Showing papers on "Copolymer published in 2017"
TL;DR: A novel wide-bandgap conjugated copolymer based on an imide-functionalized benzotriazole building block containing a siloxane-terminated side-chain is developed and can be a promising candidate toward high-performance all-PSCs for practical applications.
Abstract: A novel wide-bandgap conjugated copolymer based on an imide-functionalized benzotriazole building block containing a siloxane-terminated side-chain is developed. This copolymer is successfully used to fabricate highly efficient all-polymer solar cells (all-PSCs) processed at room temperature with the green-solvent 2-methyl-tetrahydrofuran. When paired with a naphthalene diimide-based polymer electron-acceptor, the all-PSC exhibits a maximum power conversion efficiency (PCE) of 10.1%, which is the highest value so far reported for an all-PSC. Of particular interest is that the PCE remains 9.4% after thermal annealing at 80 °C for 24 h. The resulting high efficiency is attributed to a combination of high and balanced bulky charge carrier mobility, favorable face-on orientation, and high crystallinity. These observations indicate that the resulting copolymer can be a promising candidate toward high-performance all-PSCs for practical applications.
316 citations
TL;DR: In this paper, three basic strategies for forming stimuli-responsive polymers are considered: RAFT polymerization of functional monomers, the post-polymerization modification of RAFT-synthesized polymers, and the use of functional RAFT agents and RAFT end-group transformation (often “grafting from”).
230 citations
TL;DR: A sulfur-rich copolymer@carbon nanotubes hybrid cathode is introduced for lithium-sulfur batteries produced by combining the physical and chemical confinement of polysulfides.
Abstract: A sulfur-rich copolymer@carbon nanotubes hybrid cathode is introduced for lithium-sulfur batteries produced by combining the physical and chemical confinement of polysulfides. The binderfree and metal-current-collector-free cathode of dual confinement enables an efficient pathway for the fabrication of high-performance sulfur copolymer carbon matrix electrodes for lithium-sulfur batteries.
229 citations
TL;DR: This current review presents a comprehensive description of rROP, which combines the advantages of both ring-opening polymerization and radical polymerization, that is the preparation of polymers bearing heteroatoms in the backbone but with the ease and robustness of a radical process.
Abstract: Cyclic monomers bearing either vinyl or exomethylene groups have the ability to be polymerized through a radical pathway via a ring-opening mechanism (addition–fragmentation process), leading to the introduction of functionalities in the polymer backbone. Radical ring-opening polymerization (rROP) combines the advantages of both ring-opening polymerization and radical polymerization, that is the preparation of polymers bearing heteroatoms in the backbone but with the ease and robustness of a radical process. This current review presents a comprehensive description of rROP by detailing: (i) the various monomers that polymerize through rROP; (ii) the main parameters that govern the rROP mechanism; (iii) the copolymerization by conventional or controlled/living radical polymerization between rROP monomers and traditional vinyl monomers to obtain copolymers with advanced properties; (iv) the different applications (low shrinkage materials and preparation of (bio)degradable materials) of rROP monomer-containin...
200 citations
TL;DR: In this article, the authors highlight advances in copolymerization of carbon dioxide and epoxides (oxiranes) to produce polycarbonates, focusing on starting materials that have been generated from renewable feedstocks including straight-chain alkylene oxides, cyclohexadiene oxide, and limonene oxide.
191 citations
TL;DR: In this article, a dibenzobarrelene-derived α-diimine nickel precatalysts for living copolymerization of ethylene and methyl 10-undecenoate were reported.
Abstract: Development of thermally stable nickel-based catalysts is highly desirable for industrial gas-phase olefin polymerizations. On the basis of the strategy of promoting the thermostability of nickel catalyst by the ligand backbone, we herein reported novel dibenzobarrelene-derived α-diimine nickel precatalysts for ethylene polymerization. Increasing the steric bulk on the ligand backbone was expected to inhibit the N-aryl rotation of the α-diimine ligands by the repulsive interactions, thus enhancing thermal stability (100 °C) and living fashion a temperatures up to 80 °C. Bulk ligand backbone also improved tolerance of nickel catalyst toward polar groups, and the α-diimine nickel catalyst containing a 2,6-tBu-dibenzobarrelene backbone catalyzed living copolymerization of ethylene and methyl 10-undecenoate.
