Macromolecular Rapid Communications最新文献

Over the last two decades, there has been substantial development in the manufacturing of nano- and micro- tubes and wires as building blocks for electronic devices, such as field-effect transistors, to complement the conventional semiconductor transistors in electronic circuits. Previous attempts to improve device performance through the development of new materials have focused mostly on carbon or metal oxide-based semiconducting materials. Here, we report a flexible conducting polymer micro-wire grown from the vapor phase via an oxidative polymerization route. Electrical measurements show that the single micro-wires have relatively high conductivity and non-linear electrical characteristics. In addition, we demonstrate the fabrication of a flexible polythiophene micro-wire organic electrochemical transistor, in which the channel and gate are made of single micro-wires. These devices are fully compatible with conventional fabrication processes and operate in the sub-volt regime, and have the potential to be scaled to larger multi-micro-wire architectures and circuits. This study demonstrates the concept of self-assembly of organic molecules and simultaneous polymerization to generate complex, ordered, and functional structures resembling polymerized Bechgaard salts.

The semi-aromatic co-polyamide PA6T/66, known for its high thermal stability, low moisture absorption, and promising melt-processability, is generally regarded as a typical eutectic copolymer. However, there is no adequate understanding of the eutectic behavior under the coupled field of temperature and pressure that widely exists in melt processing. In this work, a series of PA6T/66 samples crystallized under coupled temperature-pressure fields were investigated using a combination of differential scanning calorimetry and in situ wide/small angle X-ray scattering. Unexpected multi-stage melting indicated comonomer partition across cocrystal domains, providing evidence of pseudo-eutectic behavior. Under coupled temperature-pressure fields, segments with long 6T sequences aggregated and formed cocrystals at a higher temperature, while the excluded segments with shorter 6T sequences subsequently formed cocrystals at a lower temperature. This led to the generation of cocrystals with different compositions of 6T repeat units. This work clarifies the structure evolution of PA6T/66 under coupled temperature-pressure fields and provides an efficient strategy for the performance improvement of semi-aromatic polyamide copolymer products.

Modulating biomaterial properties using light holds great promise for biomedical applications, such as drug delivery, as it is non-invasive and offers both spatial and temporal control. Visible light is particularly salient for stimulation of cell-interfacing materials, as it is cyto-compatible; however, this limits the number of photoswitches appropriate for these applications. In this work, we use donor-acceptor Stenhouse adduct (DASA) functionalized polymers comprising poly(ethylene glycol)-b-poly(hexyl methacrylate) to make visible light-responsive polymersomes, and use these to encapsulate a model drug cargo. We demonstrate that release of the model cargo can be triggered using visible light when the polymersomes are loaded into poly(ethylene glycol) hydrogels. Moreover, ON/OFF switchable cargo release was demonstrated by modulating the light stimulation of the hydrogel. We envisage this could be used to dynamically modulate hydrogel properties in clinically relevant applications for controlled delivery of small molecule therapeutic agents, such as advanced in vitro tissue models and implantable drug-eluting scaffolds.

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.