphic phase which was composed of tiny β-form crystals and of about 50% of oriented amorphous phase. The c-axis of the β-form crystal was in parallel to the fiber axis. The crystals were so small that no ordered texture was observed at the length scale of nanometers. [Copyright &y& Elsevier]

A new amphiphilic quaternary random ionomer (PIDHES) was used to construct self-assembly films. PIDHES was prepared by a selective ionization of quaternary random copolymer, poly( N, N-domethyl amimethyl methartylate- co-2-hydroxypropyl methacrylate- co-2-ethylhexyl acrylate- co-styrene) precursor, which was synthesized by free radical copolymerization of commercial hydrophilic monomers N, N-domethyl amimethyl methartylate and 2-hydroxypropyl methacrylate and hydrophobic monomers 2-ethylhexyl acrylate and styrene PIDHES could self-assemble into polymer micelles in water, which underwent orientated deposition in the electric field and ultimately produced secondary assembly films. Scanning electron microscopy studies showed that the resultant PIDHES secondary assembly film was smooth and compact. Moreover, it was found that PIDHES micelles concentration and electric-field-induced time had a strong influence on the morphologies of the resultant secondary assembly film. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

New hybrid poly(hydroxyethyl methacrylate- co-methyl methacrylate)- g-polyhedral oligosilsesquioxane [poly(HEMA- co-MMA)- g-POSS] nanocomposites were synthesized by the combination of reversible addition fragmentation chain transfer (RAFT) polymerization and click chemistry using a grafting to protocol. Initially, the random copolymer poly(HEMA- co-MMA) was prepared by RAFT polymerization of HEMA and MMA. Alkynyl side groups were introduced onto the polymeric backbones by esterification reaction between 4-pentynoic acid and the hydroxyl groups on poly(HEMA- co-MMA). Azide-substituted POSS (POSSN3) was prepared by the reaction of chloropropyl-heptaisobutyl-substituted POSS with NaN3. The click reaction of poly(HEMA- co-MMA)-alkyne and POSSN3 using CuBr/PMDEATA as a catalyst afforded poly(HEMA- co-MMA)- g-POSS. The structure of the organic/inorganic hybrid material was investigated by Fourier transformed infrared, 1H-NMR, and 29Si-NMR. The elemental mapping analysis of the hybrid using X-ray photoelectron spectroscopy and EDX also suggest the formation of poly(HEMA- co-MMA)-anchored POSS nanocomposites. The XRD spectrum of the nanocomposites gives evidence that the incorporation of POSS moiety leads to a hybrid physical structure. The morphological feature of the hybrid nanocomposites as captured by field emission scanning electron microscopy and transmission electron microscopic analyses indicate that a thick layer of polymer brushes was immobilized on the POSS cubic nanostructures. The gel permeation chromatography analysis of poly(HEMA- co-MMA) and poly(HEMA- co-MMA)- g-POSS further suggests the preparation of nanocomposites by the combination of RAFT and click chemistry. The thermogravimetric analysis revealed that the thermal property of the poly(HEMA- co-MMA) copolymer was significantly improved by the inclusion of POSS in the copolymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

A new matrix system for phosphorescent organic light-emitting diodes (OLEDs) based on an electron transporting component attached to an inert polymer backbone, an electronically neutral co-host, and a phosphorescent dye that serves as both emitter and hole conductor are presented. The inert co-host is used either as small molecules or covalently connected to the same chain as the electron-transporting host. The use of a small molecular inert co-host in the active layer is shown to be highly advantageous in comparison to a purely polymeric matrix bearing the same functionalities. Analysis of the dye phosphorescence decay in pure polymer, small molecular co-host film, and their blend lets to conclude that dye molecules distribute mostly in the small molecular co-host phase, where the co-host prevents agglomeration and self-quenching of the phosphorescence as well as energy transfer to the electron transporting units. In addition, the co-host accumulates at the anode interface where it acts as electron blocking layer and improves hole injection. This favorable phase separation between polymeric and small molecular components results in devices with efficiencies of about 47 cd/A at a luminance of 1000 cd/m2. Investigation of OLED degradation demonstrates the presence of two time regimes: one fast component that leads to a strong decrease at short times followed by a slower decrease at longer times. Unlike the long time degradation, the efficiency loss that occurs at short times is reversible and can be recovered by annealing of the device at 180 °C. We also show that the long-time degradation must be related to a change of the optical and electrical bulk properties. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