176 citations
TL;DR: In this article, the copolymers were characterized by infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), dynamic rheology and swelling measurements.
171 citations
TL;DR: In this paper, a review of recent developments on late transition metal catalyzed α-olefin polymerization and copolymerization with polar comonomers is described, focusing on the regio-and stereo-selectivity induced by late-transition metal catalysts in these reactions.
Abstract: In this review, recent developments on late transition metal catalyzed α-olefin polymerization and copolymerization with polar comonomers are described. First, the polymerization mechanisms of early and late transition metal catalyzed α-olefin polymerization are compared. Second, cationic catalysts bearing α-diimine and related ligands as well as neutral catalysts bearing anionic ligands for α-olefin homopolymerization are discussed in detail. Third, late transition metal catalyzed α-olefin copolymerization with polar functionalized comonomers is summarized. Special attention is paid to the regio- and stereo-selectivity induced by late transition metal catalysts in these polymerization and copolymerization reactions.
168 citations
TL;DR: In this article, a benchtop approach is developed for the synthesis of various polymeric architectures using an aqueous Reversible Addition-Fragmentation chain Transfer (RAFT) photopolymerization technique.
168 citations
TL;DR: The injectable thermoresponsive hydrogels formed by alginate-g-PNIPAAm and loaded with DOX turned into a smart drug delivery system, releasing DOX-encapsulated micelles in a sustained manner, showing great potential for overcoming the drug resistance in cancer therapy.
Abstract: In this work, we have synthesized a thermoresponsive copolymer, alginate-g-poly(N-isopropylacrylamide) (alginate-g-PNIPAAm) by conjugating PNIPAAm to alginate, where PNIPAAm with different molecular weights and narrow molecular weight distribution was synthesized by atomic transfer radical polymerization. The copolymer dissolved in water or phosphate-buffered saline buffer solution at room temperature and formed self-assembled micelles with low critical micellization concentrations when the temperature increased to above their critical micellization temperatures. At higher concentration, that is, 7.4 wt % in water, the copolymer formed solutions at 25 °C and turned into thermosensitive hydrogels when temperature increased to the body temperature (37 °C). Herein, we hypothesized that the thermoresponsive hydrogels could produce self-assembled micelles with the dissolution of the alginate-g-PNIPAAm hydrogels in a biological fluid or drug release medium. If the drug was hydrophobic, the hydrogel eventually c...
154 citations
TL;DR: The development of a new protocell model through the spontaneous interfacial self-assembly of copolymer molecules on biopolymer coacervate microdroplets is presented, demonstrating striking integrity as a result of membrane formation and paving the way for the development of new synthetic cell constructs.
Abstract: Complex coacervate microdroplets are finding increased utility in synthetic cell applications due to their cytomimetic properties. However, their intrinsic membrane-free nature results in instability that limits their application in protocell research. Herein, we present the development of a new protocell model through the spontaneous interfacial self-assembly of copolymer molecules on biopolymer coacervate microdroplets. This hierarchical protocell model not only incorporates the favorable properties of coacervates (such as spontaneous assembly and macromolecular condensation) but also assimilates the essential features of a semipermeable copolymeric membrane (such as discretization and stabilization). This was accomplished by engineering an asymmetric, biodegradable triblock copolymer molecule comprising hydrophilic, hydrophobic, and polyanionic components capable of direct coacervate membranization via electrostatic surface anchoring and chain self-association. The resulting hierarchical protocell demo...
TL;DR: The use of palladium catalysts in olefin polymerization and copolymerization has evolved rapidly as discussed by the authors, and high performance phosphine-sulfonate-based nickel catalysts were developed.
