Macromolecular Rapid Communications最新文献

Isotactic polybutene-1 (PB-1) shows peculiar crystallization behavior during crystallization from the melt, the metastable form II is always obtained. During aging at room temperature, the metastable crystals further undergo a solid-solid transition into the stable form I with a corresponding change in volume. Therefore, direct formation of the stable crystalline form I' in PB-1 has attracted significant attention in research. In this work, we report a molar mass (M_w) dependency of polymorph selection in PB-1 under compressed carbon dioxide (CO₂). PB-1 with a lower M_w exhibited a larger fraction of form II than the higher M_w PB-1 at the same CO₂ pressure, and the former required a higher pressure to completely suppress the formation of form II. It was shown that differences in chain morphologies in the formed crystals played a decisive role in polymorph selection. PB-1 with a lower M_w crystallized into form II with chain-extended crystals, whereas PB-1 with a higher M_w crystallized into form II with folded-chain crystals. A lower nucleation free energy barrier was expected in the former than in the latter, weakening the suppression of form II in a lower M_w PB-1 under compressed CO₂.

Shape memory polymers and their composites are promising smart materials for a wide range of applications associated with smart material-based actuators. Carbon fiber-reinforced shape memory epoxy composites can enable electroactive shape recovery via Joule heating, offering precise, remote-controlled actuation. However, predicting time-dependent recovery behavior across varying current levels remains challenging due to limited experimental data. This study presents an overfitting-aware machine learning framework for predicting shape recovery angles of the shape memory epoxy composites activated by Joule heating as a function of time and applied current. Four regression algorithms: Random Forest (RF), Support Vector Regression (SVR), Regularized Polynomial, and Gaussian Process Regression (GPR) are considered for constructing the shape memory recovery angle prediction algorithm. In the models, overfitting constraints are integrated into Bayesian hyperparameter optimization using a hybrid objective function that penalizes excessive generalization gaps. Stratified fivefold cross-validation ensures balanced current distribution across folds. Results demonstrate that kernel-based methods outperform tree ensembles: SVR achieves the highest accuracy with controlled generalization (R² = 0.944) while RF exhibits limited effectiveness (R² = 0.842), confirming tree-based methods are less suitable for small, smooth datasets. SVR provides optimal accuracy-generalization balance for reliable engineering predictions.

We report the first discovery of polymer single crystal whiskers with a fundamentally unprecedented architecture: prismatic poly(p-benzamide) (PBA) whiskers with practical dimensions (∼17 µm length, ∼1 µm width, ∼0.5 µm thickness). Within these whiskers, polymer chains are oriented perpendicular to the long axis while maintaining high crystallinity. This morphology diverges from conventional lamellar structures, representing a new class of staggered polymer crystalline architecture where adjacent chains interpenetrate without layered periodicity. The configuration exposes chain ends at whisker surfaces, significantly enhancing dispersibility in organic solvents and polymer matrices due to the high-energy surface. Composites incorporating these whiskers exhibit uniform microstructures, exceptional thermal stability, and high modulus. PBA whiskers offer a lightweight, organic alternative to traditional inorganic fillers. These findings not only introduce a sustainable strategy but also redefine structural design principles in polymer crystallography for high-performance materials via self-organization pathways.

Organic electrochemical transistors (OECTs) offer unique advantages for bioelectronic and neuromorphic applications. The development of n-type enhancement-mode devices is essential for creating complementary circuits and low-power, bidirectional bioelectronic platforms. However, progress in this area has been hindered by the challenges associated with processing suitable n-type polymers. Here, we present a nanoparticle-based processing strategy for the ladder polymer poly(benzimidazobenzophenanthroline) (BBL). This n-type mixed conductor is soluble only in strong acids, which hinders straightforward fabrication. BBL nanoparticles are obtained by reprecipitation with an anionic surfactant, and systematic analysis reveals a particle-number-controlled scaling law, in which surfactant concentration and the polymer-to-surfactant ratio govern stabilization. Films prepared from these dispersions further underscore the importance of nanoparticle assembly: spray-coating yields dense, interconnected networks with markedly higher electrochemical activity than the porous films obtained by the filtration-transfer method. The spray-coated BBL films operate in enhancement mode, exhibiting efficient switching in the subthreshold regime while remaining non-conductive at zero gate bias. This work establishes a scalable route to n-type enhancement-mode OECTs, thereby broadening the foundation for next-generation bioelectronic and neuromorphic systems.

Precise spatial confinement of enzymes at oil-water interfaces offers an elegant strategy to enhance biphasic catalysis yet achieving robust and recyclable interfacial assemblies remains challenging. Here, we introduce an amphiphilic polymeric Janus particle platform that enables lipases to preferentially localize at interfaces, thereby achieving efficient Pickering interfacial catalysis (PIC). Crosslinked poly(hydroxypropyl methacrylate) colloids bearing surface carboxylic acid groups were synthesized via RAFT-mediated heterogeneous copolymerization and further transformed into snowman-shaped Janus particles through seeded emulsion polymerization. The resulting amphiphilic Janus colloids possess distinct hydrophilic-hydrophobic domains that facilitate both enzyme anchoring and emulsion stabilization. Candida rugosa lipase (CRL) immobilized on these particles exhibited strong interfacial activity, achieving enhanced catalytic efficiency, thermal stability, and recyclability compared to free CRL. The present work suggests that enzyme immobilization on Janus colloids is a promising approach to advance next-generation PIC.

Poly(ylide)s - Exploring a vast chemical space: In the Research Article (DOI: 10.1002/marc.202500641), Patrick Théato, Kevin Neumann, and co-workers introduce poly(iminopyridinium ylide) as a stable, charge-neutral and hydrophilic polymer that resists nonspecific biomolecular interactions and stabilizes proteins, positioning it as a promising material in medicine.

We distinguish two rheological routes to the liquid-solid transition (LST) in soft materials by tracking the linear viscoelastic spectrum under small-amplitude oscillatory shear. Type I (dynamical arrest) shows the growth of a low-frequency elastic plateau without a reversal in the loss-tangent trend; Type II (percolation with criticality) features scale-free spectra at a well-defined time and a reversal in the loss-tangent trend. In synthetic hectorite suspensions spanning broad clay and salt concentrations, freshly prepared samples consistently follow Type II. After aging and pre-shear, the pathway becomes history-dependent: a map in composition-shear space reveals a boundary where high clay concentrations undergo Type I only, whereas lower clay concentrations evolve from Type I to Type II; increasing pre-shear rate shifts this boundary to higher clay content. A unified mechanism links these routes to aggregation kinetics: early particle-cluster growth yields peaked cluster-size distributions and Type I arrest; later depletion-enhanced cluster-cluster aggregation produces heavy-tailed distributions and Type II percolation. These results explain why "shear rejuvenation" does not restore the fresh state and provide a spectrum-based framework relevant to colloids and polymer systems undergoing physical or chemical gelation.