Chinese Journal of Polymer Science最新文献

Thermosets are indispensable to our daily life, but their crosslinked structures make them unable to be processed by the melt processing like thermoplastics, which greatly limits their shape designs and applications. Herein, we address this challenge via an in situ self-growing strategy, i.e. utilizing the dynamic imidazole-urea moiety to suck up and integrate epoxy into the materials and making the thermoplastics grow in situ into thermosets. With this strategy, thermosets can be readily processed via hot-melt extrusion molding, including melt spinning and fused deposition modeling 3D printing. More importantly, this strategy simultaneously integrates the flexibility of polyurethane and the robustness of epoxy resin into the resulting thermosets, yielding a mechanical-reinforcing effect to make the material not only strong but also tough (toughness: 99.3 MJ·m⁻³, tensile strength: 38.8 MPa). Moreover, the crosslinking density and modulus of the as-prepared thermosets (from 34.1 MPa to 613.7 MPa) can be readily tuned on demand by changing the growth index. Furthermore, these thermosets exhibited excellent thermal stability and chemical resistance.

The strategic dispersion of carbon nanotubes (CNTs) within triblock copolymer matrix is key to fabricating nanocomposites with the desired electrical properties. This study investigated the self-assembly and electrical behavior of a polystyrene-polybutadiene-polystyrene (SBS) matrix with CNTs of different aspect ratios using hybrid particle-field molecular dynamics simulations. Structural factor analysis of the nanocomposites indicated that CNTs with higher aspect ratios promoted the transition of the SBS matrix from a bicontinuous to a lamellar phase. The resistor network algorithm method showed that the electrical conductivity of SBS and CNTs nanocomposites was influenced by the interplay between the CNTs aspect ratios, concentrations, and domain sizes of the triblock copolymer SBS. Our research sheds light on the relationship between CNTs dispersion and the electrical behavior of SBS/CNTs nanocomposites, guiding the engineering of materials to achieve desired electrical properties through the modulation of CNTs aspect ratios and tailored sizing of triblock copolymer domains.

Cholesteric liquid crystals (CLCs) exhibit unique helical superstructures that selectively reflect circularly polarized light, enabling them to dynamically respond to environmental changes with tunable structural colors. This dynamic color-changing capability is crucial for applications that require adaptable optical properties, positioning CLCs as key materials in advanced photonic technologies. This review focuses on the mechanisms of dynamic color tuning in CLCs across various forms, including small molecules, cholesteric liquid crystal elastomers (CLCEs), and cholesteric liquid crystal networks (CLCNs), and emphasizes the distinct responsive coloration each structure provides. Key developments in photochromic mechanisms based on azobenzene, dithienylethene, and molecular motor switches, are discussed for their roles in enhancing the stability and tuning range of CLCs. We examine the color-changing behaviors of CLCEs under mechanical stimuli and CLCNs under swelling, highlighting the advantages of each form. Following this, applications of dynamic color-tuning CLCs in information encryption, adaptive camouflage, and smart sensing technologies are explored. The review concludes with an outlook on current challenges and future directions in CLC research, particularly in biomimetic systems and dynamic photonic devices, aiming to broaden their functional applications and impact.

Traditional packaging plastics derived from fossil fuels for perishable foods have caused severe environmental pollution and resource depletion. To promote sustainable development and reduce wastage of perishable products, there is a significant challenge in developing bio-based packaging plastics that offer excellent preservation, satisfactory mechanical performance, and inherent degradability. In this study, poly(urethane-urea) (PUU) plastics are fabricated using a one-pot polyaddition reaction involving castor oil (CO), tannic acid (TA), lysine-derived ethyl 2,6-diisocyanatohexanoate (LDI), and H₂O. The resulting PUU plastics demonstrate a high breaking strength of about 32.7 MPa and a strain at break of ca. 102%. Due to the reversibility of hydrogen bonds, PUU plastics can be easily shaped into various forms. They are non-cytotoxic and suitable for food packaging. With a high TA content of ca. 38.2 wt%, PUU plastics exhibit excellent antioxidant capacity. Consequently, PUU plastics show outstanding freshness preservation performance, extending the shelf life of cherry tomatoes and winter jujubes for at least 8 days at room temperature. Importantly, PUU plastics can autonomously degrade into non-toxic substances within ca. 298 days when buried in soil.

Low dielectric constant (low-k) materials are critical for advanced packaging in high-density microelectronic devices and high-frequency communication technologies. Ladder polysiloxanes, which are characterized by their unique double-chain structure and intrinsic microporosity, offer remarkable advantages in terms of thermal stability, oxidation resistance, and dielectric performance. However, structural defects in ladder polysiloxanes, such as cage-like and irregular oligomers, and their effects on dielectric properties remain underexplored. In this study, a series of ladder-like polysiloxanes (X-TMS) with diverse side groups weresynthesized via a one-step base-catalyzed method. The influence of the benzocyclobutene (BCB) side groups on the formation of regular ladder structures was systematically investigated. Notably, BCB incorporation disrupted the structural regularity, favoring the formation of cage-like and irregular topologies, which were extensively characterized using ²⁹silicon nuclear magnetic resonance spectroscopy (²⁹Si-NMR), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and X-ray diffraction (XRD). These structural defects were beneficial for improving the hydrophobicity and thermal stability. Copolymerization of X-TMS with commercial DVS-BCB resins further enhanced the mechanical properties, with the elastic modulus increasing from 3.6 GPa to 4.4 GPa and water absorption reduced from 0.33 wt% to 0.06 wt%. This study establishes a clear correlation between topological structures and material properties. These findings not only advance the understanding of the structure-property relationships in ladder polysiloxanes but also provide a novel approach for designing high-performance interlayer dielectric materials for next-generation microelectronics.