Abstract: Use of palladium catalysts in olefin polymerization and copolymerization has evolved rapidly. In contrast, earth-abundant and low-cost nickel catalysts generally suffer from drawbacks that include low thermal stability and generation of low-molecular-weight polymers in the presence of polar monomers. By taking advantage of several design strategies, high-performance phosphine-sulfonate-based nickel catalysts were developed. These nickel catalysts demonstrated high activities and thermal stabilities to afford high-molecular-weight polyethylene. Most importantly, high-molecular-weight copolymers could be generated through the copolymerization of ethylene with a variety of polar monomers.
TL;DR: Control experiments and computational results reveal the critical role of the metal-nitrogen interaction in these polymerization and copolymerization reactions.
Abstract: Transition-metal-catalyzed copolymerization reactions of olefins with polar-functionalized comonomers are highly important and also highly challenging. A second-coordination-sphere strategy was developed to address some of the difficulties encountered in these copolymerization reactions. A series of α-diimine ligands bearing nitrogen-containing second coordination spheres were prepared and characterized. The properties of the corresponding nickel and palladium catalysts in ethylene polymerizations and copolymerizations were investigated. In the nickel system, significant reduction in polymer branching density was observed, while lower polymer branching densities, as well as a wider range of polar monomer substrates, were achieved in the palladium system. Control experiments and computational results reveal the critical role of the metal-nitrogen interaction in these polymerization and copolymerization reactions.
TL;DR: A detailed mechanistic study on the self-assembly and gelation behavior of a class of ABA triblock copolymers containing a central poly(ethylene oxide) block and terminal polycarbonate blocks with pendant 1,2-dithiolane functionalities.
Abstract: The use of dithiolane-containing polymers to construct responsive and dynamic networks is an attractive strategy in material design. Here, we provide a detailed mechanistic study on the self-assembly and gelation behavior of a class of ABA triblock copolymers containing a central poly(ethylene oxide) block and terminal polycarbonate blocks with pendant 1,2-dithiolane functionalities. In aqueous solution, these amphiphilic block copolymers self-assemble into bridged flower micelles at high concentrations. The addition of a thiol initiates the reversible ring-opening polymerizations of dithiolanes in the micellar cores to induce the cross-linking and gelation of the micellar network. The properties of the resulting hydrogels depend sensitively on the structures of 1,2-dithiolanes. While the methyl asparagusic acid-derived hydrogels are highly dynamic, adaptable, and self-healing, those derived from lipoic acid are rigid, resilient, and brittle. The thermodynamics and kinetics of ring-opening polymerization ...
TL;DR: In this paper, the authors demonstrate how block copolymer hydrophobicity allows control over aggregate morphology in water and leads to remarkable control over the length of polymeric nanoparticle worms.
Abstract: Hydrophobicity inherently affects a solutes behavior in water, yet how polymer chain hydrophobicity impacts aggregate morphology during solution self-assembly and reorganization is largely overlooked. As polymer and nanoparticle syntheses are easily achieved, the resultant nanoparticle architectures are usually attributed to chain topology and overall degree of polymerization, bypassing how the chains may interact with water during/after self-assembly to elicit morphology changes. Herein, we demonstrate how block copolymer hydrophobicity allows control over aggregate morphology in water and leads to remarkable control over the length of polymeric nanoparticle worms. Polymerization-induced self-assembly facilitated nanoparticle synthesis through simultaneous polymerization, self-assembly, and chain reorganization during a block copolymer chain extension from a hydrophilic poly(N,N-dimethylacrylamide) macro-chain-transfer agent with diacetone acrylamide and N,N-dimethylacrylamide. Slight variations in the m...
TL;DR: A novel recyclable plastic: degradable polycarbonate synthesized by dinuclear chromium-complex-mediated copolymerization of CO2 with 1-benzyloxycarbonyl-3,4-epoxy pyrrolidine, a meso-epoxide in quantitative yield under mild reaction conditions is reported.
