Low density methacrylated pea, corn, and tapioca starch covalent cryogels with excellent elasticity and water/oil absorption capacity.

Porous starch materials are promising in several applications as renewable natural biomaterials. This study reports an approach combining methacrylation of starch and chemical crosslinked cryogelation to fabricate highly elastic macroporous starch (ST-MA) cryogels with impressed water/oil absorption capacity and wet thermal stability among starch based porous materials. Five different types of starch, including pea, normal corn, high amylose corn, tapioca, and waxy maize starch with different amylose content, have been studied. The methacrylation degree is not related with amylose content. All cryogels exhibited excellent compressive elasticity enduring 90 % deformation without failure and good robustness in cyclic tests. The ST-MA cryogels from pea starch exhibited the highest Young's modulus and compressive strength among five types of starch. These covalent cryogels exhibit high wet-thermal stability and enzymatic hydrolysis stability, while still are biodegradable. The dry ST-MA sponges (2 wt%) showed outstanding liquid absorption capacity, absorbing ~40 folds (g/g) of water or ~ 36 folds (g/g) of oil respectively. All types of starch have similar liquid absorption performance. This study provides a universal approach to fabricate highly elastic covalent starch macroporous materials with impressed liquid absorption capacity and outstanding stability, especially wet-thermal stability, and may expand their applications.