Long-chain branched polypropylene (LCBPP) exhibits superior melt strength, enhanced thermal stability, and a broader processing temperature window than conventional linear polypropylene (PP), improving its suitability for diverse industrial applications. This review focuses on recent advancements in LCBPP preparation methodologies, including macromonomer incorporation, direct copolymerization, radiation-induced branching, cross-linking techniques, and reactive melt processing, with a systematic comparison of their advantages and limitations. Characterization protocols for differentiating LCBPP from linear PP architectures were also addressed. This review outlines future research priorities, emphasizing that while China's LCBPP research is gaining momentum, substantial R&D investment remains imperative to develop high-value-added materials and strengthen China's global market competitiveness.

The harsh polar environments pose extreme challenges to the low-temperature elasticity and physical-mechanical properties of elastomer used for sealing, transportation, and mobility in scientific expedition equipment. However, traditional rubber materials face a trilemma in balancing a low glass transition temperature (T_g), high compression resistance at low temperatures, and high mechanical properties. In this study, we prepared a series of polyurethane elastomers with T_g below -50 ℃ by selecting soft segments with different structural regularities. By investigating the relationship between the molecular structure of PU and their mechanical properties as well as compression resistance at low temperatures, the mechanism of low-temperature compression resilience of PU was elucidated. The results indicated that as the regularity of its soft segments decreased, the crystallization ability of the soft segments in polyurethane weakened, leading to a reduction in tensile strength. Polyurethane with polyester-based soft segments exhibited stronger intermolecular interactions, facilitating the formation of dense hard phase microdomains, thereby enhancing tensile strength. Simultaneously, under low-temperature compression, the PU with irregular soft segments exhibited superior cold compression resistance, due to their lower degree of soft segment crystallization. Among them, PO3G-PU demonstrated a T_g of -68.2 ℃, a tensile strength of 44.0 MPa, a compression resistance coefficient of 0.632 at -40 ℃, and 0.459 at -55 ℃, all of which surpassed traditional rubber materials. This study provides new insights for the design and preparation of high-strength, low-temperature compression-resistant PU.

Thermotropic liquid crystalline polyarylates (TLCPs) are high-performance polymers with unique nematic phases and the regulation of their performance is always an issue of significant interest. The introduction of nonlinear bisphenol monomer is recognized as an effective method, however, the effects of nonlinear chemical structures and linkage on the properties of TLCPs have not been clearly understood. In this study, a series of TLCPs with various nonlinear bisphenol monomers were synthesized via one-step melt polycondensation. The melting and crystallization behaviors, thermomechanical properties, thermal stability, rheological behavior, and microscopic morphology were investigated. The results indicated that the nonlinear chemical structure disrupted the molecular chain regularity, thereby enabling effective regulation of the crystallization and rheological behavior. The presence of weak bonds in nonlinear bisphenols reduced the thermal stability of the TLCPs. Moreover, the incorporation of nonlinear bisphenol monomers led to an inhomogeneous distribution of rigid and flexible domains in certain TLCPs, which consequently resulted in a two-step decrease in the modulus.

Poly(lactic acid) (PLA) fiber membranes demonstrate considerable potential for nanoparticle filtration. However, its practical application is largely limited by weak electret performance and insufficient filtration efficiency. Consequently, modification PLA membranes to enhance the filtration performance is of significant importance. This study utilized electrospun PLA nanofiber membranes as the substrate. By a polydopamine (PDA) interfacial modification strategy, an active layer possessing strong adhesion and multiple functional groups was constructed at PLA fiber surfaces. This layer subsequently induced the in situ controllable growth of zinc/cobalt bimetallic-organic frameworks (Zn/Co-MOF), ultimately yielding a bimetallic MOF-functionalized electrospun nanofibrous membrane (BMF-PLA), which was characterized by a hierarchical micro/nano structure and a substantially increased specific surface area. The BMF-PLA membrane exhibited a hierarchical roughness structure, formed by bimetallic MOF nanoparticles uniformly anchored onto the fiber surfaces with robust interfacial bonding. This unique structure significantly enhanced airflow flux and particulate matter filtration efficiency. The BMF-PLA membrane achieved high filtration efficiencies of up to 99.22% for PM_2.5 and 97.65% for PM_0.3, appealing for air purification applications. This effort provides an effective and feasible surface functionalization strategy for developing high-performance PLA filter materials, offering new insights for designing the next-generation, sustainable and high-performance protective membranes.

