PEG-induced lamellar-to-isotropic phase transition in the system of TX-100/n-C8H17OH/H2O.
PEG-induced lamellar-to-isotropic phase transition in the system of TX-100/n-C8H17OH/H2O.
复制标题
DOI：
10.1021/jp808218j
复制
发表时间：
2009-01
期刊：
影响因子：
--
通讯作者：
Lingling Ge;R. Guo;Xiaohong Zhang
中科院分区：
文献类型：
--
作者：
Lingling Ge;R. Guo;Xiaohong Zhang
在分子量为400~20 000的中性水溶性聚合物聚乙二醇(PEG)诱导的TX-100/n-C(8)H(17)OH/H(2)O体系中观察到层状到各向同性的相变。通过(2)H NMR、小角核磁等手段研究了PEG在层状液晶中的位置以及相变过程中层状相微观结构的变化。 X 射线衍射 (SXRD)、流变学、偏光光学显微镜 (POM) 和冷冻断裂透射电子显微镜 (FF-TEM)。基于“溶胀模型”的计算表明，0.92-2.58wt%的PEG2000渗透到两亲物层中，其余部分溶解在水层中。这两种位置都会引起层状到各向同性的相变。 PEG的链长越长，效率越高。此外，在相变发生之前观察到PEG的临界分子量，其中PEG对层状液晶微结构的扰动最为突出。 PEG的临界分子量与水层的厚度无关。对于TX-100/n-C(8)H(17)OH/H(2)O体系，该值为2000。
Lamellar-to-isotropic phase transition is observed in the system of TX-100/n-C(8)H(17)OH/H(2)O induced by neutral water-soluble polymer poly(ethylene glycol) (PEG) with molecular weight ranging from 400 to 20 000. The location of PEG in the lamellar liquid crystal and the microstructure change of the lamellar phase during phase transition are investigated by means of (2)H NMR, small-angle X-ray diffraction (SXRD), rheology, polarized optical microscopy (POM), and freeze-fracture transmission electron microscopy (FF-TEM). Calculations based on the "swelling model" show that 0.92-2.58 wt % PEG2000 penetrates into the amphiphile layer and the rest resolve in the water layer. Both of these two kinds of locations induce the lamellar-to isotropic phase transition. The longer the chain length of PEG, the higher the efficiency is. In addition, a critical molecular weight of PEG is observed before phase transition occurs, with which the disturbance of PEG on the microstructure of lamellar liquid crystal is most prominent. The critical molecular weight of PEG is independent of the thickness of water layer. The value is 2000 for the system of TX-100/n-C(8)H(17)OH/H(2)O.