Abstract: The introduction of functional moieties in the donor polymer (side chains) offers a potential pathway toward selective modification of the nanomorphology of conjugated polymer:fullerene active layer blends applied in bulk heterojunction organic photovoltaics, pursuing morphology control and solar cell stability. For this purpose, two types of poly(3-alkylthiophene) random copolymers, incorporating different amounts (10/30/50%) of ester-functionalized side chains, were efficiently synthesized using the Rieke method. The solar cell performance of the functionalized copolymers was evaluated and compared to the pristine P3HT:PCBM system. It was observed that the physicochemical and opto-electronic characteristics of the polythiophene donor material can be modified to a certain extent via copolymerization without (too much) jeopardizing the OPV efficiency, as far as the functionalized side chains are introduced in a moderate ratio (<30%) and that preference is given to side chains with a small molar volume. A range of complementary techniques – UV–Vis spectroscopy, (modulated temperature) differential scanning calorimetry, transmission electron microscopy and X-ray diffraction analysis – indicated that variations in polymer crystallinity, while maintaining a high level of regioregularity, are probably the main factor responsible for the observed differences. [Copyright &y& Elsevier]

An important issue in the polymerization of a polymer film by plasma-enhanced chemical vapor deposition (PECVD) is how to control the polymer structure. As is generally recognized, it is extremely difficult to control the process because it is very complex. For example, various precursors in the plasma arise from fragmentation of source monomers, which can easily change by varying the plasma conditions. High-energy electrons and ions in the plasma bombard the surface of the deposited film and affect the chemical reaction on the film. Moreover, the droplets that arise from the reactor wall by sputtering will accumulate on the film. However, if we aim to fabricate only a photonically functional polymer film, we will be able to find a solution. In this paper, we propose copolymerization from two types of monomers; one type is used as jointing materials by cracking, and the other is used as a photonic functional segment without serious deformation. This difference of action arises from a difference in the formation enthalpy. To confirm this idea, as an initial step, we copolymerized a film from a mixture of benzene (C6H6) as the functional segment and cyclohexene (C6H10) as the jointing material under the low radio frequency power. The deposited film consists of sp2 bonding clusters surrounded by sp3 bonded (alkyl) networks. We confirmed that the sp2 bonding clusters mostly belong to phenyl, with a few belonging to olefins arising from decomposed C6H6. In addition, the amount of sp2 bonding increases proportionally with increasing ratio of C6H6 in the mixture, and the ratio of phenyl in the film becomes comparable to that of polystyrene. From these facts, we speculate that C6H10 acts as the jointing material and C6H6 as the functional segment. Additionally, we introduced tetrafluorocarbon (CF4) to the plasma. CF4 decomposes with a smaller energy than C6H10, and it forms mainly fluorine and CF3 radicals. The fluorine radical pulls out hydrogen from the film and reacts to form dangling bonds in the film. Moreover, we speculate that they will terminate the dangling bonds. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Abstract: Novel random copolymers containing dithienylcyclopentadienone, thiophene and benzothiadiazole were synthesized and photovoltaic properties of these materials were evaluated. Thermal, structural, optical and electrochemical characterization of the synthesized copolymers was carried out. These thermally stable copolymers are solution processable unlike the homopolymer. The absorption spectra indicated that with the incorporation of alkyl chains in the thiophene moiety, the onset of absorption increases and hence band gap decreases (1.47eV to 1.41eV). Bulk heterojunction solar cells were fabricated with the blend of copolymer and phenyl-C61-butyric acid methyl ester (PCBM) as the active material and device parameters were extracted. The copolymer consists of alkyl thiophene exhibit higher open circuit voltage than the copolymer consisting of thiophene moiety. [Copyright &y& Elsevier]