The first two asymmetric‐indenothiophene‐based donor–acceptor copolymers (PITBT and PITFBT) are prepared through Stille coupling reactions between distannyl indenothiophene and brominated ...benzothiadiazole derivatives. The best performing solar cell fabricated from PITFBT exhibits a power conversion efficiency of 9.14% which demonstrates a great potential of the asymmetric indenothiophene for high‐performance copolymers.
Display omitted
•MPEG-PLA improved the compatibility of PLA-based blends.•MPEG-PLA improved the ductility of the PLA/PBAT blends (296% vs. 30%).•MPEG-PLA improved the interfacial adhesion of the ...blends.
Block copolymer is an effective compatibilizer for PLA-based biodegradable polyester blends to improve the mechanical properties. However, how to find an “A-C” type of di-block copolymer as a common compatibilizer for improving the miscibility of A and B blends is very challenging. In this research, monomethoxy poly(ethylene glycol)-polylactide (MPEG-PLA) di-block copolymers were synthesized for compatibilization of PLA-based polyester blends, such as PLA with poly(butylene adipate-co-terephthalate) (PBAT), or poly(butylene succinate) (PBS), or poly(butylene succinate-co-adipate) (PBSA). The results showed that the di-block successfully reduced the interfacial tension and improved the interfacial adhesion, thereby, the size of dispersed phase decreased from 2 μm to 0.3 μm with the addition of MPEG-PLA copolymer which the segment ratio of EG/LA was 2.5 in PLA/PBAT blends. Moreover the elongation at the break of the blends was as high as 296%, which was ten times more than the pristine blends. Furthermore the MPEG-PLA di-block copolymer with specific structure improved the mechanical properties and changed the phase morphology of PLA/PBS and PLA/PBSA blends. In the blends, PEG segment in “A-C” di-block copolymer acted as B blocks in “A-B” di-block copolymers to improve the compatibility of PLA-based biodegradable polymer blends.
Atomistic simulation is reported for micro-phase separation and H2 diffusion in poly(ethylene oxide) (PEO)apoly(butylene terephthalate) (PBT) multiblock copolymers with varying PEO segment length. ...The simulated densities of copolymers agree well with available experimental data with only 1a2% deviations. A strong interaction exists between PEO segments as evidenced by the sharp peaks in radial distribution functions. With increasing PEO segment length, the fractional free volume marginally increases, PEO and PBT segments tend to be more immiscible and segregated domain size increases. This is consistent with experimental and theoretical studies in the literature. The mobility of PBT segments is almost one order of magnitude smaller than that of PEO segments. With increasing PEO segment length, the mobility of PEOaPBT copolymers is enhanced. For H2 diffusion in PEOaPBT copolymers, the diffusivity increases with increasing PEO segment length, as experimentally observed. This simulation study provides atomistic insight into the micro-structure and gas transport properties in PEOaPBT copolymers.
Cocrystallization involving two or more components aggregating into cocrystals allows the preparation of materials with markedly improved charge mobility. This approach however, is little explored in ...all‐conjugated block copolymers (BCPs). Herein, we report the first investigation into the correlation between cocrystals and charge mobility in a series of new all‐conjugated BCPs: poly(3‐butylthiophene)‐b‐poly(3‐hexylselenophene) (P3BT‐b‐P3HS) for high‐performance field‐effect transistors. These rationally synthesized rod–rod BCPs self‐assemble into cocrystals with high charge mobilities. Upon one‐step thermal annealing, their charge mobilities decrease slightly despite their increased crystallinities. After two‐step thermal annealing, P3BT‐b‐P3HS (P3BT/P3HS=2:1) and (1:1) cocrystals disappear and phase separation occurs, leading to greatly decreased charge mobilities. In contrast, P3BT‐b‐P3HS (1:2) retains its cocrystalline structure and its charge mobility.
All‐conjugated diblock copolymers poly(3‐butylthiophene)‐b‐ poly(3‐hexylselenophene) (P3BT‐b‐P3HS) self‐assemble into cocrystals in thin films, exhibiting high charge mobility without post‐thermal or solvent‐vapor annealing. The strong correlation between different P3BT‐b‐P3HS crystalline structures and the field‐effect mobilities was unraveled for the first time.
