水溶液中聚乙烯基吡咯烷酮与十二烷基硫酸钠的相互作用机理

Mechanism on the Interaction Between Poly(N-Vinyl Pyrrolidone) and Sodium Dodecyl Sulfate in Aqueous Solutions

利用黏度、电导、表面张力和荧光光谱实验手段研究了聚乙烯基吡咯烷酮(PVP)和十二烷基硫酸钠(SDS)在水溶液中的相互作用,发现对SDS来说存在三个不同的特征浓度:临界聚集浓度(CAC)、CAC2和高分子饱和浓度(PSP)。实验结果表明,PVP和SDS在水溶液中的相互作用可以用类似于描述聚电解质和带相反电荷表面活性剂之间相互作用的两阶段模型解释:初始阶段(CSDS>CAC),带负电荷的SDS分子主要以单个的方式吸附到PVP带正电的侧基上;第二阶段(CSDS>CAC2),SDS分子通过疏水相互作用以协同的方式吸附到PVP分子链上形成胶束,在浓度为PSP时达到饱和。

The interaction of poly（N-vinyl pyrrolidone）（PVP） with sodium dodecyl sulfate （SDS） in aqueous solution was investigated using viscosity,conductivity,surface tension and steady-state fluorescence measurement.It has been found that three critical concentrations of SDS,referred to as critical aggregation concentration（CAC）,CAC2 and polymer saturation point（PSP） respectively,can be detected.The experimental results indicate that the mechanism on the interaction of PVP with SDS in aqueous solution can be explained by the two-stage model which is originally suggested for the system of polyelectrolyte with oppositely charged surfactants in aqueous solution.In the initial stage corresponding to CSDSCAC,SDS molecules with the anionic head-groups bind to the ＂cationic＂ side groups of PVP chain individually due to electrostatic attractive interaction.In the second stage corresponding to CSDSCAC2,SDS molecules can bind to polymer chains cooperatively to form polymer-bounded micelles mainly by the adjacently hydrophobic interaction and become saturated at PSP.