Macromolecular Rapid Communications最新文献

In this work, we investigated the depolymerization behavior of bromine-terminated poly(isopropenylboronic acid pinacol ester) [poly(IPBpin)] by copper catalyst in comparison with poly(methyl methacrylate) (PMMA), whose depolymerization behaviors have been extensively studied. Halogen-terminated poly(IPBpin)s were precisely synthesized via copper-mediated reversible deactivation radical polymerization with a bromide initiator. In the presence of a copper catalyst, the IPBpin polymers underwent depolymerization to regenerate the monomer (i.e., IPBpin) at temperatures below 100°C, in contrast to the inert behavior of bromine-terminated PMMA under the same conditions. The ceiling temperature was determined to be 76°C (1.0 M), which was much lower than that of PMMA (202°C, 1.0 M). Notably, despite exhibiting superior depolymerizability to PMMA, the IPBpin polymers showed comparable or even higher thermal stability.

Reversible sol-gel transitions are difficult to achieve in conventional water-swollen hydrogels in open aqueous environments, because polymer chains dissolve or diffuse once the network disassembles. Here, we present a proof-of-concept to overcome this limitation by introducing a water-immiscible and non-cytotoxic ionic liquid (IL) phase that confines polymer networks and prevents dissolution during reversible phase transitions. We report a photoreversible ion gel that crosses the rheological boundary (tan δ ∼ 1) under light, enabling reversible sol-gel switching within this closed IL environment. The material integrates an ABC triblock copolymer, P(AzoAm-r-NIPAm)-b-PBuA-b-PSt, with a solvent-quality-tunable blend of non-cytotoxic ILs ([P4,4,4,1][TFSI]/[P8,8,8,8][TFSI]). The photoresponsive A-block, P(AzoAm-r-NIPAm), exhibits a polarity-dependent solubility change with the cis/trans isomerization of azobenzene, providing a reversible light-controlled self-assembly. Time-resolved rheology confirmed repeated crossings of tan δ = 1 under alternating UV-vis illumination at 52°C. The switching mechanism is governed by the lifetime of reversible junctions, consistent with transient network theory. In addition, hMSCs adhered to and spread on the ion gel at 37°C, indicating the cytocompatibility of the ion gel itself. This light-programmable, water-immiscible ion gel has the potential to provide a reversible liquid-solid mechanical cue for next-generation mechanobiology.

Semi-crystalline polymers are widely utilized due to their favorable cost, and their crystallization behavior is significantly influenced by crystallization temperature. In this study, we employed AFM-based SMFS (single-molecule force spectroscopy) to investigate single-chain folding structures in Polyethylene Oxide (PEO) at various crystallization temperatures (T_c) to elucidate the temperature effect. We utilized force-volume (FV) mode for SMFS, which enables the measurement of single-chain information while simultaneously obtaining information about the surface morphology of the crystal. By comparing the morphological changes before and after SMFS, we can locate the position of the stretched single chain and observe the morphological changes after the single chain is stretched. Combined with the force-extension curves of a single polymer chain, we can infer information about the 3D structure of the molecular chains and the interchain structure in the crystal. Morphological and molecular-level structural data show that intermediate structures are more likely to form at low temperatures, while adjacent reentry structures form at high temperatures. Interestingly, temperature does not affect the degree of chain folding, i.e., the number of adjacent reentry folds. However, the aggregation structures formed by chain folding differ due to changes in surface free energy. This provides a new method for studying the structural changes of a single chain during polymer crystallization.

Self-healing polymers have garnered significant attention owing to their long service lives and high safety in harsh environments. Given the increasing need for environmentally sustainable materials with broader application avenues, the fabrication of self-healing materials exhibiting highly favorable mechanical properties and recyclability has gained considerable significance in recent years. However, such materials still remain limited in existence. Therefore, in this study, we fabricate recyclable self-healing polymer material by incorporating rigid polycarbonate segments featuring various molecular weights and hierarchical H─bonding interactions. As the results, the polycarbonate segments improve the mechanical properties of the polymers, and the hierarchical H─bonds imparts effective self-healing capabilities and further reinforces the mechanical performance. Specifically, the as-synthesized polymers achieve a tensile strength exceeding 68 MPa and demonstrate a self-healing efficiency of 70% after being subjected to a 70°C environment for 24 h. The results also indicate that high-value polycarbonate diol (PCDL) monomers can be effectively recycled from polymers using deep eutectic solvents. Ultimately, the combination of high performance, chemical and physical recyclability, and self-healing properties positions the fabricated polymers as a promising candidate for sustainable engineering applications.

