ACS polymers Au最新文献

Recent studies have revealed that cardiac tissue regeneration is promoted by administering an initial dose of exogenous lactate and locally maintaining an abundant concentration of this compound for a prolonged period (i.e., around 10-14 days) through sustained release. The aim of this study is to develop a scaffold based on poly-(lactic acid) (PLA) for achieving a sustained daily release of lactate from the first day to the end of the recommended period. First, a five-layered electroresponsive scaffold has been engineered using three PLA layers (first, third, and fifth), each composed of electrospun microfibers (MFs), separated by spin coated lactate (second) and poly-(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PEDOT:PSS) (fourth) intermediate layers. The hydrophobicity of the outer PLA layers (first and fifth) has been used to maintain the release of lactate from the intermediate second layer over 3 days, while the conducting fourth PEDOT:PSS layer has ensured a complete lactate release by electrostimulation. After that, in a second step, the same scaffold has been re-engineered to maintain the sustained release not only for a short period (3 days) but also for a prolonged period (>10 days). For this purpose, the PLA MFs of the intermediate third layer have been substituted by plasma-treated proteinase K-containing PLA MFs, obtained by electrospinning a PLA:enzyme mixture. The activity of the enzyme, which decomposes the ester bonds of PLA, combined with the effect of the plasma on the PLA structure, results in a prolonged sustained release that, in addition, can be modulated.

Materials derived from natural sources are demanded for future applications due to the combination of factors such as sustainability increase and legislature requirements. The availability and efficient analysis of vegetable oils (triacylglycerides) open an enormous potential for incorporating these compounds into various products to ensure the ecological footprint decreases and to provide advantageous properties to the eventual products, such as flexibility, toughness, or exceptional hydrophobic character. The double bonds located in many vegetable oils are centers for chemical functionalization, such as epoxidization, hydroxylation, or many nucleophile substitutions using acids or anhydrides. Naturally occurring castor oil comprises a reactive vacant hydroxyl group, which can be modified via numerous chemical approaches. This comprehensive Review provides an overall insight toward multiple materials utilities for functionalized glycerides such as additive manufacturing (3D printing), polyurethane materials (including their chemical recycling), coatings, and adhesives. This work provides a complex list of investigated and studied applications throughout the available literature and describes the chemical principles for each selected application.

Polysiloxane is an industrially important polymer, as it serves as the platform for the preparation of silicone materials with excellent thermal stability. Even though the fact that introducing rotaxanes into a polymer network provides a novel way to build new materials with peculiar mechanical properties is well-known, this tactic has rarely been applied to silicones, perhaps due to the lack of efficient synthetic methods. Here, in this work, we report the preparation and characterization of novel rotaxanated silicone elastomers by a simple two-step synthetic method. Starting from commercially available γ-cyclodextrin (CD) and vinyl-terminated polydimethylsiloxane, poly[(dimethylsiloxane)-pseudorotaxa-(γ-cyclodextrin)]s were facilely prepared. These pseudopolyrotaxanes were then used to prepare silicone elastomers of different structures and compositions. Mechanical tests of these elastomers show that they have moderate tensile strength but an excellent extension ratio (∼800% for the sample with the highest extension ratio). γ-CD plays a unique and important role in shaping the network's topological structure and mechanical properties. This role was unveiled by applying various techniques such as solid-state NMR measurements and cyclic tensile tests to the elastomers obtained. Due to the simplicity of the current method, it may be used for large-scale preparation of stretchy silicone rubbers with optimum mechanical properties.

Recently, it has been reported that various polymethacrylates synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization may be depolymerized by heating them to 120 °C in solution. However, insights into the mechanisms and kinetics remain limited. In this work, we monitored the depolymerization process of poly(benzyl methacrylate) in p-xylene using time-resolved small-angle X-ray scattering (SAXS). The results revealed that the weight-average molecular weight gradually decreased, while the z-average radius of gyration remained almost unchanged until approximately half of the repeating units were converted. This unexpected behavior could be well-reproduced by a kinetic model of end-to-end depolymerization (unzipping). This study provides the first direct observation of the structural evolution during depolymerization via an unzipping mechanism.