Chinese Journal of Polymer Science最新文献

In this study, dynamic selenonium salts were incorporated into a polyurethane (PU) matrix to develop transparent, healable and antibacterial coatings. Through systematic formulation optimization, optically clear materials with excellent room-temperature hardness were obtained. Fine-tuning the selenonium content established a synergy between antibacterial performance and network dynamics, as evidenced by vitrimer-like rheological behavior at elevated temperatures. Consequently, the coatings exhibited outstanding reprocessability while maintaining high transparency and structural stability after prolonged saltwater exposure. These integrated features underscore the potential of the developed cationic PU coatings as robust, multifunctional materials for electronic device protection and marine antifouling, combining long-term transparency, recyclability, and antibacterial durability.

Shear banding in entangled polymer melts remains a fundamental yet unresolved phenomenon in nonlinear polymer rheology. Here, we perform molecular dynamics simulations of bidisperse entangled melts—comprising equal numbers of chains with lengths N=200 and N=400—to uncover the structural origins and dynamic evolution of shear banding. This bidisperse system amplifies spatial heterogeneities in the entanglement network and facilitates direct comparison with monodisperse melts of N=300, revealing quantitatively consistent steady-state shear stress versus shear rate responses. Notably, a pronounced stress plateau spanning over an order of magnitude in shear rate is observed, within which shear banding emerges reproducibly across independent simulations, as confirmed by systematic velocity profile and interface position analyses. Our findings challenge the prevailing notion that shear banding arises solely from dynamic flow instabilities. Instead, we establish a microstructure-driven framework, demonstrating that shear band nucleation is governed by pre-existing structural heterogeneities—specifically, localized weakening of the entanglement network at short-chain-enriched “soft spots”, indicative of a robust microstructural memory effect. During shear start-up, short chains preferentially disentangle and migrate along the shear direction; beyond a critical strain, long chains retract and redistribute away from the fast shear band center to minimize elastic energy. This chain-length-dependent migration dynamically enriches the shear band in short chains, stabilizing its structure and revealing a molecular mechanism that links entanglement heterogeneity to macroscopic flow localization. By bridging molecular-scale structural features with nonlinear rheological responses, this work offers a complementary perspective to classical tube and convective constraint release (CCR) models, highlighting the critical interplay between microstructural heterogeneity and chain migration in the onset and persistence of shear banding.

Temperature-sensitive random copolymerized nanohydrogels were prepared via a one-pot polymerization method using N-isopropylacrylamide (NIPAM) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as raw materials. Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) analyses revealed the partially crystallized porous nanostructure of the gels, which is consistent with the characteristics of porous nanohydrogel materials. The low-molecular-weight polymers exhibited enhancement and sharpening of the end group peaks in Fourier-transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance hydrogen (¹H-NMR) spectra due to the high proportion of small molecules or low-molecular-weight chain segments. In turn, the high-molecular-weight polymers showed pronounced peaks in the main chain segments because of the long-chain effect. Hygroscopicity increased with the molecular weight of the selected polymers, but was inhibited by temperatures below the lower critical solution temperature (LCST). Meanwhile, moisture desorption was faster in low-molecular-weight samples, and the overall moisture desorption rate rose above the LCST value. According to the kinetic analysis, the moisture absorption process conformed to the quasi-primary or quasi-secondary kinetic model, whereas the moisture desorption followed the quasi-secondary model. Moisture cycling experiments showed that the material maintained stable moisture absorption and desorption performance after several cycles, which is essential for long-term cycling.

4D-printable shape memory polymers (SMPs) hold great promise for fabricating shape morphing biomedical devices, but most existing printed polymers either require harsh activation conditions or lack sufficient mechanical strength for vascular implantation. Here, we report a dual-stimuli-responsive shape memory polymer system enhanced by acrylated Pluronic F127 (PF127-DA) micelles, which can be fabricated using digital light processing (DLP) based 3D printing. The PF127-DA based nanoscale micelles, which are formed via self-assembly in the hydrogel ink for 3D printing, act as crosslinkers to improve mechanical strength, fatigue resistance and elastic recovery. After drying the printed hydrogel, the obtained SMPs exhibit excellent shape recovery behaviour under mild physiological conditions—specifically body temperature (37 °C) and aqueous swelling—resulting in recovery stress up to about 150 kPa. This swelling-assisted actuation enables effective radial support, making the printed constructs suitable for vascular use. In vitro cytocompatibility assays with NIH/3T3 fibroblasts confirmed the suitable biocompatibility. Furthermore, the self-expanding behavior of the printed stents was validated in an occluded vessel model under physiological conditions. These results demonstrate the feasibility of 4D printed micelle-enhanced SMP for patient-specific, minimally invasive vascular stents and other soft implantable devices requiring high recovery force under physiological stimulation.

