High-strength water-resistant reed fiber/ silicate hollow composites fabrication via responsive interface design

In response to the "dual carbon" strategy, the combination of reed waste and Portland cement to synthesize lightweight composites is crucial for promoting building energy conservation, carbon sequestration, and emission reduction. However, traditional biomass-based lightweight composites exhibit poor interfacial compatibility and numerous micropores, leading to weak water resistance and mechanical strength. These issues significantly limit the potential applications of these composites in various fields. Here, we synthesized epoxidized cardanol acetate (ECA) and utilized its response characteristics in alkaline slurry environment to decompose and recombine molecular chains, thereby improved the interfacial compatibility of hollow composites and achieved dense integration of their wall layers. The research strategy mainly involved the hydrolysis of −COOCH 3 in ECA, which released carboxyl and hydroxyl groups. The hydroxyl groups formed bonds with reed fibers, while the carboxyl groups chelated with silicate crystals. This resulted in a chemical "molecular bridge," which bonded the reed fibers to the silicate cement. The hydrolyzed long-chain ECA molecules formed a polymer network within the composites, which improved the overall stability of the hollow wall structure. Compared with ordinary hollow composites, the compressive strength of hollow composites prepared by this method increased by 73 %, and the bending strength increased by 50 %, with higher mechanical strength. The softening coefficient of composites was 0.93, with excellent water resistance and good thermal insulation performance. These reed fiber/Portland cement-based hollow composites have significant potential applications in building energy efficiency, non-load-bearing infill walls, and prefabricated buildings. • Independently synthesized epoxy polymers that can respond and react in alkaline environments. • Utilized the decomposable and recombinable properties of ECA molecular chains to construct a 'molecular bridge' at the interface. • Realized dense integration of hollow wall layers in composites.