Ping Han

Developing efficient surface modification strategies to enhance interfacial adhesion has become a crucial research direction for fully exploiting the mechanical and functional capabilities of carbon fiber-reinforced polymer (CFRP) composites. In this study, based on the concept of organic-inorganic multi-scale heterogeneous structure design, we demonstrated the process of assembling organic tannic acid/(3-aminopropyl) triethoxysilane (TA/A) three-dimensional(3D) nanospheres and inorganic MXene (MX) two-dimensional(2D) nanosheets onto the surface of carbon fiber (CF) to prepare high-performance MX-TA/A-modified CF/epoxy (CF/EP) composites. The spherical TA/A nanostructures not only increase the surface roughness of CFs, generating mechanical interlocking with the EP matrix, but also provide a hierarchical interface that enhances stress distribution under external loading. Moreover, the incorporation of MX nanosheets introduces a high-aspect-ratio nanostructure with abundant surface terminations, providing additional active sites for interfacial interactions and serving as a mechanical reinforcement that resists interfacial debonding. The TA/A–MX assembly strategy provides a versatile and sustainable route for designing multifunctional interfacial layers on CFs. It effectively integrates the benefits of polyphenol adhesion chemistry, silane coupling, and 2D nanomaterial reinforcement. This approach not only enhances the interfacial bonding strength and toughness of CFRP composites but also offers a generalizable platform for fabricating high-performance fiber-reinforced materials for aerospace, automotive, and structural applications.

Flexible strain sensors hold considerable potential for human-machine interaction and health monitoring, yet conventional single-network systems often suffer from brittleness, limited durability, and insufficient multifunctionality. Herein, a multifunctional polyacrylamide (PAAm)/polyvinyl alcohol (PVA) composite hydrogel incorporating tannic acid-modified lignin (TA@AL) is developed via a simple one-pot polymerization followed by Fe³⁺ post-impregnation. A hierarchical triple-network structure is constructed, consisting of (i) a covalent PAAm backbone, (ii) a physically interpenetrated PVA network stabilized by hydrogen bonding, and (iii) a dynamic metal–phenol coordination network between TA@AL and Fe³⁺. Owing to this synergistic architecture, the hydrogel exhibits a high tensile strength of 115 kPa, a fracture strain of ~900%, and a toughness of 0.45 MJ m⁻³, together with robust adhesion and high ionic conductivity (0.75 S m⁻¹). Density functional theory (DFT-D3) calculations further reveal the coordination energetics between Fe³⁺ and different polymer ligands, demonstrating that multidentate coordination in the PAAm/PVA/TA system provides strong yet dynamic binding, which underpins efficient energy dissipation and mechanical robustness. Benefiting from the coupled mechanical and electrical properties, the hydrogel functions as a high-performance strain sensor with high sensitivity, fast response, and excellent cycling stability, enabling accurate detection of both large-amplitude joint motions and subtle physiological signals such as swallowing and handwriting. This work not only offers an effective strategy for lignin valorization but also provides a molecular-to-macroscopic design framework for high-strength, conductive, and multifunctional hydrogels for wearable and biomedical applications.

The combination of peptide nanosheets and magnetic Fe ₃ O ₄ nanozymes promotes colorimetric detection and selective adsorption of Hg ²⁺ .

An optimized “rigid-flexible” structure with multistage gradient modulus was constructed on carbon fiber (CF) surface via chemical grafting using “flexible” polyethyleneimine (PEI) and “rigid” polydopamine (PDA) between “rigid” CF and “flexible” epoxy (EP) to elaborate a double alternant “rigid-flexible” structure for simultaneously strengthening and toughening CF/EP composites. PDA and PEI polymers can greatly enhance the roughness and wettability of CF surfaces, further strengthening the mechanical interlocking and chemical interactions between CFs and epoxy. Besides, the “rigid-flexible” structure endows the interface with a gradient transition modulus, which could uniformly transfer internal stress and effectively avoid the stress concentration. Moreover, the double alternant “rigid-flexible” could buffer the external loading, induce more micro cracks and propagation paths and, thereby, consume more energy during the destruction of the composite. The interfacial shear strength, interlaminar shear strength, impact strength increased by 80.2%, 23.5% and 167.2%, and the fracture toughness improved by 227.2%, compared with those of the unmodified CF composite, respectively. This creative strategy and design afford a promising guidance for the preparation and production of advanced CF/EP structural materials with high strength and toughness.