Preparation of Thermo-/pH-Responsive shell-crosslinked Nanoparticles and their Structural Characterization

• Main Authors: Fa Fen Tang, 湯發奮
• Other Authors: 邱信程
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/76490822262584529452

碩士 === 國立中興大學 === 化學工程學系所 === 94 === Thermo/pH-responsive nanogels were synthesized by radical polymerization of the methacryloyl ethyl acrylate (MEA) moieties of the graft copolymer comprising acrylic acid (AAc) and MEA units as the backbone and poly(N-isopropylacrylamide) (PNIPAAm) and mPEG as the grafts in micelle form in aqueous phase at high temperature. The nanogels with core-shell structure exhibit highly increased stability in comparison with their micelle precursors and temperature-dependent swelling behavior at pH below 5.0. The swelling also significantly changes in response to pH alteration, the extent being dependent on the cross-linking density of the nanogels. The raising ratio of solid/liquid-like core structure in the nanogels with increasing temperature is attributed to the continual dehydration of the PNIPAAm grafts. In addition, the increase in the degree of AAc residue dissociation with increasing pH raises the liquid-like core fractions due to the swelling of hydrogel layer and disruption of interchain hydrogen bonding. At pH 7, the more hydrated core inside the nanogels with surrounding dissociated PAAc hydrogel layer significantly reduces the interchain hydrophobic interaction of PNIPAAm grafts with increasing temperature, inducing the formation of hollow-like structure at high temperature.