Tunicate cellulose nanocrystals reinforced nanocomposite hydrogels comprised by hybrid cross-linked networks.

Cellulose nanocrystals are considered as promising biomass nanofillers for polymeric hydrogels, but poor interface compatibility between cellulose nanocrystals and hydrogel matrix usually reduces their reinforcement effect. Here, we reported a novel interface compatible nanocomposite hydrogel prepared by introducing quaternized tunicate cellulose nanocrystals (Q-TCNCs) into chemically cross-linked poly (acrylic acid) (PAA) networks. Q-TCNCs acted as both nanofillers and physical cross-linkers in the PAA networks, and the electrostatic interaction between the positive charges of Q-TCNCs and negative charges of PAA chains improved their interface compatibility. The nanocomposite hydrogels exhibited controllable swelling ratio and pH-sensitive swelling behaviors. The mechanical properties of hydrogels significantly increased after incorporation of Q-TCNCs. Moreover, the nanocomposite hydrogels exhibited partly recoverable ability due to the presence of reversible electrovalent bonds in the hydrogel networks.