In this study, a new class of highly transparent hole transporting materials (HTMs), namely PBN-3,6-Cz and PBN-2,7-Cz, were been designed and synthesized by copolymerizing carbazole with 3,3″-benzo[e]-cyclopenta[b]indole-substituted p-terphenyl units. This molecular design aimed to mitigate parasitic absorption in the hole transport layer of inverted perovskite solar cells (PSCs). Both polymer HTMs exhibited appropriate energy levels and high hole mobility, while achieving optical average transmittance values exceeding 94% in the 350-450 nm range, significantly higher than that of the reference PTAA (82.3%). This high transparency effectively minimized the optical losses from interfacial parasitic absorption. By tailoring the substitution sites of the carbazole units, we further regulated the charge transport properties of the polymers and the crystallization behavior of the perovskite films. As a result, the inverted PSCs based on PBN-2,7-Cz achieved a power conversion efficiency of 18.21% and a short-circuit current density of 24.33 mA·cm^-2, surpassing the performance of the reference PTAA-based devices (18.07% and 24.03 mA·cm^-2).

Stimuli-responsive surface wrinkle patterns show great application potential in the field of optical encryption and anti-counterfeiting, but their programmable generation and reversible rapid erasure remain key challenges to be overcome in this field. In this work, a bilayer film system was constructed based on poly(vinyl alcohol) (PVA) and polydimethylsiloxane (PDMS). Surface wrinkles with structural colors were achieved by utilizing the difference in elastic modulus between the two materials. This system has the ability of synergistic regulation of mechanical and humidity dual responses: uniaxial stretching triggers the appearance of wrinkles, and artificial exhalation (humidity stimulation) can trigger rapid erasure (<1 s). Three strategies were adopted to realize the programmable generation of wrinkle patterns: first, a regional mask spin-coating method was used to selectively construct the PVA top layer, and the bilayer film was subjected to uniaxial stretching followed by release to obtain the pattern; second, the bilayer system in the stretched state was treated with ultraviolet ozone (UVO) mask, and by regulating the elastic modulus of PVA in different regions, the wrinkle patterns (such as numbers "8", "3" and "7") could be controlled to appear sequentially during the stress release process; third, a microelectronic printer was used for programmable spraying of inorganic salt solution, which destroys the intramolecular and intermolecular hydrogen bonds of PVA, thereby inhibiting the formation of wrinkles in the inkjet area while wrinkles are generated in the non-inkjet area to achieve patterning. All the above wrinkle patterns are affected by humidity and can be rapidly erased by artificial exhalation (<1 s). After 1000 cycles of repeated stretching and release at 60% pre-strain, the appearance and disappearance of the patterns are not affected, showing good stability. Such wrinkle patterns with both simple uniaxial stretching response and humidity control characteristics have broad application prospects in the fields of optical encryption and anti-counterfeiting, intelligent display and so on.

Ionogels, known for their high safety and wide electrochemical windows, show great potential in energy storage. However, existing ionogels often struggle to balance high strength with dynamic properties, making it difficult to achieve an optimal combination of mechanical performance, self-healing capability, and ionic conductivity. To address this challenge, this study presents a novel ionogel electrolyte that integrates good flexibility, high mechanical strength, a wide electrochemical window, and rapid self-healing functionality. The self-healing system of the electrolyte is constructed through a dual dynamic crosslinking mechanism: on one hand, imidazole-zinc (Im-Z) metal coordination is introduced to form a dynamic high-strength crosslinked network; on the other hand, ion-dipole (Ion-D) interactions between the ionic liquid (IL) and ―CF₃ groups on the polymer chains are utilized to regulate chain segment mobility, thereby optimizing ion transport performance. Owing to this structure, the ionogel achieved a high self-healing efficiency of 94% and a tensile strength of 80 kPa. Moreover, the material exhibits a high ionic conductivity of 0.36 mS/cm, lithium-ion transference number of 0.46, and wide electrochemical window of 4.32 V, all of which contribute to the comprehensive improvements in the performance of solid-state lithium batteries. A Li/LiFePO₄ full cell assembled with this ionogel maintained a capacity retention rate as high as 80 % after 500 cycles at 0.5 C. This study elucidates the regulatory mechanism of supramolecular structural design on ion transport behavior and chain segment dynamics in ionogels, providing a theoretical basis for developing high-performance energy storage materials.

