Synthesis Of Temperature-and PH-sensitive P(MAA-g-DEAM) And Studies On Their Properties

Several different composition temperature- and pH- sensitive poly (methacrylic acid-g-N, N-diethylacrylamide)(P(MAA-g-DEAM)) graft copolymers were synthesized by free-radical copolymerization utilizing macromonomer technique. These synthesized copolymers were with different ratio of DEAM macromonomer and MAA which are temperature- and pH-sensitive monomers respectively. The sensitivities and conformation behaviors of P(MAA-g-DEAM) in aqueous solution were investigated by fluorescence probe technique and UV-vis transmittance measurements, and the investigation was mainly focused on the lower critical solution temperature (LCST) of graft copolymers with different composition at different pH values and on their critical phase-transition pH values at different temperatures. Results showed that the P(MAA-g-DEAM) copolymers had temperature- and pH-sensitivities, and this double sensitivities were independent each other. At the same time these graft copolymers of different composition have the approximately identical critical phase-transition pH values and LCST, respectively. When the DEAM contents were lower, the graft copolymer conformation behavior was like homopolymer PMAA. So we may control the aggregation behavior of the graft copolymer by modulating DEAM contents and pH of the solution.Pyrene labeled P(MAA-g-DEAM) graft copolymers were prepared by free-radical copolymerization, and their conformation changes and aggregating behaviors were investigated by fluorescence label probe technique. Studies showed that the P(MAA-g-DEAM) graft copolymers had temperature- and pH-sensitivities, and the double sensitivities were independent each other. When the DEAM contents were lower, the P(MAA-g-DEAM) graft copolymers conformation behavior was like homopolymer PMAA.The complexation between PDEAM and P(MAA-g-DEAM) graft copolymers were studied by fluorescence technique and UV-vis transmittance measurements. Studies showed that polymer complexes occured between P(MAA-g-DEAM) and PDEAM via hydrogen bonding in aqueous solution at pH lower than 6.5. The complexation between PDEAM and P(MAA-g-DEAM) changed the conformation behaviors of P(MAA-g-...