Aerogels made of nanocellulosic materials are interesting new materials with highly porous and flexible structure. In addition, its surface properties can be easily modified for diverse applications due to the abundant hydroxyl groups in cellulose chain. However, typical nanocellulosic aerogels are formed by interfibrillar hydrogen bonds and these fiber networks are easily destroyed by water. This weakness in wet strength is a limitation for the various applications of nanocelllosic aerogels.<br/> In this research, we treated cellulose nanofibrils (CNF) with maleic acid and hypophosphite. Firstly, maleic acid was reacted with water dispersed CNF to form ester linkage. Then, hypophosphite was added into the maleic acid-modifiedCNF suspension and the suspension was quickly frozen using liquid nitrogen. After freeze drying, CNF aerogel was prepared, where cross-linkage of cellulose chain was formed by the reaction between hypophosphite and maleic acid attached to cellulose. With these two-step cross-linking reactions, covalent cross-linked CNF aerogel with water absorbency was produced. Moreover, cross-linked CNF aerogel showed shape recovery characteristics after compressive deformation in wet state. Shape recovery of cross-linked CNF aerogel was evaluated by two-cycle compressive test and it was shown that the performance of the cross-linked CNF was about 2.5 times higher than that of untreated CNF aerogel.

Preparation of cross-linked cellulose nanofibril aerogel with water absorbency and shape recovery

249th National Meeting (2015)

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