Effects of Silica Content on the Properties of Poly(N-isopropylacrylamide)/Silica Nanocomposite Hydrogels

摘要

Poly(N-isopropylacrylamide) is a representative thermosensitive polymer, whose hydrogels have broad applications. But poly(N-isopropylacrylamide) hydrogels are weak and brittle. To get higher strength hydrogels, in this paper, silica sol was utilized as nanoparticle reinforcer source to construct poly(N-isopropylacrylamide)/silica nanocomposite hydrogels by in situ polymerization. By means of scanning electron microscopy, nano-silica was found dispersed evenly on the surface of PNIPA polymer network. Encouragingly, the compression strength of composite hydrogels have been enhanced more than 60% owing to the introduction of nano-silica. Obviously, the more silica sol this composite hydrogels contain, the longer gelation time they obtain. Compared to pure PNIPA hydrogels, nanocomposite hydrogels have faster deswelling speed at high temperature. And the lower critical solution temperature of nanocomposite hydrogels with different content of silica hydrogels was found between 33.5°C to 34.5°C. Because silica sol is facial to composite with hydrogel, this study provides a simple way for nanocomposite reinforced hydrogels preparation.