最新刊期
卷 57 ， 期 8 ， 2026
- 摘要：Biodegradable polyesters are promising alternatives to conventional petroleum-based plastics owing to their favorable bio-based origin, biocompatibility, and degradability. Achieving precise control over the microstructural sequence structure distribution of copolyesters during the ring-opening polymerization (ROP) of cyclic esters is a critical scientific challenge. To address this issue, this feature article summarizes recent advances in the sequence control of alternating copolyesters, with an emphasis on two representative strategies: (i) the regioselective ROP of asymmetric cyclic diesters, elucidating the regulatory mechanisms governing selective ester bond cleavage via electronic and steric effects, and (ii) the stereoselective ROP of chiral cyclic esters, the roles of syndioselective polymerization in achieving dyad sequence control, and heteroselective copolymerization in achieving triad and tetrad sequence control are summarized. Furthermore, the critical role of catalysts/initiators in balancing monomer reactivity, enhancing the regioselectivity and stereoselectivity of the polymerization system, and tailoring the polyester topology is discussed. It was further demonstrated that precise sequence control significantly improved the thermal properties, mechanical performance, degradation behavior, and drug release characteristics of copolyesters. Finally, future directions in this field are discussed.关键词：Sequence control;Alternating copolyesters;Ring-opening polymerization;Regioselectivity;Stereoselectivity391|70|0更新时间：2026-07-30
Feature Article
- 摘要：Dissipative particle dynamics (DPD) simulations were employed to investigate the self-assembly behavior of amphiphilic block copolymers with dynamic covalent bonds. The results showed that in the presence of dynamic covalent bonds, multicompartment vesicles, vesicles, large compound micelles, and spherical micelles can be obtained by tuning the hydrophobic interaction and the interaction between blocks. Hydrophobic interactions served as the primary driving force for self-assembly, whereas the interaction between blocks regulated the interfacial curvature, thereby further controlling the aggregate morphology. With increasing repulsion between the blocks, the aggregate morphology underwent a sequential transition from large compound micelles to multicompartment vesicles, vesicles, and micelles. From a kinetic perspective, the system concentration exerted a non-monotonic effect on the bond fraction of the dynamic bonds. At low concentrations, the reaction was diffusion-controlled, and the bond fraction increased with increasing concentration. When the concentration further increased, the enhanced excluded-volume effects and spatial confinement suppressed subsequent bond formation, resulting in an optimal concentration window for bond formation. In addition, a comparison of the assembly pathways between the free-chain and pre-connected block models revealed that the initial topological connectivity significantly affects the assembly evolution process. Compared with the free-chain system, the region for single-compartment vesicle formation was markedly enlarged in the preconnected block system. These results provide a theoretical basis for the morphological design of polymer aggregates regulated by dynamic covalent bonds.关键词：Block copolymers;Amphiphilicity;Dynamic covalent bonds;Self-assembly;Dissipative particle dynamics (DPD)294|46|0更新时间：2026-07-30
- 摘要：In view of the problems of catheter-related thrombosis and catheter-related bloodstream infections arising from the clinical application of central venous catheters (CVCs), inspired by the biomimetic adhesion mechanism of mussels, this study constructed an amino-rich polydopamine-hexamethylenediamine active substrate on the surface of medical polyurethane via physical deposition. Subsequently, fluorinated compounds and zwitterionic compounds were respectively grafted through mild amidation and Michael addition reactions, thereby successfully developing two types of coatings with hydrophobic and hydrophilic properties that possess dual anti-thrombotic and antibacterial functions. In vitro evaluations demonstrated that both coatings could significantly inhibit the adhesion of proteins, platelets and bacteria, and effectively prevent thrombus formation. Ex vivo arteriovenous shunt and subcutaneous infection models further validate their outstanding in vivo anti-thrombotic and anti-infective performance. Furthermore, the coatings exhibited favorable biocompatibility. The coating preparation method established in this study is simple and universally applicable, providing a novel strategy with promising clinical transformation potential for the functional modification of blood-contacting devices such as CVCs.关键词：Central venous catheter;Mussel-inspired;Polydopamine coating;Antithrombotic;Antibacterial278|144|0更新时间：2026-07-30
