Thermo‐Moldable Nanocomposite Hydrogels

Abstract

The present paper reports an interesting and versatile thermo‐moldable property of poly(N,N‐dimethylacrylamide)‐clay nanocomposite hydrogels (NC gel). The NC gel can be thermo‐pressed and molded to a desired shape at 80 °C, and the shape can be fixed by cooling to 20 °C. Mechanical test and small‐angle X‐ray scattering demonstrate that the molded NC gel still exhibits high strength with an elastic network structure. Viscoelastic measurements show that with increasing the temperature, the equilibrium shear modulus Ge decreases, and the creep and permanent deformation increases obviously, suggesting a decrease in the cross‐linking density. Ge recovers when the gel is cooled down to room temperature, reflecting the recovery of the cross‐linking density. This thermo‐moldable property is attributed to reversible cross‐linking in such NC gels by changing the temperature. This work provides a facile method to deform or pattern the tough NC gels after synthesis.