EFFECT OF PHBV CONTENT ON THE TRANSPARENCY AND SWELLING BEHAVIOR OF POLYMER/HECTORITE NANOCOMPOSITE HYDROGEL

As a kind of novel biopolymer material with good biodegradability and biocompatibility, poly(β-hydroxybutyrate-co-valerate)(PHBV) was introduced into organic/inorganic network structure of nanocomposite hydrogels prepared by in-situ free-radical polymerization based on monomer N-isopropylacrylamide(NIPAM) and physical cross-linker hectorite. As viewed from appearance of the hydrogels, obvious change occurred from transparent to white with the increase of PHBV content, which reflects the structural shift from homogeneity to inhomogeneity. The swelling ratio and swelling kinetics of thermo-sensitive poly(NIPAM/PHBV/Hectorite) hydrogels with different PHBV content was investigated by gravimetric method. It was found that the incorporation of PHBV decreases the swelling ratio of pure poly(NIPAM/Hectorite) hydrogels on account of hydrophobicity of PHBV. Furthermore, in the case of swelling kinetics, the result of linear regression shows that relaxation of polymer chains of the hydrogels controls the swelling process.