Molecular-level topological deep cross-fusion strategy towards organic–inorganic lightweight composites

[Display omitted] •A molecular topological structure of composites was constructed.•A deep cross fusion strategy for heterogeneous interfaces was developed.•The specific strength of composites was improved by 350%. The demand of thermal energy conservation and regulation using inorganic composites in green low-carbon modern society is urgent. However, the organic–inorganic heterogeneous interfacial compatibility in traditional inorganic composites mainly depends on the loose crystal layers via hydrogen bonding, which is prone to faults and the hole wall damaged under strong forces. Here, a molecular topological structure was constructed in the composites system. Our process includes generating dendritic molecular chains on bamboo fiber, activating crystals to increase active sites, and inducing the confined growth of crystals on bamboo fiber through the action of hydrogen bonding and electrostatic adsorption. A chitosan-acrylic acid graft copolymer (CS-g-PAA) was introduced, which responded to weak alkali environment, achieved multi-mode bonding effects such as dynamic hydrogen bond, ionic complex bond, enhanced covalent bond, metal coordination bond and polymer network. Therefore, achieving deep cross fusion of heterogeneous interfaces through this method endows topologically composites (TCS) with many unique properties such as lightweight ultrastrong, thermal insulation, shock absorption, and fire resistance. The TCS was 8 times stronger than traditional insulation materials, and the thermal conductivity (0.07–0.085 W·m−1·k−1) was much lower than that of other inorganic insulation materials. This multifunctional TCS shows potential applications for building energy conservation, aerospace insulation, and aircraft arresting systems.