Chinese Journal of Polymer Science最新文献

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.

Polyaniline (PANi) hydrogels have a wide range of applications in artificial skin, flexible robotics, and movement monitoring. Nevertheless, limited by the modulus mismatch between rigid PANi and the soft hydrogel matrix, the high strength and toughness of the PANi hydrogel are mutually exclusive. Although the introduction of sacrificial bonds into the hydrogel network can alleviate this contradiction to a certain extent, it always causes pronounced energy hysteresis during hydrogel deformation. Inspired by the energy storage and release of macroscopic springs, in this work, we propose a molecular entanglement approach for the fabrication of PANi hydrogels featuring high toughness and low hysteresis, where flexible poly(ethylene glycol) (PEG) is entangled with chemically cross-linked poly(acrylic acid) (PAA) as a hydrogel matrix, and rigid PANi as a conductive filler. The resultant PAA/PEG/PANi hydrogel exhibited high mechanical properties (fracture strength of 0.75 MPa and toughness of 4.81 MJ·m⁻³) and a low energy dissipation ratio (28.2% when stretching to 300%). Moreover, the PAA/PEG/PANi hydrogel possesses a good electrical response to external forces and can be employed as a strain sensor to monitor human joint movements by producing specific electrical signals. This work provides a straightforward strategy for preparing tough conductive PANi hydrogels with low hysteresis, showing potential for the development of healthcare devices.

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.

Photonic fibrous soft actuators that can modulate light and produce responsive deformation would have broad technological implications in areas, ranging from smart textiles and intelligent artificial muscles to medical devices. However, creating such multifunctional soft actuators has proved tremendously challenging. Here, we report novel cholesteric liquid crystal elastomer (CLCE) based photonic fibrous soft actuators (PFSAs). CLCE can serve as chiral photonic soft active material and allow for multiresponse in shapes and colors. We leveraged a tubular-mold-based processing technology to prepare fibrous CLCE actuators, and the prepared actuators exhibit the capabilities to dynamically switch structural colors and geometrical shapes by mechanical, temperature, or light stimuli. CLCE-based PFSAs demonstrate diverse functionalities, including visual weight feedback, optically driven object manipulation, and light driven locomotion. It is anticipated that our PFSAs would offer many new possibilities for developing advanced soft actuators.

Soft robots have shown great advantages with simple structure, high degree of freedom, continuous deformation, and benign human-machine interaction. In the past decades, a variety of soft robots, including crawling, jumping, swimming, and climbing robots, have been developed inspired by living creatures. However, most of the reported bionic soft robots have only a single mode of motion, which limits their practical application. Herein, we report a fully 3D printed crawling and flipping soft robot using liquid metal incorporated liquid crystal elastomer (LM-LCE) composite as the actuator. With the application of voltage, liquid metal works as the conductive Joule heating material to induce the contraction of the LCE layer. The bending angle of the LM-LCE composite actuator highly depends on the applied voltage. We further demonstrate that the soft robot can exhibit distinct moving behaviors, such as crawling or flipping, by applying different voltages. The fully 3D printed LM-LCE composite structure provides a strategy for the fast construction of soft robots with diverse motion modes.

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.