To resolve the problems of traditional lead-based substrates, such as low shielding efficiency in the energy range of 40-88 keV, biological toxicity, and the deterioration of mechanical properties caused by filler agglomeration in epoxy matrix, we put forward a "core-shell structure optimization-surface chemical bonding" strategy to fabricate gadolinium-bismuth-epoxy composite shielding coatings. Using gadolinium oxide and bismuth oxide as the cores, Bi@Si/Gd@Si core-shell nanoparticles were synthesized. Subsequently, the amino groups were introduced onto the surface of the nanoparticles through KH550 modification. Finally, these nanoparticles were compounded with epoxy resin. After ultrasonic dispersion and a heat curing process, the gadolinium-bismuth-epoxy composite shielding coatings were successfully fabricated. Both the thermal stability and mechanical properties of the composite coatings were enhanced by incorporation of fillers. The bonding strength of the composite coatings (with 50% filler loading) reached 25.80 MPa. The X-ray shielding efficiency of the coatings for ¹²⁹I source was 93.8%. The theoretical thickness required to half shielding of the intensity of γ-rays from ¹³⁷Cs source was 3.63 cm. This coating combined high bonding strength and excellent shielding efficiency could be applied to the equipment via spraying or other techniques, thus presenting broad application prospects in fields such as nuclear power plants and space station protection.

Regulating the viscoelasticity of thermoplastic elastomers (TPE) to achieve speed-induced extensibility (SIE) behavior, where the modulus, strength, and elongation at break increase simultaneously with increasing tensile rate, is an intriguing scientific issue. In this study, dihydroxyl-terminated poly(dimethylsiloxane) (PDMS) and poly(tetrahydrofuran) (PTMEG), which are thermodynamically incompatible, were selected as soft segments. By adjusting the hard segment content, a series of thermoplastic polyurethane (TPU) elastomers with a dual soft-phase structure were constructed. In situ small-angle X-ray scattering (in situ SAXS) was employed to track the structural evolution of these elastomers during deformation. It was proposed that the interface diffusion and mixing of the dual soft-phase significantly prolong the relaxation time of chains, thereby promoting large-scale chain slippage, leading to distinct SIE behavior. The confirmation of this process provides a new perspective for understanding the microstructural evolution of TPE during long-range deformation and will offer guidance for the design of novel high-performance elastomers.

Using the semi-prepolymerization method as the core process, a series of kaolin/polyurethane elastomer composites were prepared. The effects of kaolin content and calcination temperature on the mechanical properties, damping, and sound insulation were systematically investigated. The results indicate that uncalcined kaolin exhibited optimal dispersion at a loading of 0.5 wt%, enhancing the mechanical performance of the composite relative to that of the neat matrix. When the filler content increased to 1 wt%, the damping properties improved markedly. The synergistic effect of the acoustic impedance mismatch and enhanced damping led to an overall improvement in sound insulation across the 50-6400 Hz frequency range, with samples with higher filler content exhibiting more pronounced performance. Calcination above 600 ℃ converted kaolin into metakaolin and improved its compatibility with the polyurethane matrix. When treated at 800 ℃, the resulting metakaolin composite attained a hydrogen-bonding index of 2.33, maintained a tensile strength of 11.9 MPa, and reached a tanδ value of 0.84, delivering the best overall synergy in mechanical and damping properties. A comprehensive analysis indicated that the synergistic control of kaolin content and calcination temperature significantly enhanced the strength, toughness, damping, and sound insulation properties of polyurethane elastomers. This provides new insights and technical pathways for designing and preparing lightweight, high-damping, and high-sound-insulation structural vibration-damping materials.

