Effect of nanofillers on carboxymethyl cellulose/hydroxyethyl cellulose hydrogels

The effect of hydrophilic nanoparticles (oxidized cellulose nanocrystals (CNC) and montmorillonite nanoclay) on the properties of a sodium carboxymethylcellulose (CMC)/hydroxyethylcellulose (HEC) hydrogel system was investigated. Visually, the CNC reinforced cellulosic hydrogel-composites were transparent over all CNC loadings, whereas those reinforced with organoclay were opaque even at low clay loadings despite the nanoparticles being well dispersed. Incorporation of CNC into the cellulosic hydrogels led to an increase in the compressive modulus of CNC-hydrogel composites, but a corresponding decrease in the swelling ratio. However, the addition of CNCs enabled a reduction in the amount of cross-linker required to obtain a given compressive modulus and swelling behavior. It was observed that the surface charge density of the CNCs had no significant effect on the compression modulus or swelling behavior of the CMC/HEC hydrogel composites. By contrast, the organoclay reinforced CMC/HEC hydrogels did not show any trend in compression modulus or swelling ratio with organoclay content.