Studies on Association-dissociation and Interaction of Hydrophilic, Reversible Colloids

我们对盐诱导的离子表面活性剂胶束的球-棒转变的研究已经扩展到具有十四基和十六基的烷基三甲基卤化铵的卤化钠水溶液，卤化物是氯和溴。用光散射法测定了胶束的相对分子质量。球棒转变的阈值盐浓度较低，因为烷基链较长，而且反离子是溴离子而不是氯离子。棒状胶束的胶束相对分子质量与盐浓度的依赖关系主要取决于反离子结合的程度。测定了十二烷基二甲基氯化铵氯化钠水溶液的超速离心沉降，观察到棒状胶束与球形胶束伴生的纹影结构特征，并具有较强的浓度依赖性。对难溶于水的染料，棒状胶束的增溶能力约为球形胶束的两倍。测量了二甲基油胺氧化物水溶液在盐酸和/或氯化钠存在下的光散射，观察到了反常的角度依赖关系，表明当棒状胶束的相对分子质量在100万左右时，外部干扰很强。用圆环二向色性测量的方法研究了阳离子表面活性剂对阴离子多肽--聚L-谷氨酸钠和聚S-羧甲基L-胞苷钠构象的影响。十二烷基氯化铵在水溶液中可分别诱导-螺旋构象和-构象，但其N-甲基取代减弱了这种诱导作用。一般说来，烷基长于庚基的烷基氯化铵可以诱导聚L-谷氨酸的-螺旋构象，但其诱导-S-羧甲基-L-半胱氨酸构象的作用有一定的复杂性。

Our investigation on the salt-induced sphere-rod transition of micelles of ionic surfactants has been extended to aqueous sodium halide soultions of alkyltrimethylammonium halides having teragecyl and cetyl groups, Halides are chloride and bromide. Micelle molecular weight was been measured by light scattering. The threshold salt concentration of the sphere-rod transition is lower, as the alkyl chain is longer and as the counterion is bromide rather than chloride. The dependence of micelle molecular weight of rodlike micelles on the salt concentration is primarily determined by the degree of counterion binding. Ultracentrifugal sedimentation of aqueous NaCl solutions of dodecyldimethylammonium chloride has been measured, and charateristic feature is observed on the schlieren pattern of rodlike micelles, accompanying spherical micelles, and having strong concentration dependence of sedimentation coefficient itself. Solubilization power toward a water-insoluble dye is about twice larger for rodlike micelles than for spherical micelles.Light scattering from aqueous solutions of dimethyloleylamine oxide in the presence of HCl or NaCl or both has been measured, and anomalous angular dependence is observed, indicating strong external interference, when the rodlike micelle has molecular weight around a million.The effects of cationic surfactants on the conformation of anionic polypeptides, i.e.,sodium poly-L-glutamate and sodium poly-S-carboxymethyl-L-cyteine, have been examined by means of ciruclar dichroism measurements. Dodecylammonium chloride can induce the -helix and the -conformation, respectively, in aqueous solution, but its N-methyl-substitution reduces this induction. Generally, alkylammonium chlorides having alkyl longer than heptyl can induce the -helix of poly-L-glutamic acid, but their effects inducing the -conformation of poly-S-carboxymethyl-L-cysteine are somewhat compli-cated.