Preparation and characterization of thermal/pH-sensitive hydrogel from carboxylated nanocrystalline cellulose

Carboxylated nanocrystalline cellulose (CNCC) was used as a matrix material for the preparation of N-isopropyl acrylamide-based thermal/pH sensitive hydrogels. The resulting hydrogels’ structure, morphology, thermal/pH-sensitive properties, swelling behavior and mechanical properties were investigated. The results indicated that the CNCC/PNIPAAm hydrogels exhibited the pH- and temperature-sensitivity. From its stress–strain curves, the hydrogels’ stiffness increased obviously from the change of yield point when the amount of CNCC was increased. Scanning electron microscopy (SEM) supported the hypothesis that the added CNCC became an integral network of the hydrogels, which is responsible for the observed thermal/pH sensitivity and the improved strength.