Synthesis of Environmental Sensitive Core-Shell Composites in Supercritical Carbon Dioxide
Date Issued
2011
Date
2011
Author(s)
Hsiao, Yu-Chen
Abstract
In this study, we demonstrate a one-step copolymerization to synthesis multi-responsive hydrogels with core-shell structures using scCO2 as reaction medium. In this case, N-isopropylacrylamide (NIPAM) was copolymerized with N-vinyl-2-pyrrolidinone (VPL) to form temperature-sensitive cores, and a synthetic graft copolymer, poly(dimethylsiloxane)-g-polyacrylate (PDMS-g-PAA), serves as pH-sensitive shells. PDMS-based materials, which have high chain flexibility are soluble in CO2, and offer extra properties such as physiological inertness, good blood compatibility, thermal and oxidative stability, and mechanical integrity to the composites. The assistance of PDMS-g-PAA features vitally in the process as the surfactant, which stabilizes the polymer particles sterically in the dispersion polymerization, and as the contributor of additional functionality to the final product. Therefore, the sensitivity of pH and temperature can be tuned individually. In this study, the structure of copolymers, the morphology of composites, and the influence of the impregnation of hydrophilic monomers, cross-linker concentration, reaction time, and conducting pressure are investigated. Furthermore, we examined applications in incorporation and in vitro release of drug.
Subjects
supercritical carbon dioxide
NIPAM
VPL
PDMS-g-PAA
micelle
temperature-sensitive
pH-sensitive
drug release
Type
thesis
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