| Summary: | 碩士 === 國立中興大學 === 化學工程學系 === 93 === Graft copolymers comprising monomeric units of acrylic acid (AAc) and methacryloyl ethyl acrylate (MEA) as the copolymer backbone and poly (N-isopropylacrylamide) (PNIPAAm) and monomethoxy–poly (ethylene glycol) (mPEG) as grafts were obtained from partial transesterification of poly(N-acryloxysuccinimide) (polyNAS) with 2-hydroxyethyl ethacrylate (HEMA) and aminolysis with semitelechilic PNIPAAm-NH2 and PEG-NH2, respectively, followed by full hydrolysis of the remaining NAS residues into AAc in aqueous phase. The structure of the graft copolymers was established by 1H NMR spectroscopy. The graft copolymers underwent self-aggregation into micelle structure with increasing temperature above their critical micelle temperatures (CMTs) in aqueous phase. Microgels were prepared by treatment of polymer aqueous solutions of 1.0 mg/mL at 90 ℃ for two weeks, followed by radical polymerization of the MEA moieties at 60 ℃ for 48h using ammonium pexodisulfate (APS) as the initiator. The approach to preparing microgels by heating the polymer aqueous solution at 90 ℃ prior to the radical polymerization aims to prevent polymeric micelles from serious aggregation. Extensive extent of intermolecular physical entanglement and hydrogen bond formation, however, led to formation of compact structure of polymeric particles. The microgels exhibited temperature-responsive swelling behavior at low pH. However, reduced response to the temperature changes was observed with increasing pH probably due to the increased degree of ionization of the AAc units and hydrophilicity of polymeric particles.
|
|---|