Vinyl polymers are the focus of intensive research due to their ease of synthesis and the possibility of making well-defined, functional materials. However, their non-degradability leads to ...environmental problems and limits their use in biomedical applications, allowing aliphatic polyesters to still be considered as the gold standards. Radical ring-opening polymerization of cyclic ketene acetals is considered the most promising approach to impart degradability to vinyl polymers. However, these materials still exhibit poor hydrolytic degradation and thus cannot yet compete with traditional polyesters. Here we show that a simple copolymerization system based on acrylamide and cyclic ketene acetals leads to well-defined and cytocompatible copolymers with faster hydrolytic degradation than that of polylactide and poly(lactide-co-glycolide). Moreover, by changing the nature of the cyclic ketene acetal, the copolymers can be either water-soluble or can exhibit tunable upper critical solution temperatures relevant for mild hyperthermia-triggered drug release. Amphiphilic diblock copolymers deriving from this system can also be formulated into degradable, thermosensitive nanoparticles by an all-water nanoprecipitation process.
In this work, lignin was used as a heterogeneous nucleating agent to increase polylactic acid (PLA) crystallinity. To enhance the gas barrier performance of PLA/LG composite films, two graft ...copolymers, polylactide‐graft‐glycidyl methacrylate (PLA‐g‐GMA) and polylactide‐graft‐poly (ethylene glycol) methyl ether methacrylate (PLA‐g‐PEGMA) were successfully synthesized and separately used as compatibilizers to modify PLA/LG composite properties such as interfacial adhesion, crystallinity, and mechanical properties. Since crystallites can act as obstacles to gas diffusion, the higher the crystallinity of the polymer matrix, the better gas barrier performance of the composite film will be. The crystallinity and crystalline structure of the PLA matrix was demonstrated by wide‐angle X‐ray diffraction and differential scanning calorimetry results. Since LG particles can act as efficient heterogeneous crystal nucleating agents, a roughly 50% reduction in oxygen permeability (PO2) was obtained by adding 1 phr LG to the PLA matrix (PLA/1LG). Following addition of 10 phr PLA‐g‐GMA to the PLA/LG composite, PLA/PLA‐g‐GMA/LG composite films showed lower gas barrier properties than PLA/LG composites without added compatibilizer. Moreover, the interfacial adhesion of PLA/LG composites was significantly improved after addition of PLA‐g‐GMA. Therefore, PLA/PLA‐g‐GMA/3LG showed the highest tensile strength, 33% higher than that of neat PLA. Following addition of 10 phr PLA‐g‐PEGMA to the PLA/LG composite, the long liner side chains of PLA‐g‐PEGMA were able to act as nucleating agents for PLA to promote the crystallization of PLA. Accordingly, PLA/PLA‐g‐PEGMA/3LG with 3 phr LG showed a roughly 86% reduction in PO2 when compared with neat PLA film.
Free‐radical copolymerization of cyclic ketene acetals (CKAs) and vinyl ethers (VEs) was investigated as an efficient yet simple approach for the preparation of functional aliphatic polyesters. The ...copolymerization of CKA and VE was first predicted to be quasi‐ideal by DFT calculations. The theoretical prediction was experimentally confirmed by the copolymerization of 2‐methylene‐1,3‐dioxepane (MDO) and butyl vinyl ether (BVE), leading to rMDO=0.73 and rBVE=1.61. We then illustrated the versatility of this approach by preparing different functional polyesters: 1) copolymers functionalized by fluorescent probes; 2) amphiphilic copolymers grafted with poly(ethylene glycol) (PEG) side chains able to self‐assemble into PEGylated nanoparticles; 3) antibacterial films active against Gram‐positive and Gram‐negative bacteria (including a multiresistant strain); and 4) cross‐linked bioelastomers with suitable properties for tissue engineering applications.
VE/CKA, the ideal couple: The radical copolymerization between cyclic ketene acetal (CKA) monomers and vinyl ether (VE) derivatives led to a new and easy way to prepare homogeneously functionalized aliphatic polyesters (left to right in picture: nanoparticles, bioelastomers, antibacterial surfaces).
Multicomponent nanostructured materials assembled from molecular building blocks received wide attention due to their precisely integrated multifunctionalities. However, discovery of these materials ...with desirable composition and morphology was limited by their low synthetic scalability and narrow structural tuning window with given building blocks. Here, we report a scalable and diversity‐oriented synthetic approach to hierarchically structured nanomaterials based on a few readily accessible building blocks. Mixed‐graft block copolymers containing sequence‐defined side chains were prepared through ring‐opening metathesis copolymerization of three or four types of macromonomers. Intramolecularly defined interfaces promoted the formation of ordered hierarchical structures with lattice sizes tunable across multiple length scales. The same set of macromonomers were arranged and combined in different ways, providing access to diverse morphologies in the resultant structures.
Mixed‐graft block copolymers containing sequence‐defined side chains were synthesized from three or four different types of macromonomers. The morphology of hierarchical nanostructures assembled from the prepared graft copolymers was readily diversified by varying the sequence, number, and molar ratio of the side chains.
