Anisotropic Single-Domain Hydrogel with Stimulus Response to Temperature and Ionic Strength

Hydroxypropyl cellulose (HPC) is a derivative of cellulose with lyotropic liquid crystal property and thermochromism. We took advantage of HPC and combined it with a thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel to fabricate an anisotropic single-domain hydrogel by mechanical shearing. The prepared long-range ordered HPC–PNIPAM hydrogels show bright and uniform interference colors between crossed polarizers, which are stimulus-responsive to both temperature and ionic strength. In particular, the oriented HPC–PNIPAM hydrogel has a wide thermoresponsive range which could be adjusted by the HPC and PNIPAM content in the hydrogel, providing a good solution to the narrow or fixed temperature sensing range of hydrogels.