Abstract: It is of great significance to depolymerize used or waste polymers to recover the starting monomers suitable for repolymerization reactions that reform recycled materials no different from the virgin polymer. Herein, we report a novel recyclable plastic: degradable polycarbonate synthesized by dinuclear chromium-complex-mediated copolymerization of CO2 with 1-benzyloxycarbonyl-3,4-epoxy pyrrolidine, a meso-epoxide. Notably, the novel polycarbonate with more than 99 % carbonate linkages could be recycled back into the epoxide monomer in quantitative yield under mild reaction conditions. Remarkably, the copolymerization/depolymerization processes can be achieved by the ON/OFF reversible temperature switch, and recycled several times without any change in the epoxide monomer and copolymer. These characteristics accord well with the concept of perfectly sustainable polymers.
TL;DR: The results from such a kind of comparable study among phenol, catechol, and gallol suggests that tridentate structure should be better than bidentates structure for bonding to the surface.
TL;DR: This novel molecular recognition strategy to trigger morphological transitions via dynamic covalent chemistry offers considerable scope for the design of new stimulus-responsive copolymer vesicles (and hydrogels) for targeted delivery and controlled release of cargoes.
Abstract: Dynamic covalent chemistry is exploited to drive morphological order–order transitions to achieve the controlled release of a model payload (e.g., silica nanoparticles) encapsulated within block copolymer vesicles. More specifically, poly(glycerol monomethacrylate)–poly(2-hydroxypropyl methacrylate) (PGMA–PHPMA) diblock copolymer vesicles were prepared via aqueous polymerization-induced self-assembly in either the presence or absence of silica nanoparticles. Addition of 3-aminophenylboronic acid (APBA) to such vesicles results in specific binding of this reagent to some of the pendent cis-diol groups on the hydrophilic PGMA chains to form phenylboronate ester bonds in mildly alkaline aqueous solution (pH ∼ 10). This leads to a subtle increase in the effective volume fraction of this stabilizer block, which in turn causes a reduction in the packing parameter and hence induces a vesicle-to-worm (or vesicle-to-sphere) morphological transition. The evolution in copolymer morphology (and the associated sol–gel...
TL;DR: The structure-property relationships gleaned from this survey of different zwitterion structures serves as a guideline to develop new zwatterionic materials for various applications such as membranes, drug delivery, and sensors.
Abstract: Membranes with high flux, ∼1 nm pore size, and unprecedented protein fouling resistance were prepared by forming selective layers of self-assembling zwitterionic amphiphilic random copolymers on porous supports by a simple coating method. Random copolymers were prepared from the hydrophobic monomer 2,2,2-trifluoroethyl methacrylate (TFEMA) and four zwitterionic monomers (sulfobetaine methacrylate, sulfobetaine 2-vinylpyridine, sulfobutylbetaine 2-vinylpyridine, and 2-methacryloyloxyethyl phosphorylcholine) by free radical polymerization. All copolymers microphase separated to form bicontinuous ∼1.2 nm nanodomains with the zwitterionic domains acting as nanochannels for the permeation of water and solutes. The resultant membranes all had a ∼1 nm size cutoff independent of zwitterion chemistry. There were, however, significant differences in the hydrophilicity, water uptake, water flux, and fouling resistance among membranes prepared with different zwitterionic monomers. Membranes prepared from the copolyme...
TL;DR: Ni(II) complexes bearing an o-bis(aryl)phosphinophenolate ligand were synthesized as catalysts for copolymerization of ethylene and alkyl acrylates to give highly linear and high molecular weight copolymers.
Abstract: Ni(II) complexes bearing an o-bis(aryl)phosphinophenolate ligand were synthesized as catalysts for copolymerization of ethylene and alkyl acrylates. When the P-bound aryl group was 2,6-dimethoxyphenyl group, one of the oxygen atoms in the methoxy groups coordinated to the nickel center on its apical position. This complex was a highly active catalyst without any activators to give highly linear and high molecular weight copolymers. The structures of the copolymers were determined by 1H and 13C NMR to clarify that the alkyl acrylate comonomers were incorporated in the main chain and that the structures of the copolymers were significantly influenced by the structure of the aryl group in the ligand.
TL;DR: In this article, high sulfur content copolymers were prepared via the inverse vulcanization of elemental sulfur with styrene and used as active cathode material in Li-S batteries.