- 摘要：A series of binary catalytic systems composed of metal porphyrin complexes and organic bases were designed and developed to catalyze the pyrolysis of the representative CO2-based polycarbonate, polycyclohexene carbonate (PCHC), using poly(ethylene glycol) 500 (PEG 500) as the reaction solvent. This strateg enabled the highly selective recovery of cyclohexene oxide (CHO), the corresponding epoxide monomer, from PCHC depolymerization Systematic catalyst screening was performed to evaluate the influence of the metal center, axial anion, and organic base on the catalytic activity and product selectivity. The results showed that the catalytic system of aluminum tetraphenylporphyrin complex with trifluoroacetate as the axial ion and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) exhibited the highest activity. Under optimized reaction conditions, namely a temperature TBD/PCHC=1/2/1000, PCHC was completely depolymerized within 1 h, affording CHO with a selectivity as high as 97%. Mechanistic studies confirmed that PCHC depolymerized through a combination of random chain scission and chain-end back-biting, through the intermediate trans-cyclohexene carbonate (trans-CHC), which was further decomposed to form CHO monomer. These results demonstrate that the metal porphyrin/organic base binary catalytic system provides an efficient approach for the selective chemical recycling of CO2-based polycarbonates into value-added monomers.关键词：Epoxide;Poly(cyclohexene carbonate);Chemical recycling;Metal porphyrin;Depolymerization311|53|0更新时间：2026-07-30
- 摘要：Developing chemically recyclable thermoplastic elastomers (TPEs) from bio-renewable feedstocks to replace widely used polystyrene-based TPEs is a promising strategy for addressing the end-of-life issue of plastics. In this study, a series of triblock copolymers was successfully prepared by the sequential ring-opening copolymerization of bio-based γ-methyl-ε-caprolactone and 6-oxabicyclo[3.2.1]octan-7-one in the presence of a binary catalytic system composed of an organobase (tBu-P1) and urea (U1). The obtained copolymers were carefully examined using 1H-, 13C-, and 2D DOSY-NMR spectra. All the triblock copolymers had a 5% weight-loss temperature above 342 ℃, indicating their excellent thermal stability. The microphase separation between the soft and hard segments was confirmed by differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) measurements. The thermal and mechanical properties of these triblock copolymers can be adjusted by changing the molar fraction of the hard segment (Fhard) and molecular weight (Mn). The tensile strength of these copolymers increased with increasing Fhard and molecular weight. Specifically, a triblock copolymer (TPE-4) with a Fhard of 43% and Mn of 130 kDa exhibited good thermoplastic elastomer properties, with a high tensile strength of 27.5 MPa and an elongation at break of 1100%. Meanwhile, TPE-4 also exhibited excellent elastic recovery of 78.2%, good resilience of 58.2%, and low residual strain of 13.7%. Furthermore, the prepared triblock copolymers can be depolymerized in bulk at 180 ℃ using sodium hydroxide as the catalyst. The monomers can be easily recovered by vacuum distillation, with a yield of up to 85%. The recovered monomers can be re-polymerized to afford triblock copolymers with molecular weights and mechanical properties comparable to those of the original TPE material. This study offers a simple strategy for preparing high-performance, closed-loop recyclable TPEs from bio-renewable feedstocks.关键词：Thermoplastic elastomer;Triblock copolymer;Ring-opening polymerization;Closed-loop Recycling;Aliphatic polyester259|9|0更新时间：2026-07-30
- 摘要：Persistent hypoxia is a critical factor limiting tissue regeneration during chronic wound healing, highlighting the importance of developing polymer-based systems capable of controlled oxygen delivery. In this work, we constructed a reaction-transport coupled oxygen-generating system based on multi-interface regulation by a polydimethylsiloxane (PDMS) membrane and an alginate hydrogel. Through a multilayer structural design, the system spatially integrated hydrogen peroxide (H2O2) storage, transmembrane diffusion, interfacial catalysis, and oxygen transport into a hierarchical pathway, enabling coordinated control over reaction and mass transport processes. The PDMS membrane served as a key transport-regulating interface, where membrane thickness governs the flux of H2O2, converting its intrinsically rapid decomposition into a diffusion-controlled and stabilized