Solid-state NMR study on the dynamics of thermo-sensitive cellulose/poly(N-isopropylacrylamide) composite hydrogel

The cellulose/poly(N-isopropylacrylamide) (PNIPAM) composite thermo-sensitive hydrogel was prepared by interpenetrating polymer network (IPN) approach. Various solid-state nuclear magnetic resonance (NMR) methods including ¹³C cross polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR), ¹³C quantitative cross polarization (QCP) NMR, static ¹H NMR and ¹H filtering-spin diffusion NMR experiments were performed to analyze the structure, content, property and dynamics of the composite thermo-sensitive hydrogel. The results show that the cellulose/PNIPAM composite hydrogels have obvious temperature sensitivity. Cellulose molecules are relatively rigid while PNIPAM molecules are flexible. The space between cellulose and PNIPAM chains are very close.