Browsing by Author "Eronen, Heli"

In this thesis, thermoresponsive poly(N-acryloyl glycinamide-co-methacrylic acid) (P(NAGA-co-MAA)) microgels were synthesized via surfactant stabilized free radical precipitation polymerization. Also, PNAGA microgel was synthesized as reference. The upper critical solution temperature (UCST) behavior of the microgels was tuned by changing the molar ratio of the monomers in the copolymer. The phase transition behavior of the formed microgel particles were characterized with NMR spectroscopy, microcalorimetry, turbidimetry and light scattering. It was observed that both PNAGA and P(NAGA-co-MAA) microgels display UCST type temperature response. However, in neutral pH, the phase transition of the copolymer gels was prevented due to the deprotonated acid groups of MAA. Hence, all the measurements were made in pH 3, below the pKa of MAA. The phase transition became sharper when the amount of MAA repeating units was increased in the copolymer. Also, the phase transition temperature of the copolymer gels increased when the amount of MAA was increased. In addition to phase transition behavior studies, the reactivity ratios of the monomers were studied during polymerization to analyze the structure of the forming copolymer gels. It was concluded that, as the both monomers had similar reactivity rates, statistical random copolymer gels are formed.