reaction process. The MnO2 catalytic layer provided a solid-gas interfacial reaction environment, while the hydrogel interface facilitated the conversion of oxygen from gaseous to dissolved form and promotes its transport into surrounding tissue. Experimental results demonstrated that the system enabled sustained and stable dissolved oxygen output, significantly improving cell viability under hypoxic conditions. In a diabetic wound model, the system markedly accelerated wound healing, accompanied by enhanced collagen deposition and neovascularization. This work reveals a materials design strategy based on multi-interface coordination of reaction and transport processes, providing new insights into the development of functional polymer systems for hypoxia-related diseases.关键词：Polydimethylsiloxane;Hydrogel dressing;Dissolved oxygen;Chronic wound231|47|0更新时间：2026-07-30
- 摘要：A heterogeneous titanium catalyst (Ti-dMMAO/SiO2) was prepared by loading the titanium complex [t-BuNSiMe2Flu]TiMe2 onto SiO2-supported modified methylalumoxane (dMMAO/SiO2). The resulting Ti-dMMAO/SiO2 was used to catalyse the polymerization of α-olefins. The results indicated that the activity for the homopolymerization of 1-hexene increased with an increase in the Al/Ti molar ratio; when the Al/Ti molar ratio was 1000, the activity reaches a maximum of 1.34×106 g·mol-1·h-1; The weight-average molecular weight (Mw) of the resulting polymer first increased and then decreased with an increase in the Al/Ti molar ratio; when the Al/Ti molar ratio was 400, the Mw reached a maximum of 0.90×106 g·mol-1. Although the polymerization activity decreased somewhat with increasing side-chain length of the α-olefins, the TOF value for the polymerization of 1-octadecene still reached 104 min-1, whilst the resulting poly(1-octadecene) retained a high molecular weight (0.90×106 g·mol-1). The resulting poly(1-dodecene) and poly(1-octadecene) crystallized due to their long side chains, with melting points (Tm) of -24 and 43 ℃, respectively. To improve the solubility of this class of polymers in oil, 1-octadecene was copolymerized with 1-octene in a random copolymerization process. The copolymerization results indicated that the Ti-dMMAO/SiO2 catalytic system yielded high-molecular-weight random copolymers whilst maintaining high activity and appearance can also be improved.关键词：Fluorenylamidodimethyl-titanium complexes;Heterogeneous catalysts;α-Olefins;Coordination polymerization245|22|0更新时间：2026-07-30
- 摘要：The tendency of poly(acrylic acid) (PAA) and poly(ethylene oxide) (PEO) to readily form complexes in solution is one of the key factors limiting the fabrication of PEO/PAA electrospun membranes. In this study, PEO/PAA porous fiber membranes were fabricated via electrospinning using a solvent mixture of N,N-dimethylformamide and acetone at a volume ratio of 7:3. It was found that both the polymer concentration in the spinning solution and the PEO-to-PAA mass ratio exerted significant influences on the structure and properties of the porous fiber membranes. The membrane exhibited the most uniform fibre morphology under the mass fraction of 6 wt%. Moreover, the membrane showed shape-memory behaviour and humidity responsiveness at a mass ratio of 5:1. After experiencing 40% tensile deformation, the membrane recovered to its original shape when heating at 60 ℃. Once the membrane placed on human hand, it could deform rapidly in a direction opposite to the hand. Furthermore, the membrane exhibited the optimal mechanical performance with an elongation at break up to 882% when the mass ratio was 1:1. The liquid metal was blade-coated onto the membrane surface for assembling a capacitive wearable sensor, which displayed excellent elastic recovery and wide-range strain response. The sensor also maintained stable and reliable sensing performance even suffered to 2000 cycles at 100% strain. Besides, the sensor could detect the finger bending, wrist motion, swallowing and chewing. This work provides a convenient electrospinning strategy and sensor preparation strategy for PEO/PAA porous fibrous membranes.关键词：Electrospinning;Sensor;Humidity response;Shape memory245|49|0更新时间：2026-07-30
- 摘要：In this study, a top-down strategy was adopted for the synthesis of poly(ester-carbonate) diols (PPCP-DL) by hydrolyzing high-molecular-weight poly(acetal-co-ester-co-carbonate) (PPCP-PAc). First, the nonmetal catalyst triethylborane (TEB)/tetrabutylammonium chloride (TBACl) was used to catalyze the quaternary copolymerization of propylene oxide (PO), carbon dioxide (CO2), phthalic anhydride (PA), and o-phthalaldehyde (OPA), affording high-molecular-weight PPCP-PAc with varied segmental compositions. Subsequently, the acetal linkages in the polymer backbone were selectively hydrolyzed under mild acidic conditions, yielding a series of low-molecular-weight PPCP-DLs with different molecular weights (1.6-3.3 kg/mol) and polyester (PE) contents (13 mol%-37 mol%). The end-group structures of PPCP-DL, confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and 19F nuclear magnetic resonance spectroscopy, revealed hydroxyl groups at both termini and a primary hydroxyl content of 43 wt%.关键词：Carbon dioxide;Poly(carbonate diol);o-Phthalaldehyde;Hydrolysis323|58|0更新时间：2026-07-30
