Hydrophilic bamboo powder-reinforced cellulose composite foams with tailored hydrogen bonding network for structural cushioning applications

The structural collapse of all-biomass foams during hot-air drying severely limits their formability and mechanical integrity, hindering practical applications. Herein, we present a multiscale reinforcement strategy using cationically modified bamboo powder (CBP) as a structural and functional additive to cellulose-based foams. The CBP exhibits enhanced hydrophilicity and surface charge, enabling strong hydrogen bonding and dipole–ion interactions with cellulose fibers. These interactions facilitate the formation of a robust internal network, allowing air drying without significant shrinkage and markedly enhancing compressive strength. Density functional theory (DFT) calculations confirm that hydrogen bonding is the dominant non-covalent force stabilizing the CBP-cellulose matrix. Additionally, covalent crosslinking between citric acid and cellulose via esterification further reinforces the three-dimensional architecture of the foam. The optimized composite foam exhibits a 207 % improvement in compressive strength compared to pristine cellulose foam. To impart multifunctionality, an inorganic–organic surface encapsulation strategy is applied, achieving excellent hydrophobicity (water contact angle: 133.9°), self-extinguishing flame-retardancy, and biodegradability. Practical evaluations, including high-altitude drop tests and transport packaging simulations, confirm the suitability of foam for protective applications. This work offers a scalable and sustainable pathway for engineering high-performance biomass-based foams, advancing the development of eco-friendly alternatives for transport and packaging.

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