利用核磁共振技术对N-异丙基丙烯酰胺共聚微凝胶去溶胀过程的研究

利用变温核磁共振技术考察了N异丙基丙烯酰胺（NIPAM）与二缩三乙二醇单甲基丙烯酸酯（TREGMA）共聚形成的温敏性微凝胶p（NIPAM-co-TREGMA）的去溶胀行为。首先测定了微凝胶在不同温度下的变温核磁1H谱,结果表明,微凝胶发生去溶胀时的体积相转变温度（VPTT）随着亲水侧链—（—OCH2CH2）—3OH含量的增加而升高,且去溶胀时亲水性侧链从微凝胶网络内部移到网络表面,在表面发生富集。然后进一步考察了温度升高时不同质子自旋晶格弛豫时间（T1）的变化情况,根据T1的变化趋势从微观角度分析了微凝胶发生去溶胀时的分子间作用。

Investigation on the Deswelling Behavior of N-isopropylacrylamide Copolymer Microgels by NMR Technique

Variable-temperature nuclear magnetic resonance （NMR） technique was employed to investigate the deswelling behavior of copolymer type temperature-sensitive poly （isopropyl-acrylamide- co- triethyle neglycol monomethacrylate） （p（NIPAM-co-TREGMA）） microgels in two ways. Firstly variable-temper ature 1H NMR spectra were recorded at different temperature. It shows that incorporation of hydrophilic side chains -（-OCH2CH2-）2-OH causes the volume-phase transition temperatures （VPTTs） of pNI PAM microgels to shift to higher temperature. Then further investigation on the variable-temperature 1H NMR spectra reveals that hydrophilic side chains-（-OCH2CH2-）3-OH protrude to the outer of the network and enrich in the surface of the microgels after deswelling. Then the changing trends of protonlattice relaxation time （T1） against temperature of different protons were further inve lar interactions during the volume-phase transition were analyzed according to the changing stigated. trends of The molecu T1.