The burgeoning ethylene production in the Asia-Pacific region has led to a substantial oversupply of butadiene as a byproduct, and it is highly important to develop new butadiene-based materials. Butadiene-maleic anhydride copolymer, characterized by its amphiphilic nature, shows potential applications in adhesives, emulsifiers, etc. However, the Diels-Alder (DA) reaction of butadiene and maleic anhydride competes with the polymerization, limiting the copolymer yield. In this study, the kinetics of the DA reaction and copolymerization between butadiene and maleic anhydride were examined, and the influence of various reaction conditions on the copolymer yield was investigated. We found that the DA reaction in the induction period of the radical polymerization was the critical factor in limiting copolymer yield. Therefore, we proposed the two-step method to suppress the DA reaction and achieve high-yield production (∼85%) of cross-linked microspheres with controllable particle size (175–800 nm) by self-stabilized precipitation polymerization. This work enables an efficient synthesis of conjugated diolefin-maleic anhydride cross-linked microspheres, offering a novel approach to address the issue of butadiene overcapacity.

Ring polymers are ubiquitous in various fields including biomaterials, drug release and gene therapy. All of these applications involve the dynamics and diffusion process of ring polymers in a confined environment. By using dynamic light scattering (DLS), we discovered a dynamical transition for charged ring polymers with increasing ring concentration in the gel matrix from a diffusive state to a non-diffusive topological frustrated state with a more compact conformation. When the ring polymer size is smaller than the mesh size of the gel matrix, the rings are diffusive at low concentration of 5 g/L. The ring diffusion coefficient in the gel matrix is an order of magnitude smaller than that of rings in solution, obeying the Ogston’s model. At high ring concentration of 40 g/L, the collective dynamical behavior of the charged rings exhibits a topologically frustrated non-diffusive state, which may originate from the inter-ring threading with the external confinement from the gel matrix. Based on our previous theoretical work, we also conjectured that in such a non-diffusive state, the ring polymers might adopt a more compact conformation with the overall size exponent v=1/3.

In the event of the ever-increasing growth of the beauty industry and the burgeoning market for facial masks, high-performance and high-safety mask products have emerged. Among these, light-cured collagen peptide-based hydrogels, which are non-toxic, photocurable natural materials, exhibit significant potential for use in facial masks. We developed a novel collagen peptide-lithium chloride hydrogel-based facial mask. Light-cured collagen peptide hydrogel is a non-toxic, light-activated natural material that holds considerable promise for application in facial masks. Nonetheless, there is a significant lack of effective methodologies for real-time assessment of skin quality currently available in the market. To address this deficiency, we have developed an innovative collagen peptide-lithium chloride hydrogel mask, which is characterized by exceptional transparency (98% within the visible spectrum of 400–800 nm), commendable tensile properties (tensile strength of 428.6±2.1 kPa, with a tensile strength increase of 123.9%), substantial water retention capacity (61%), and favorable antimicrobial efficacy (89%). The incorporation of lithium chloride enhances ionic conduction at the interface between the human body and hydrogel, thereby enabling quantitative evaluation of skin quality through impedance analysis. Our collagen peptide-lithium chloride hydrogel facial mask demonstrated effectiveness in distinguishing various skin types, including D⁺ (severely dry), D (mildly to moderately dry), N (moderate), O (mildly to moderately oily), and O⁺ (severely oily). This study presents significant opportunities for the advancement of hydrogel masks and provides a new application platform for polymer hydrogels.

Polymerization-induced self-assembly (PISA) has become one of the most versatile approaches for scalable preparation of linear block copolymer nanoparticles with various morphologies. However, the controlled introduction of branching into the core-forming block and the effect on the morphologies of block copolymer nanoparticles under PISA conditions have rarely been explored. Herein, a series of multifunctional macromolecular chain transfer agents (macro-CTAs) were first synthesized by a two-step green light-activated photoiniferter polymerization using two types of chain transfer monomers (CTMs). These macro-CTAs were then used to mediate reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of styrene (St) to prepare block copolymers with different core-forming block structures and the assemblies. The effect of the core-forming block structure on the morphology of block copolymer nanoparticles was investigated in detail. Transmission electron microscopy (TEM) analysis indicated that the brush-like core-forming block structure facilitated the formation of higher-order morphologies, while the branched core-forming block structure favored the formation of lower-order morphologies. Moreover, it was found that using macro-CTAs with a shorter length also promoted the formation of higher-order morphologies. Finally, structures of block copolymers and the assemblies were further controlled by changing the structure of macro-CTA or using a binary mixture of two different macro-CTAs. We expect that this work not only sheds light on the synthesis of block copolymer nanoparticles but also provide important mechanistic insights into PISA of nonlinear block copolymers.

Sodium alginate (SA) is generally considered highly hydrophilic due to two hydroxyl groups and a carboxylate group on each pyranose ring. However, SA will form a gel after dissolving in water for a certain period. The two properties of SA, hydrophilicity and gelation, seem to be paradoxical. In this study, to explore the mechanism behind these paradoxical properties, the single-chain behaviors of SA in various liquid environments have been investigated by using single-molecule force spectroscopy (SMFS). In nonpolar solvents such as nonane, SA exhibits its single-chain inherent elasticity consistent with the theoretical elasticity derived from quantum mechanical (QM) calculations. Notably, the experimental curve of SA obtained in water shows a long plateau in the low force region. Further research reveals that this phenomenon is driven by the hydrophobic effect. Additionally, SA shows greater rigidity than its inherent elasticity in the middle and high force regions due to electrostatic repulsion between carboxylate groups on adjacent sugar rings. Comparative single-molecule studies suggest that SA exhibits considerable hydrophobicity, offering new insights into the gelation process in water.