This work proposes a bioinspired hierarchical actuation strategy based on liquid crystal elastomers (LCEs), inspired by the helical topological dynamic adaptation mechanism of plant tendrils, to overcome the bottleneck of precise anisotropic control in LCEs. Mechanically pre-programmed hierarchical LCE structures responsive to near-infrared (NIR) light were fabricated: the oriented constrained actuator achieves asymmetric contraction under NIR irradiation, enabling reversible switching between helix and planar morphologies with multi-terrain grasping capability; the biomimetic vine-like helical actuator, composed of Ag nanowire photothermal layers combined with helical LCE, utilizes temperature-gradient-induced phase transition wave propagation to achieve NIR-controlled climbing motion; the Möbius topology actuator realizes reversible deformation or self-locking states by tuning the twist angle (180°/360°); based on these, a bioinspired koala-like concentric soft robot was constructed, successfully demonstrating tree trunk climbing. This study reveals that artificial helical stretching significantly enhances the molecular chain orientation of LCEs (surpassing uniaxial stretching), reaching up to 1000% pre-strain, and the AgNWs/LCE/PI (Polyimide) tri-layer structure achieves efficient photothermal-mechanical energy conversion via localized surface plasmon resonance (LSPR). This study provides a new paradigm for soft robotics material design and topological programming, demonstrating the potential for remote operation and adaptive grasping.

Ultrasound (US), as an efficient and non-invasive trigger, has been extensively explored in drug delivery and has many advantages, such as deep penetration, low invasiveness, and high biochemical precision. These advantages demonstrate the immense clinical potential of ultrasound. This study aimed to provide a comprehensive analysis of ultrasound-induced shear forces that exhibit covalent/non-covalent bond cleavage and reactive oxygen species (ROS)-mediated remote control of nanocarriers. By doing so, we can gain a deeper understanding of the vital role, significant advantages, and untapped potential of ultrasound in molecular-level drug activation. Furthermore, clinical translation faces challenges such as the low drug-loading capacity of polymer chains, frequency compatibility between ultrasound parameters and biological systems, insufficient ROS generation, and biocompatibility of current sonosensitizers. To solve these problems, ultrasound mechanochemistry has emerged as a versatile therapeutic modality to promote the development of medical treatments.

To address the poor mechanical properties of polydimethylsiloxane (PDMS) and enhance the understanding of the reinforcement mechanisms of aerogel network structures in rubber matrices, this study reinforced PDMS using an ordered interconnected three-dimensional montmorillonite (MMT) aerogel network. The average pore diameter of the aerogels was successfully reduced from 11.53 µm to 2.51 µm by adjusting the ratio of poly(vinyl alcohol) (PVA) to MMT via directional freezing. Changes in the aerogel network were observed in field emission scanning electron microscope (FESEM) images. After vacuum impregnation, the aerogel network structure of the composites was observed using FESEM. Tensile tests indicated that as the pore diameter decreased, the elongation at break of the composites first increased to a peak of 329.61% before decreasing, while the tensile strength and Young’s modulus continuously increased to their maximum values of 6.29 MPa and 24.67 MPa, respectively. Meanwhile, FESEM images of the tensile cracks and fracture surfaces showed that with a reduction in aerogel pore diameter, the degrees of crack deflection and interfacial debonding increased, presenting a rougher fracture surface. These phenomena enable the composites to dissipate substantial energy during tension, thus effectively improving the mechanical strength of the composites. The present work elucidates the bearing of ordered three-dimensional aerogel network structures on the performance of rubber matrices and provides crucial theoretical insights and technical guidance for the creation and optimization of high-performance PDMS-based composites.

Understanding the thermodynamic behavior of complex fluids in confined environments is critical for various industrial and natural processes including but not limited to polymer flooding enhanced oil recovery (EOR). In this work, we develop Atif-V2.0, an extended classical density functional theory (cDFT) framework that integrates the interfacial statistical associating fluid theory (iSAFT) to model multicomponent associating fluids composed of water-soluble polymers, alkanes, and water. Building on the original theoretical framework of Atif for modeling nanoconfined inhomogeneous fluids, Atif-V2.0 embeds explicit solvent and captures additional physical interactions - hydrogen bonding, which are critical in associating fluid systems. The other key feature of Atif-V2.0 is its ability to account for polymer topology. We demonstrate its capability by predicting the equilibrium structure and thermodynamic behavior of branched hydrolyzed polyacrylamide solutions near hard walls with various branching topologies, which provides a robust theoretical tool for the rational design of EOR polymers.

Knotting occurs in polymers and affects polymer properties. Physical understanding of polymer knots is limited due to the complex conformational space of knotted structures. The knotting problem can be handled by the tube model, which assumes that knotted polymer segments are confined in a virtual tube. Recently, we quantified this virtual tube using a computational algorithm. The algorithm was limited to the simplest knot: 3₁ knot. It remains unclear how the tube model and computational algorithm are applied to more complex knots. In this work, we apply the tube model to 4₁, 5₁, and 5₂ knots, resulting in several findings. First, the computational algorithm developed for 3₁ knot cannot be directly applied to 4₁ knot. After modifying the algorithm, we quantify the tubes for 4₁ knot. Second, we find that, for all four knot types, the knotcore region have less average bending energy density than unknotted regions when the chain bending stiffness is small. This counterintuitive result is explained by the tube model. Third, for all four knot types, polymer segments at the boundaries of knot cores adopt nearly straight conformations (almost zero bending) and exhibit lower local bending compared to other knot-core regions and unknotting regions. This local behavior is also consistent with prediction from the tube model. This counterintuitive result is also explained by the tube model. Fourth, for all four knot types, when a polymer has non-uniform bending stiffness, a knot prefers certain chain positions such that the knot boundary locates at one stiff segment. Overall, our work paves the way for applying the tube model to complex polymer knots and obtains many common results for different knot types, which can be useful in understanding many knotting systems, such as DNA knots in vivo.