Kai Jin

Durable bonding across dissimilar material interfaces is essential for pipeline connections exposed to low temperatures, saline and corrosive environments, such as subsea and hydrogen transportation pipes. In this study, two cardanol-derived mussel-inspired curing agents with distinct diamine architectures were synthesised to regulate the low-temperature performance of epoxy interfaces between multiple materials commonly seen in pipeline systems, in terms of steel, Aluminium and PMMA. In the epoxy interfaces, flexible M1-EP contains a flexible aliphatic decamethylene spacer, whereas rigid M2-EP incorporates a relatively rigid aromatic m-xylylene unit. Comparable amine values allowed the influence of molecular architecture to be distinguished from differences in curing capacity. The DSC and DMA showed that flexible M1-EP possessed a lower glass-transition temperature of 72.50 °C compared with 81.23 °C for rigid M2-EP, indicating greater network mobility and stress-accommodation capability. The FTIR, XPS, SEM and EDS analyses revealed seawater-induced changes in N- and O-containing groups together with ion-enriched surface regions, supporting coordination and ion-dipole interactions between seawater-derived ions and the epoxy networks. Accordingly, both systems exhibited enhanced tensile and shear strength after curing in artificial seawater. At reduced temperatures, flexible M1-EP showed markedly better mechanical retention. Its tensile strength decreased by 21% from 20 to -40 °C, compared with 34% for rigid M2-EP, while its shear strength remained 14.56 MPa at -40 °C. M1-EP also exhibited stronger adhesion across aluminium, PTFE and PMMA substrates. After 50 freeze-thaw cycles, M1-EP retained a shear strength of 13.36 MPa compared with 10.53 MPa for M2-EP. The EIS further demonstrated slower interfacial degradation of M1-EP during prolonged cold seawater ageing and repeated freeze-thaw cycling. These results demonstrate that flexible diamine architecture effectively balances seawater-induced interfacial reinforcement with low-temperature stress accommodation, providing a molecular design strategy for durable epoxy bonding of heterogeneous interface in extreme environment for subsea couplers and hydrogen pipeline connections.

Chemical grafting for constructing surface topography is a useful strategy for enhancing the performance of carbon fiber composites. Inspired by the anchoring structure of kelp holdfast, we propose a magnetically guided double-layer grafting strategy to construct a bionic array on carbon fibers. This approach uses a covalent organic framework (COF)-based silane coupling and ferroferric oxide (Fe3O4) to achieve a two-step covalent functionalization, resulting in a biomimetic carbon nanotubes (CNTs) based nanostructure (denoted as CF/CNT/CNT@Fe3O4). Comprehensive characterization using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated the formation of this hierarchical interfacial layer. The modified fibers exhibit improved wettability with an epoxy (EP) matrix, as evidenced by contact angle measurements. Consequently, the resulting carbon fiber-reinforced polymer (CFRP) composites exhibited improvedl interfacial and mechanical properties, with interfacial shear strength, interlaminar shear strength, and flexural strength increasing by 130%, 93%, and 73%, respectively, compared to composites with unmodified fibers. This work presents a surface modification strategy integrating magnetic-field-induced assembly, two-step grafting, and biomimetic design, offering a feasible approach for the surface modification of high-performance reinforcing fibers.

The rapid development of deep‐sea exploration has increased the demand for lightweight materials with high load‐bearing capacity and energy absorption under compressive loading. In this study, the mechanical response of conventional carbon fiber‐reinforced polymer (CFRP)–Nomex honeycomb sandwich structures was enhanced by filling the honeycomb core with hollow glass microspheres (HGM). Three configurations were investigated: an HGM syntactic foam with CFRP skins (HC), a Nomex honeycomb core with CFRP skins (NC), and an HGM‐filled Nomex honeycomb core with CFRP skins (NHC). Flatwise compression experiments and finite element analysis were conducted to quantify compressive strength and energy absorption, and artificial seawater immersion tests (6‐day exposure) were performed to evaluate the retention of stiffness and peak compressive load. The results show that NHC exhibits the highest compressive strength, achieving a 308% increase in compressive strength compared with NC. NHC also demonstrates superior energy absorption (109 J) relative to HC (44.7 J) and NC (5.52 J), corresponding to an approximately 19‐fold increase in specific energy absorption. Following the artificial seawater immersion, NHC retains stiffness and compressive performance more effectively than NC. These findings indicate that HGM‐filled Nomex honeycomb CFRP sandwich structures represent a promising approach for lightweight, energy‐absorbing core design with potential applicability in deep‐sea engineering.