- 摘要：Alternating azopolymers are prominent in the field of smart material design due to their distinctive self-assembly behavior, which originates from the precisely regulated solvophilic/solvophobic balance and their responsiveness to stimuli. However, the azobenzene-functionalized alternating copolymers reported thus far are predominantly synthesized through complex and time-consuming methods. In this work, novel amphiphilic alternating azopolymers, P(Azo-alt-EGm) (m=2, 3, 4, and 5), were prepared via Ugi multicomponent polymerization using commercially available monomers, including azobenzene-4,4'-dicarboxylic acid (Azo), oligo(ethylene glycol) diamines (EGm), benzaldehyde, and tert-butyl isocyanide. The polymerizations proceeded successfully, affording relatively high yields (>74%). The chemical structures, molecular weights (MWs) and MW distributions were verified through ¹H-NMR and SEC analyses. The resulting copolymers exhibited a comparable MW range, spanning from 11.9 kg/mol to 13.3 kg/mol. UV-Vis spectroscopy demonstrated that P(Azo-alt-EGm) possessed excellent photo-isomerization properties. As the value of m increased from 2 to 5, the rates of photo-induced trans-to-cis isomerization of P(Azo-alt-EGm) were (0.418±0.023), (0.461±0.011), (0.528±0.043), and (0.660±0.013) s-1, respectively. This trend was attributed to the longer EG chains providing more free space for the azobenzene groups to move. The thermal annealing-induced self-assembly behaviors of P(Azo-alt-EGm) in alcoholic solvents were systematically investigated. Firstly, P(Azo-alt-EGm) was dissolved in ethanol at 70 ℃ and maintained for 4 h, followed by incubating at 25 ℃ for 24 h. This process led to the formation of uniform polymersomes with hydrodynamic radius (Rh) ranging from 95.4 nm to 148.0 nm, depending on the increasing length of EG chains. Meanwhile, when annealed from 90 ℃ in n-propanol, P(Azo-alt-EGm) formed fusiform nanosheets, with sizes tunable according to the length of the EG chains. In both polymersomes and nanosheets, P(Azo-alt-EGm) chains are orderly arranged following a folded chain model, adopting a monolayer core-shell structure. UV-Vis spectroscopy revealed that the azobenzene groups within the assemblies had a H-aggregation. These assemblies exhibited remarkable photo-responsiveness, undergoing morphological transitions under ultraviolet/visible light irradiation. Specifically, polymersomes disintegrated into irregular aggregates under 365 nm UV light irradiation and reformed into larger polymersomes under 450 nm visible light irradiation, while fusiform nanosheets transformed into spherical micelles and subsequently into elongated "bamboo leaf"-like nanosheets. These findings indicate promising applications for P(Azo-alt-EGm) assemblies in the fields of smart materials and biomedicine.关键词：Azobenzene;Ugi reaction;Alternating copolymer;Self-assembly;photo-responsiveness153|64|0更新时间：2026-07-30
- 摘要：Diels-Alder (DA) dynamic covalent polyurethane (DAPU) elastomers are highly regarded in the field of self-healing materials due to their excellent mechanical properties and thermo-reversible healing capabilities. In this study, we employed a literature data-driven approach to investigate the structure-property relationships governing the tensile strength, elongation at break, and healing efficiency of DAPU elastomers. By systematically screening the formulation and performance data from the relevant literature, we constructed a comprehensive feature space spanning the compositional content, chemical characteristics, and structural mechanisms. Three machine learning models, namely Support Vector Regression (SVR), XGBoost, and Gaussian Process Regression (GPR), were established to quantitatively analyze these properties, yielding R2 values of 0.76, 0.66, and 0.81, respectively. The results demonstrate that the proposed feature system effectively captures the relationships between the key structural variables and properties of DAPU elastomers. Subsequent SHapley Additive exPlanations (SHAP) analysis revealed that soft-segment crystallinity and soft-segment molecular weight were the most critical parameters governing mechanical strength and healing efficiency, whereas DA functional monomer content was the primary determinant of ductility. Furthermore, complex non-monotonic correlations were identified among the three properties. This work provides a reference for understanding DAPU structure-property relationships and guiding rational-formulation design.关键词：Polyurethane;Diels-Alder dynamic bonds;Self-healing elastomer;Machine learning;Structure-property relationships;Literature data-driven305|67|0更新时间：2026-07-30