Membrane fouling has been a persistent challenge in the protein ultrafiltration process. Stepwise interfacial complexation demonstrates an effective strategy to improve anti-fouling property. The poly(acrylic acid)/poly(2-ethyl-2-oxazoline) (PAA/PEOX) multilayer exhibits excellent anti-fouling property, yet only applied in acid environment (pH < 5). Herein, the amine-crosslinked (PAA-co-NH₂/PEOX-co-NH₂)_n membranes are fabricated, which show broadened pH stability (pH 2∼12) upon FT-IR characterization. In addition, the static BSA adsorption and dynamic cyclic filtration results confirm the superior anti-fouling property of the (PAA-co-NH₂/PEOX-co-NH₂)_n membranes, displaying 30%-57% decline in static BSA adsorption and 54%-76% decrease in total fouling ratio compared to PVDF. It contributes to their enhanced hydrophilicity (53°), smoother surface (22.3 nm), and increased negative surface charge (-22.5 mV) compared to PVDF (89°, 33.8 nm, and -11.4 mV). Benefiting from the chain conformation transformation of PAA-co-NH₂, membranes possess remarkable pH-triggered cleaning ability, leading to a ∼100% recovery in water flux. Moreover, the membranes exhibit superior water flux (227 L·m^-2·h^-1) and BSA retention (97%) compared to PVDF (retention, 63%). This work provides a facile and effective strategy to develop polymer complex-based coatings with pH-response and anti-fouling property to improve protein separation performance for ultrafiltration membranes.

This study focuses on polycaprolactone (PCL)-based semi-crystalline polymer networks, examining how their physicochemical, thermal, mechanical, and shape-memory properties depend on two key photo-crosslinking parameters–crosslinking temperature and UV light intensity–as well as on the fabrication method (2D vs. 3D), ultimately providing practical guidelines for the optimal design of structures with tailored performance. More details can be found in the Research Article by Lorenzo Bonetti and co-workers (DOI: marc.202500631).

Epoxy resins exhibit variations in their polymerization mechanisms, curing temperatures, curing times, and mechanical properties of the cured products depending on the curing agent used. Elucidating the mechanism of the reaction between the curing agent and epoxy groups is important. However, the polymerization mechanism of epoxy groups induced by tertiary amines remains unclear, particularly regarding the relationship between the properties of the amines and their polymerization ability based on their nucleophilicity because the number of tertiary amines investigated is limited. Herein, we demonstrate that nucleophilicity and leaving ability of the base, rather than basicity, are the critical factors controlling reactivity in the epoxy polymerization when using tertiary amines. Quinuclidine, which combines these important properties, can polymerize epoxy monomers significantly faster than the conventionally used N,N-dimethylbenzylamine. This study establishes criteria for the selection of amines for the curing of epoxy resins using tertiary amines and provides guidelines for developing new curing agents based on molecular design.

Herein, a novel approach to create macroscale lower critical solution temperature (LCST) thermoresponsive hydrogels in a controlled manner using living cationic polymerization and a subsequent radical reaction is presented. By using a crosslinker capable of orthogonal reactions, 4-(vinyloxy)butyl methacrylate (VBM), which contains both vinyl ether and methacrylate moieties that react via cationic polymerization and radical reactions respectively, tremendous control over both the synthesis of the polymer structure as well as the hydrogel structure and its macroscale size and shape, by a post-polymerization UV light initiated radical reaction, is achieved. A series of random copolymers with the orthogonal crosslinker VBM, and LCST thermoresponsive monomers, methoxy ethyl vinyl ether (MOVE) or ethoxy ethyl vinyl ether (EOVE) or both, are synthesized. Introduction of VBM, even in small quantities, causes significant decreases in the observed phase transition temperatures for these thermoresponsive polymers and enables tuning of these temperatures. The hydrogels created from these polymers also exhibit clear LCST behavior with phase transition temperatures that are generally higher than for their corresponding polymers and over a wider temperature range. The use of this orthogonal reaction approach allows for control and design over both the polymer structure as well as that of the hydrogel.