| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 95 === PNIPAAm, PNIPAAm-AAm copymer and their nanocomposites with MMT were successfully fabricated by emulsifier-free emulsion polymerization. The exfoliated morphology was confirmed by the TEM microscopy and X-ray diffraction patterns. The LCST would be increased by adding MMT in the PNIPAAm series slightly, but decreased in PNIPAAm-AAm series. Besides, MMT indeed influenced the rate of phase transformation.
Due to the change of morphology, the changes of physical properties were expected. The visible light absorption of PNIPAAm-AAm nanocomposite films was increased with the MMT content. This was due to the fact that the visible light would be scattered by MMT nanoplatelets. Molecular weight was also decreased in the presence of MMT. In PNIPAAm-AAm copolymer series, the glassy transition temperature was increased with the MMT content due to the molecular chains were trapped by nanoplatelets. However, in PNIPAAm series, a reverse result was observed. This may be due to that the presence of MMT might interfere with the formation of hydrogen bonding.
Furthermore, we applied these new materials to drug delivery system. From the toxicity measurement, only PNIPAAm-AAm series had a trace of toxicity, but the toxicity could be diminished in the presence of MMT. PNIPAAm and PNIPAAm-AAm-GMA were innocuous to yeast. In order to maintain the shape of nanocomposite films in water, crosslinked PNIPAAm-AAm-GMA series were adopted for the drug releasing and swelling ratio experiments. The rate of drug releasing and the diffusion coefficient were decreased with the MMT content, because the presence of MMT nanoplatelets in the matrix could provide the tortuosity to the diffusion path. In the swelling experiment, the swelling ratio increased with the content of MMT. However, with higher MMT content, the specimens were more sustainable in the water.
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