Abstract: High sulfur content copolymers were prepared via the inverse vulcanization of elemental sulfur with styrene. This reaction was carried out at a relatively low temperature and invokes a new chain transfer mechanism of abstraction of benzylic protons to form stable copolymers. The use of styrene as a comonomer for inverse vulcanization was attractive due to the low cost and wide spread industrial use of styrenics in free radical processes. The copolymers were used as the active cathode material in Li-S batteries that exhibited outstanding device performance, maintaining 489 mAh/g capacity after 1000 cycles. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 107–116
TL;DR: A polyethylene glycol unit is introduced to some phosphine-sulfonate palladium and nickel catalysts, and its influence on ethylene polymerization and copolymerization is investigated, which leads to enhanced activity, catalyst stability, and increased polyethylenes molecular weight.
Abstract: The transition-metal-catalyzed copolymerization of olefins with polar functionalized co-monomers represents a major challenge in the field of olefin polymerization It is extremely difficult to simultaneously achieve improvements in catalytic activity, polar monomer incorporation, and copolymer molecular weight through ligand modifications Herein we introduce a polyethylene glycol unit to some phosphine-sulfonate palladium and nickel catalysts, and its influence on ethylene polymerization and copolymerization is investigated In ethylene polymerization, this strategy leads to enhanced activity, catalyst stability, and increased polyethylene molecular weight In ethylene copolymerization with polar monomers, improvements in all copolymerization parameters are realized This effect is most significant for polar monomers with hydrogen-bond-donating abilities
TL;DR: The crystallogenesis of a recombinantly produced membrane protein that never left a lipid bilayer environment is reported, as an alternative to approaches mediated by conventional detergents.
TL;DR: In this article, single-ion conducting polymer electrolytes represent the ideal solution to reduce concentration polarization in lithium metal batteries (LMBs) and are obtained by reversible addition of fragmentation chain transfer polymerization, showing low glass transition temperature (−55 to 7°C) and degree of crystallinity (51-0%).
TL;DR: The approach disclosed in this work constitutes a powerful strategy for the synthesis of polymers spanning the linear-to-bottlebrush regimes with controlled grafting density and side chain distribution, molecular attributes that dictate micro- and macroscopic properties.
Abstract: Control over polymer sequence and architecture is crucial to both understanding structure–property relationships and designing functional materials. In pursuit of these goals, we developed a new synthetic approach that enables facile manipulation of the density and distribution of grafts in polymers via living ring-opening metathesis polymerization (ROMP). Discrete endo,exo-norbornenyl dialkylesters (dimethyl DME, diethyl DEE, di-n-butyl DBE) were strategically designed to copolymerize with a norbornene-functionalized polystyrene (PS), polylactide (PLA), or polydimethylsiloxane (PDMS) macromonomer mediated by the third-generation metathesis catalyst (G3). The small-molecule diesters act as diluents that increase the average distance between grafted side chains, generating polymers with variable grafting density. The grafting density (number of side chains/number of norbornene backbone repeats) could be straightforwardly controlled by the macromonomer/diluent feed ratio. To gain insight into the copolymer ...
TL;DR: Enzymatic polymerization represents today an effective and preferable alternative to conventional chemically-catalyzed processes, and offers significant advantages, summarized in the applied mild reaction conditions mainly in terms of temperature and toxicity, and high selectivity of enzymes, resulting in improved quality/performance of end products.
TL;DR: Various carboxylic acid-functionalized poly(N,N-dimethylacrylamide) macromolecular chain transfer agents (macro-CTAs) were chain-extended with diacetone acrylamides (DAAM) by reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization to produce a series of diblock copolymer nano-objects via polymerization-induced self-assembly (PISA).
Abstract: Various carboxylic acid-functionalized poly(N,N-dimethylacrylamide) (PDMAC) macromolecular chain transfer agents (macro-CTAs) were chain-extended with diacetone acrylamide (DAAM) by reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization at 70 °C and 20% w/w solids to produce a series of PDMAC–PDAAM diblock copolymer nano-objects via polymerization-induced self-assembly (PISA). TEM studies indicate that a PDMAC macro-CTA with a mean degree of polymerization (DP) of 68 or higher results in the formation of well-defined spherical nanoparticles with mean diameters ranging from 40 to 150 nm. In contrast, either highly anisotropic worms or polydisperse vesicles are formed when relatively short macro-CTAs (DP = 40–58) are used. A phase diagram was constructed to enable accurate targeting of pure copolymer morphologies. Dynamic light scattering (DLS) and aqueous electrophoresis studies indicated that in most cases these PDMAC–PDAAM nano-objects are surprisingly resistant to chan...
