Ultra-low shrinkage chitosan aerogels trussed with polyvinyl alcohol

Naturally-derived materials have attracted numerous attention owing to a unique native set of properties, but the significant shrinkage of biomass aerogel, from its final wet gel to aerogel, remains a formidable challenge. Here we explore a strategy based on supramolecular interaction and covalent crosslinking to overcome the inherent large shrinkage of chitosan aerogel, by reinforcing its molecular-level structure. The introduction of linear polyvinyl alcohol (PVA) chains can adequately interpenetrate with crosslinked chitosan chains to form strong intermolecular network architecture. Chitosan aerogel trussed with PVA enables to be readily fine-tuned, simultaneously giving rise to nano-sized cellular voids inside the aerogel. Chitosan aerogel obtained shows good heat insulation, applicable compressive property and exceptional processing feature of special-shaped components. We also find an emergent phenomenon that the addition of PVA may steer desirable orientation shrinkage, and linear elasticity at low strain in terms of chitosan aerogel.