Strong, tough, ionic conductive, and freezing-tolerant all-natural hydrogel enabled by cellulose-bentonite coordination interactions

Cellulose based ion conductive hydrogels are emerging materials for application in flexible electronics but achieving simultaneously high conductivity and good mechanical properties remains challenging. Here, the authors propose a supramolecular engineering strategy to strengthen cellulosic hydrogel and to improve simultaneously its ionic conductivity and freezing tolerance. Ionic conductive hydrogels prepared from naturally abundant cellulose are ideal candidates for constructing flexible electronics from the perspective of commercialization and environmental sustainability. However, cellulosic hydrogels featuring both high mechanical strength and ionic conductivity remain extremely challenging to achieve because the ionic charge carriers tend to destroy the hydrogen-bonding network among cellulose. Here we propose a supramolecular engineering strategy to boost the mechanical performance and ionic conductivity of cellulosic hydrogels by incorporating bentonite (BT) via the strong cellulose-BT coordination interaction and the ion regulation capability of the nanoconfined cellulose-BT intercalated nanostructure. A strong (compressive strength up to 3.2 MPa), tough (fracture energy up to 0.45 MJ m(-3)), yet highly ionic conductive and freezing tolerant (high ionic conductivities of 89.9 and 25.8 mS cm(-1) at 25 and -20 degrees C, respectively) all-natural cellulose-BT hydrogel is successfully realized. These findings open up new perspectives for the design of cellulosic hydrogels and beyond.