TL;DR: This method facilitates high-throughput PISA, allowing for the construction of a detailed phase diagram in a rather short time and the potential bio-related application of this method by the successful encapsulation of horseradish peroxidase and bovine serum albumin into self-assembled polymer vesicles without compromising protein activities.
Abstract: High-throughput synthesis of well-defined polymer nano-objects has long been an attractive yet challenging topic in the area of polymer chemistry and material science. Herein, we report an enzyme-assisted photoinitiated polymerization-induced self-assembly (photo-PISA) approach to prepare well-defined AB diblock or ABC triblock copolymer nano-objects at room temperature in open vessels and multiwell plates. Kinetic studies indicated that the presence of glucose oxidase (GOx) endowed the polymerizations with excellent oxygen tolerance. Good control was maintained during the enzyme-assisted photo-PISA process. This method facilitates high-throughput PISA, allowing for the construction of a detailed phase diagram in a rather short time. We also demonstrate the potential bio-related application of this method by the successful encapsulation of horseradish peroxidase (HRP) and bovine serum albumin (BSA) into self-assembled polymer vesicles without compromising protein activities. This robust oxygen-tolerant PI...
TL;DR: Copolymerization of cyclopentene oxide and CO2 was performed, resulting in the highest reported TOF of 3200 h-1 together with 99% polycarbonate selectivity, and two-dimensional NMR spectroscopy and polarimetry provided a deeper understanding of the underlying mechanism.
Abstract: Terpolymerizations of (rac)-β-butyrolactone (BBL), cyclohexene oxide (CHO), and carbon dioxide were realized in one-pot reactions utilizing a Lewis acid BDICF3-Zn-N(SiMe3)2 (1) catalyst. The type of polymerization can be regulated and switched between ring-opening polymerization (ROP) of BBL and CHO/CO2 copolymerization by the presence of CO2 in the reaction mixture. Applying 3 bar CO2 to the three-component system leads to similar reaction rates for copolymerization and ROP and therefore to a terpolymer with a statistical composition, whereas 40 bar CO2 affords exclusive copolymerization of CHO/CO2. Two-dimensional NMR spectroscopy and polarimetry provided a deeper understanding of the underlying mechanism. Furthermore, copolymerization of cyclopentene oxide (CPO) and CO2 was performed, resulting in the highest reported TOF of 3200 h–1 together with 99% polycarbonate selectivity. Terpolymerizations of CPO/CO2 and BBL were successfully conducted using the established reaction pathways.
TL;DR: The introduction of a host-guest interaction based on CDs enables the aqueous dispersion polymerization of water-immiscible monomers, and produces kinetically trapped nanostructures, which could be a powerful technique for nanomaterials synthesis.
Abstract: A one-step synthesis of nanotubes by RAFT dispersion polymerization of cyclodextrin/styrene (CD/St) complexes directly in water is presented. The resulted amphiphilic PEG-b-PS diblock copolymers self-assemble in situ into nanoparticles with various morphologies. Spheres, worms, lamellae, and nanotubes were controllably obtained. Because of the complexation, the swelling degree of polystyrene (PS) blocks by free St is limited, resulting in limited mobility of PS chains. Consequently, kinetically trapped lamellae and nanotubes were obtained instead of spherical vesicles. During the formation of nanotubes, small vesicles first formed at the ends of the tape-like lamellae, then grew and fused into nanotubes with a limited chain rearrangement. The introduction of a host–guest interaction based on CDs enables the aqueous dispersion polymerization of water-immiscible monomers, and produces kinetically trapped nanostructures, which could be a powerful technique for nanomaterials synthesis.