- 摘要：With the increasing power density of electronic devices, efficient thermal management is essential for improving device reliability. Polymer-based composites are promising thermal management materials because of their low density, good processability, and structural flexibility. However, the low intrinsic thermal conductivity of polymer matrices limits their heat dissipation capability. Increasing filler loading can improve heat conduction, but excessive filler content often deteriorates mechanical, electrical insulating, and processing properties. Therefore, improving filler utilization efficiency at a moderate filler fraction is important. In this work, topology optimization was used to guide the design of graphite filler structures in polydimethylsiloxane (PDMS) composites. Based on finite element simulations, a simple dumbbell-shaped graphite filler was proposed. This structure contained a continuous central heat-conduction path and expanded end regions, which could reduce through-plane thermal resistance and promote lateral heat spreading. Graphite/PDMS composites with cubic, cylindrical, frustum-like, and dumbbell-shaped fillers were fabricated by computer numerical control machining, followed by PDMS encapsulation and curing. Infrared thermal imaging and heat-flow-based tests were used to evaluate their thermal responses. Compared with conventional cylindrical and cubic fillers, the dumbbell-shaped filler produced a more uniform temperature distribution and stronger hotspot suppression. Under vacuum conditions, the hot-cold side temperature difference was reduced by 8.6 and 5.4 ℃, respectively. The dumbbell-array composite showed a heat dissipation efficiency of 0.028 W·℃⁻1, 1.47 times that of the cylindrical-array composite. This work provides an effective strategy for designing conductive filler architectures in polymer-based thermal management composites.关键词：Polymer composites;Topology optimization;Thermally conductive fillers;Thermal management428|129|0更新时间：2026-07-30
- 摘要：To address the urgent demand for low-dielectric-constant polymer dielectrics in high-frequency communication technologies, this study proposes a new strategy for modulating chain conformation through main-chain engineering to reduce the dielectric constant (Dk) and dielectric loss (Df). Distinct from conventional approaches that enhance rigidity or introduce flexible segments, we aimed to introduce controlled molecular twists while maintaining main-chain rigidity, thereby simultaneously increasing free volume and restricting dipole motion. To this end, two novel asymmetric single-quinoxaline-based difluoro monomers with different bond angles were designed and synthesized, and copolymerized with the fluorinated bisphenol 6F-BPA to successfully prepare poly(aryl ether)s, namely P6FEQA and P6FEQD, with varying degrees of main-chain twisting. For comparison, a linear polymer, P6FEQ, was synthesized using a symmetric bis-quinoxaline monomer. Systematic investigations revealed that increasing the degree of main-chain twist effectively attenuates the macroscopic polarization response by reducing packing density and strongly suppresses dipole relaxation through conformational locking. Among the obtained polymers, P6FEQD, which exhibited the highest degree of twisting, demonstrated the most outstanding dielectric performance at 15 GHz, with a Dk as low as 2.385 and a Df of only 0.00344, which was nearly an order of magnitude lower than the typical loss values of commercial poly(ether ether ketone) (PEEK) in the GHz frequency range. Notably, the monomers employed are readily synthesizable. This work provides a clear paradigm and mechanistic elucidation for achieving high-frequency dielectric performance optimization through "rigid-twist" molecular design.关键词：Poly(aryl ether);Quinoxaline;Asymmetric monomer;Low dielectric constant;Low dielectric loss277|40|0更新时间：2026-07-30
