十二烷基氧丙基-β-羟基三甲基溴化铵与阴离子聚电解质的缔合作用

The Binding of Dodecyloxypropyl-β-hydroxyltrimethyl AmmoniumBromide on Different Polyanions

运用电势滴定和表面张力法研究了阳离子表面活性剂十二烷基氧丙基－β－羟基三甲基溴化铵(Ｃ１２ＮＢｒ)与疏水修饰的丙烯酸类聚合物ＡＭＢ、ＡＭＢＡ及柔性阴离子聚合物ＨＰＡＭ的结合等温线．结果表明,Ｃ１２ＮＢｒ与ＨＰＡＭ缔合过程中有明显的协同特征,即结合量突然上升,并且在很窄的表面活性剂浓度范围内达到饱和．Ｃ１２ＮＢｒ与ＡＭＢ或ＡＮＢＡ的相互作用是非协同性的,结合等温线经历了较宽的浓度范围,没有明显的临界聚集浓度,结合量较小,此现象归结为这类聚合物具有较高的疏水性．

The binding of cationic surfactant dodecyloxypropyl-β-hydroxyltrimethyl ammonium bromide(C12NBr) on different polyanions, such as hydrolytic polyacrylamide (HPAM), hydrophobic modifiedpolyacrylates(AMB, AMBA), were investigated by using a potentiometric technique and surface tensionmeasurements at (30.0±0.1)℃. The binding isotherms of C12NBr to HPAM show a cooperative charac-teristic nature: the binding suddenly occurs and is soon saturated within a very narrow concentration range.The sudden onset of binding is referred to as the critical aggregation concentration(cac), in analogy withcmc in micelle formation. The cac value, however, is 1.5 orders of magnitude lower than the cmc. Thebinding of C12NBr to hydrophobic modified polyelectrolytes has begun at very low cf and show noncoopera-tive. For the two polyelectrolytes AMB and AMBA, a slow and continuous increase in β with the increaseof cf is observed. This is caused by the presence of hydrophobic microdomains formed by the polyelec-trolytes concentration of surfactant. The surface tension isotherms of C12NBr/HPAM exhibit two aggrega-tion concentration cT1, cT2, and CT1<cmc<CT2. But from the surface tension of mixture of C12NBr and hy-drophobic modified polyelectrolytes, we get a 1ower cmc. It is because that C12NBr molecules interact withpolymer by electrostatic on air-solution interface, and form ordered compact structure of surfactant-poly-mer complex.