The driving force for high-pressure crystallization of polymers is undercooling. According to the pressure-melting point phase diagram of nylon 6 (PA6), sufficient pressure (target pressure) can generate adequate undercooling to induce crystallization during pressurization. In this work, a self-designed variable-speed diamond anvil cell (s-dDAC) was employed to subject PA6 to rapid pressurization treatment at a pressurization rate of 1 GPa/s. The effect of target pressure on the crystallization behavior of PA6 was investigated in situ using multiple structural characterization techniques. The results demonstrated that target pressure significantly influenced both the crystal polymorphism and crystallization process of PA6. When the target pressure was ≤2.5 GPa, the melt could not completely solidify during pressurization, exhibiting crystallization lag, and the resulting samples consist of a mixed phase dominated by α-phase with minor β-phase content. When the target pressure was ≥3.0 GPa, the crystallization lag disappears, and the samples comprise a mixed phase dominated by β-phase with minor α-phase content. Regardless of target pressure, the critical pressure at which PA6 melt initiated solidification remains nearly constant at approximately 340 MPa. When the target pressure was ≥3.0 GPa, PA6 melt can continuously solidify within a "pressure window" ranging from 340 MPa to 2.7 GPa. During depressurization, the volume of β-phase crystals continuously expanded, accompanied by partial crystal destruction. This work represents the first successful preparation of β-phase-containing PA6 products via rapid pressurization method, with in situ observation of both the pressurization-induced formation process and depressurization-induced destruction process, demonstrating that modulating pressurization conditions can not only control the crystallization kinetics of PA6 but also enable the fabrication of products with distinctive structures.

To address the challenge of spinning poly(hexamethylene terephthalamide-co-hexamethylene adipamide) (PA6T-66) due to its high melting point and poor melt fluidity, this work first adopted melt blending with polycaprolactam (PA6). Triphenyl phosphite (TPP) was introduced as a compatibilizer to enhance compatibility, successfully producing compatibilized PA6T-66/PA6 composite fibers. The structure and properties of the fibers were systematically analyzed. The results indicated that with an increasing PA6 content, the melt fluidity of the blend significantly improved while its melting point markedly decreased. When the mass fraction of PA6T-66 was 40%, the prepared composite fiber achieved a breaking strength of 4.64 cN/dtex and retained 93% of its strength after thermal aging. Furthermore, the addition of the compatibilizer caused the molecular weight of the blend system to first increase and then decrease. After adding 0.5% compatibilizer, the melting point of the blend decreased from 274.9 ℃ to 272.6 ℃, and the molecular weight increased from 19,530 g/mol to 24,100 g/mol. Fibers prepared based on this optimized system exhibited a further enhanced breaking strength of 6.23 cN/dtex, while the strength retention rate after thermal aging remained at 93%.

To enhance the interfacial compatibility and dispersion of lignin within the natural rubber (NR) matrix, thereby enhancing the mechanical properties of the rubber composite, dodecylated lignin (DL) was synthesized through alkylation modification, and a hybrid filler system was constructed by incorporating it with carbon black (CB). The influence of the DL/CB ratio on the properties of NR composites was systematically investigated. The results indicated that the incorporation of DL reduced the optimum curing time and Mooney viscosity of the composites, effectively improved the dispersion of the fillers in the rubber matrix, and significantly enhanced the mechanical properties, thermo-oxidative aging resistance, and flex resistance of the composites. Among the tested formulations, the NR-10DL/40CB composite exhibited the best performance. While maintaining thermal stability, tensile strength, and wet skid resistance comparable to those of the NR-50CB benchmark, the NR-10DL/40CB composite achieved a remarkable 21.1% increase in elongation at break. Furthermore, the thermal oxidative aging coefficient and the number of flex cracking cycles were improved by 31.1% and 41.4%, respectively, while the rolling resistance and cut resistance were optimized. These findings demonstrate the promising potential of the composite for application in rubber products such as tires and conveyor belts.

External stimuli can induce composition conversion in block copolymers, which can then lead to morphological transitions of the block copolymer aggregates from one ordered state to another, which has become a new strategy for regulating the morphological structure of block copolymers. Based on this, taking the classical ABA triblock copolymer ordered aggregates (such as cylinders and vesicles) as the initial state, the Monte Carlo simulation method was used to investigate the microstructural changes in the hydrophobic parts of the cylinder and vesicle when part of the B blocks in the system were converted into C blocks (i.e., the ABA triblock copolymer in the system was transformed into the ABA/ACA triblock copolymer mixture). The simulation results indicated that by regulating the incompatibility between the B block and the newly generated C block, as well as the evolution time of the system, ordered aggregates with a single hydrophobic component could evolve into ordered aggregates with a variety of novel controllable multi-compartment structures that are rarely observed in linear terpolymer systems, such as segmented worm, Hamburg-type and Janus-type rods, pupa-like vesicles, softball-shaped vesicles, Janus-type and dumbbell-shaped vesicles. It is worth noting that some of the aforementioned structures, such as segmented worms and pupa-like vesicles, are difficult to obtain using traditional self-assembly methods (i.e., the system evolves from a disordered uniform solution state) under the same parameter conditions.