- 摘要：In this work, by adjusting the ratio of two maleimides with different structures, namely triphenyl-s-triazine-containing bismaleimide (PT-BMI) and polyamine-type maleimide (BMI950), a series of bulky low-polarity maleimide-triazine (BPT-Bs) resin systems were fabricated via stepwise curing with dicyclopentadiene-type cyanate ester (DCPDCE) initiated by di-tert-butylperoxyisopropylbenzene (BIPB). The results revealed that the stepwise curing process sequentially underwwent radical self-polymerization of maleimide, copolymerization between cyanate ester and maleimide, and self-polymerization of cyanate ester. For the BPT-Bs systems modified with combined PT-BMI and BMI950, the processing window was broadened to 89 ℃ with a minimum viscosity as low as 90 mPa·s. The 5% weight loss temperature exceeded 398 ℃, demonstrating excellent thermal stability. Copper-clad laminates (CCLs) were fabricated using glass fiber cloth-reinforced BPT-Bs resin composites. The as-prepared composites exhibited outstanding comprehensive performances: the glass transition temperature was higher than 280 ℃; the minimum coefficient of thermal expansion (CTE) along the Z-axis and X/Y-axis reached 13.5 and 6.1 ppm·K-1, respectively; the dielectric constant ranged from 3.74 to 4.08, and the dielectric loss was in the range of 0.0058-0.0090. Moreover, the flexural strength was above 521 MPa, the flexural modulus exceeded 31.1 GPa, and the peeling strength of CCLs was between 0.57 and 0.76 N·mm-1.Through the construction of bulky low-polarity rigid conjugated structures and dense interpenetrating networks, this stepwise curing strategy effectively balanced the processability, heat resistance, dimensional stability and high-frequency dielectric properties of the resin. It provides a novel insight for the development of high-performance substrate materials of copper-clad laminates applied in high-frequency IC substrates.关键词：Hierarchical curing;Bismaleimide-triazine resin;Low thermal expansion;Low dielectric136|47|0更新时间：2026-07-30
- 摘要：Lubrication and protective coatings applied to the surfaces of moving mechanisms in nuclear reactors face the dual challenges of long-life lubrication and long-term radiation stability. In this study, polysilazane (PSZ), a precursor with excellent potential for nuclear radiation resistance, was adopted as the base resin binder, and molybdenum disulfide (MoS2) was incorporated as the lubricating filler to prepare a PSZ-bonded solid lubricating coating with favorable lubricating and radiation-resistant properties. The variations in the composition, structure, mechanical properties, and tribological properties of the coating after heat treatment at different temperatures and before and after γ-ray irradiation were systematically investigated. The results show that both high-temperature heat treatment at 300 ℃ and γ-ray irradiation can promote the cross-linking and curing of the PSZ composite lubricating coating, thus significantly improving the hardness and tribological properties of the composite coating. In particular, the composite coating subjected to the combined treatment of 300 ℃ high-temperature heat treatment and γ-ray irradiation exhibited outstanding wear resistance, with an average friction coefficient of approximately 0.34 and a wear rate as low as 6.7×10-5 mm3/(N·m). The composite coating exhibited excellent tribological properties and γ-ray radiation resistance. The above research findings provide technical support and theoretical guidance for surface lubrication and protection of relevant mechanically moving components in advanced nuclear reactors under high radiation dose conditions in the future.关键词：Polysilazane;Lubricating coating;γ-ray irradiation;tribological performance876|215|0更新时间：2026-07-30
- 摘要：With the development of personal radiation protection and flexible protective equipment, gamma-ray shielding materials face higher requirements for lightweight, flexibility, and lead-free characteristics. To improve the gamma-ray shielding performance of flexible polymer-based composites, we prepared Bi2WO6 and Bi2WO6/PAN composite nanofibrous membranes with different La doping contents using polyacrylonitrile (PAN) as the matrix. Combined with microstructural characterization and performance testing, the effects of La doping on the microstructure, local electronic structure, mechanical properties, and gamma-ray shielding performance of the composite nanofibrous membranes were systematically investigate. The results showed that La doping significantly regulates the crystallization behavior of Bi2WO6 and the growth state of the inorganic phase on the fiber surface, and the relationship between La doping content and the properties of the composite nanofibrous membranes was not simply linear. Appropriate La doping improved the distribution uniformity of the inorganic phase on the fiber surface and optimizes the membrane structure, whereas excessive doping caused the formation of La-containing impurity phases and local aggregation. The 10 wt% La-doped sample exhibited the best overall performance, with mass attenuation coefficients of 4.426, 1.491, and 1.315 cm2·g-1 under three irradiation conditions, which were approximately 51.6%, 77.7%, and 151.4% higher than those of the undoped samples, respectively. This study provides a reference for the structural design and performance optimization of lightweight, flexible, and lead-free gamma-ray shielding fibrous materials.关键词：Polyacrylonitrile;Bismuth tungstate;Crystallization behavior;Polymer matrix composites;Radiation protection282|73|0更新时间：2026-07-30
