N-异丙基丙烯酰胺共聚物的温敏性

采用自由基水溶液聚合方法制备出了N-异丙基丙烯酰胺(N IPA)温敏共聚物P(AM-N IPA);首次在P(AM-N IPA)结构中引入丙烯酸钠(N aAA)单体结构单元,合成了离子型共聚物P(AM-N IPA-N aAA);考察了共聚物P(AM-N IPA)和P(AM-N IPA-N aAA)溶液温敏性的影响因素;分别采用荧光光谱分析法以及乌氏黏度计稀释法对共聚物溶液温敏机理进行了研究。结果表明,不同共聚单体的配比以及单体含量对共聚物溶液低临界溶解温度(LCST)均有显著影响;当温度高于共聚物低临界溶解温度时,共聚物分子链上的疏水基团的缔合作用增强,导致疏水聚集结构的形成,聚合物分子链发生去溶剂化作用,在共聚物稀溶液中表现为线团收缩,在共聚物亚浓溶液中表现为共聚物分子间聚集发生相分离。

THE STUDIES ON THE TEMPERATURE SENSITIVE OF N-ISOPROPYLACRYLAMIDE COPOLYMER

The thermosensitive water-soluble copolymers P(AM-NIPA) of acrylamide(AM) and N-isopropylacrylamide(NIPA) were synthesized by free radical aqueous solution copolymerization,and the ionic copolymer P(AM-NIPA-NaAA) was prepared by incorporating the third monomer sodium acrylic acid(NaAA) to the molecule structure of P(AM-NIPA).The thermosensitive mechanism of copolymer solution was studied by the fluorescence Spectrum and intrinsic viscosity.The result shows that the proportion of monomer and monomer amount in the copolymer has notable effect on the low critical solution temperature(LCST) of the copolymer solution.The LCST of copolymer solution increases with the content of AM or AA in the copolymer.When the temperature of copolymer solution reaches to the low critical solution temperature,the polarity of media around the pyrene probe decreases sharply,which causes the congregating of the hydrophobic structure of the copolymer.Molecule chains of polymer take place desolvent,which causes shrink of clew in the rare solvent of copolymer and phase separate in the dense solvent of copolymer due to congregating of copolymer.