激光光散射研究聚(N-异丙基丙烯酰胺)单链及其智能凝胶微球在水中的相变(下)  

Light Scattering Study of Phase Transition of A Single Chain and Smart Microgel Particles of Poly( N isopropylacrylamide) in Water

作　　者：吴奇[1,2] 汪晓辉[1,2] 高均[1,2] 

机构地区：[1]中国科学技术大学化学物理系科学院选键化学开放实验室 [2]香港中文大学化学系

出　　处：《高分子通报》1998年第4期1-9,共9页Polymer Bulletin

摘　　要：（接上期）２聚（Ｎ－异丙基丙烯酰胺）微凝胶在水中的体积相变２．１理论部分凝胶体积相变热力学：聚合物凝胶的溶胀和蜷缩可以用膨胀因子α＝（Ｖ／Ｖ０）１／３＝（ΦＴ／ΦΘ）１／３来表征，其中ΦΘ的ΦＴ分别是温度Θ和Ｔ下凝胶网络的体积分数。在平均场理论中，中...Using a combination of static and dynamic light scattering,we systematically studied the coil to globule and globule to coil transitions of a single linear poly( N isopropylacrylamide)(PNIPAM) chain and the volume change of spherical PNIPAM microgels in water.We made,for the first time,the conformation change of individual homopolymer chains from a coil to a fully collapsed stable single chain globule and confirmed the existence of the crumpled coil and the molten globule states between the random coil and the fully collapsed globular states.The study of the coil to globule transition kinetics rejects the previously suggested high chain knotting density inside the globule.Our result also indicated that even in its fully collapsed state,the globule and the microgel particle still contain 66% and 70% water,respectively.The study of interaction between the PNIPAM microgel and surfactant suggested a new swelling and shinking mechanism different from the previously proposed hydrophobic interaction.Moreover,our NMR results showed,for the first time,that surfactant molecules are able to form micelles in presence of the gel network even the surfactant concentration is much lower than its critical micelle concentration.A comparison of the phase transitions of the linear chains and microgels revealed that previously observed discontinuous volume change in bulk PNIPAM gels is due to the imbalance between the bulk shear module and the internal stress originated from the inhomogeneous shrinking,which is different from the theoretically predicted discontinuous volume phase transition.

关 键 词：PNIPAM 凝胶 微凝胶 相变 水 智能凝胶 

分 类 号：O632.63[理学—高分子化学]