- 摘要：Flexible display cover materials face the challenge of balancing high transparency, high temperature resistance, and complex service reliability. In this work, a series of colorless transparent polyimide (CPI) films were prepared by regulating the rigidity of molecular chains and free volume. It was found that as the rigidity of the molecular chains increased, the glass transition temperature (Tg) and hydrophobicity of the samples improved, while the mechanical properties showed a stronger correlation with the packing density of the molecular chains and the content of hydrogen bonds. Among them, CPI-CBDA, which contains a rigid non-conjugated cyclobutane structure, has small free volume, many hydrogen bonds, and a tightly packed molecular chain, and thus combines high transparency (average transmittance Tav in the range of 380-780 nm was 87.02%), high heat resistance, low expansion (average thermal expansion coefficient CTE in the temperature range of 50-250 ℃ was 10.52×10-6/K), and excellent mechanical properties. In terms of service evaluation, after 5×105 dynamic bends (bend radius R=2 mm), the Tav loss rate of most samples was less than 3%, and the tensile strength retention rate was higher than 85%, while the strength retention rate of commercial PET films was lower than 56%. It is worth noting that after bending, the Young's modulus of some samples increased instead, possibly due to the local cyclic strain inducing molecular chain orientation. The ultraviolet aging study shows that CPI-CBDA has the best stability. Its aging mechanism shows a staged characteristic: initially, the cyclobutane structure decomposes, then weak bonds break, while cross-linking reactions occur between molecular chains simultaneously, compensating for the degradation of mechanical properties, and its Tav retention rate after ultraviolet irradiation is as high as 97.1%, and the retention rates of tensile strength and modulus even reach 119.4% and 140.1%.关键词：Colorless and transparent polyimide;Molecular structure regulation;Dynamic bending durability;UV irradiation resistance360|63|0更新时间：2026-07-30
- 摘要：Using polycarbonate diol as the soft segment and 1,4-butanediol as the chain extender, polyurethanes with alicyclic hard segments (R-PCPU) and aliphatic hard segments (L-PCPU) were synthesized using isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI), respectively. A series of R-PCPU/L-PCPU blends (PUB) with different mass ratios were prepared via solution blending. The structure and properties of PUB were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyze (TGA), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and a universal testing machine. The results showed that, owing to the steric hindrance of the hard segments, hydrogen bonding and microphase separation were stronger in L-PCPU than in R-PCPU, and both properties in PUB increase with increasing L-PCPU content. R-PCPU primarily exhibited soft-segment crystallization (melting temperature of approximately 43.26 ℃), whereas L-PCPU exhibited hard-segment crystallization (approximately 168.66 ℃). PUB exhibited crystallization behavior in both soft and hard segments. As the L-PCPU content increased, the crystallinity of the soft segment decreased, whereas that of the hard segment increased. Benefiting from the synergistic effects of the ring-shaped and linear hard segments, PUB exhibited controllable mechanical properties, with an elongation at break (up to 900%) higher than that of R-PCPU and a tensile strength (up to 75.62 MPa) higher than that of L-PCPU. Furthermore, the synchronized crystallization behavior of the soft and hard segments endowed PUB with excellent shape memory properties, making it significantly more valuable than R-PCPU or L-PCPU. Owing to its comprehensive performance advantages, PUB showed great potential for application in the field of smart medical devices, such as orthodontic wires and self-contracting sutures. This study also provides a novel strategy for the structural design and simple preparation of shape memory polyurethane.关键词：Polyurethane blends;Hard segment structure;Hydrogen bonding;Shape memory property;Mechanical property298|51|0更新时间：2026-07-30
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