Delivering nanocomposites that combine high strength, toughness, and multifunctionality remains a major challenge, as conventional trial‐and‐error and design‐of‐experiments approaches cannot efficiently resolve trade‐offs in high‐dimensional design spaces. We introduce a machine‐learning–assisted bio‐interfacial design framework integrating Gaussian‐process surrogates, Pareto set learning, and active learning to explore composition–processing spaces under calibrated uncertainty. The workflow converges after nearly 60 experiments, reducing experimental count, project duration, and cost by 74%–85% relative to conventional methods, thereby accelerating design cycles and expanding Pareto coverage. Guided by this approach, we realize mycelium–graphene composites with strength >58 MPa, toughness >6 MJ/m ³ , and levitation >0.14 mm, showing that strength can be maintained while toughness is significantly enhanced and multifunctionality unlocked. Mechanistic analyses reveal nanosheet‐pinned, hierarchically entangled interfaces where hydrogen‐bonded junctions enable reversible nanosheet sliding, crack deflection, and adaptive stress transfer. These architectures impart levitation control, laser‐driven actuation, and self‐healing. Extension to MXene systems yields composites with enhanced resilience and electromagnetic interference shielding above 40 dB, confirming the generality of the strategy. Together, these advances define a scalable and sustainable paradigm for the accelerated discovery of robust, multifunctional nanocomposites.

1. The mechanical integrity and functional performance of polymer nanocomposites are intrinsically governed by the quality of the interfacial adhesion between the continuous organic matrix and the ...

Developing polymer composites that simultaneously achieve high strength, toughness, and impact resistance remains a fundamental challenge due to inherent trade-offs and brittle interfacial failure. Here, we propose a universal toughening strategy that integrates a bone-inspired trabecular interlock architecture with a thermodynamically driven, stress-adaptive interface to enable efficient energy dissipation under mechanical loading. To address multi-objective optimization in composites design, we further develop a data-driven framework combining Pareto Set Learning and Active Learning, which systematically explores the composition–performance landscape to identify balanced, high-performance formulations. The optimized composites exhibit synergistic mechanical properties: strength up to 250 MPa, fracture toughness exceeding 14 MPa·m^1/2, and impact resistance of nearly 4.8 J, surpassing most bioinspired and engineered polymer counterparts. The strategy is scalable, chemically versatile, and broadly applicable, offering a programmable route to next-generation lightweight composites for aerospace, transportation, and protection.

With rising interest in various offshore equipment, bridges, and marine engineering, it is necessary to develop an epoxy resin adhesive that can cure quickly under seawater and has high bonding performance. In this paper, through mimicking mussel adhesive proteins, a biomimetic epoxy resin is designed and prepared for seawater adhesion. A mussel dopamine‐like structure with cashew phenol and catechol as the main structure is prepared by the Mannich reaction, and the amino acids in mussel adhesive protein are simulated by the addition of decamethylene diamine. The results show that the adhesive has higher seawater bonding strength (17.65 MPa) and tensile strength (30.31 MPa) under the condition of seawater solidification. The cross‐section morphology of the adhesive is still a typical ductile fracture due to the adhesive retaining the toughened properties of the cashew phenol structure, while the catechol structure provides a stronger bonding ability. The apparent activation energy is 45.22 kJ mol ⁻¹ indicating in a high curing activity. The ions in seawater can participate in the bonding process of the adhesive, and non‐covalent bonds can be formed in the process. The construction strategy that mimics the mussel adhesive protein structure can also be used to design other seawater adhesives.

Lightweight structural composite materials are widely used in automobiles, aerospace, and other fields. However, achieving the integration of structural and functional properties, such as the ability to monitor external forces, remains a significant challenge. Nacre and turtle shells in nature are strong and tough due to their unique ordered structure of alternating soft and hard phases. Inspired by this, an interface anchoring strategy is proposed which leverages hyphae (filamentous structure forming the vegetative part of fungi) to fix the hard‐phase graphene nanosheets (GNs) and the soft‐phase intertwined polymer matrix to form theree‐dimentional (3D) layered bulk composites (LBCs). The growth pattern of fungi is utilized to place GNs and assemble polyethylene glycol‐polyvinyl alcohol (PEG‐PVA) to fabricate the LBCs, which is different from most existing preparation methods of bulk biomimetic composites. The LBCs exhibit self‐regenerative capabilities and are amenable to scalable manufacturing. These composites demonstrate impressive mechanical properties, including a specific strength of 92.8 MPa g cm⁻³, fracture toughness of 6.5 MPa m^−1/2, and impact resistance of ∼3.1 kJ m⁻², outperforming both natural nacre and other biomimetic layered composites. Furthermore, the LBCs display effective protective warning functions under external force stimulations, making them a promising material for anti‐collision applications in industries such as sports and aerospace.