Institute of Chemistry, University of Campinas, Caixa Postal 6154, Campinas, SP 13083-970, Brazil.
J Phys Chem B. 2012 Mar 1;116(8):2376-84. doi: 10.1021/jp2103403. Epub 2012 Feb 17.
The presence of acid groups with different pK(a) values in the anionic copolymer poly(4-styrene sulfonic acid-co-maleic acid), P(SS-Ma), allowed the preparation of complex salts with a variable fraction of anionic groups neutralized by cationic surfactant in the copolymer via controlled titration with hexadecyltrimethylammonium hydroxide, C(16)TAOH. Two new complex salts were selected for detailed phase studies, C(16)TA(2)P(SS-Ma) and C(16)TA(3)P(SS-Ma), where both had 100% charged styrene sulfonate groups, but the fraction of charged carboxylate groups on the polyion was 50% or 100%, respectively. These complex salts thus contained both hydrophobic (styrene sulfonate) and hydrophilic (carboxylate) charged groups, and the ratio between the two could be altered by titration. These features were found to have consequences for the phase behavior in water and in ternary mixtures with water and n-alcohols for the two complex salts, which differed compared to complex salts containing homo- or copolyions with only carboxylate or styrene sulfonate charged groups. For both complex salts, binary mixtures with water produced, in the dilute region, two isotropic phases in equilibrium, the bottom (concentrated) one displaying increasing viscosity with increasing concentration. For the complex salt C(16)TA(2)P(SS-Ma), there was evidence of micellar growth to form anisometric aggregates at high concentrations. For the C(16)TA(3)P(SS-Ma) complex salt, this was not observed, and the isotropic phase was followed by a narrow region of cubic phase. In both cases, concentrations above ca. 60 wt % produced a hexagonal phase. For ternary mixtures with n-alcohols, the general trend was that a short-chain alcohol such as n-butanol acted as a cosolvent dissolving the aggregates, whereas with n-decanol, a cosurfactant effect was observed, inducing the formation of lamellar phases. Visual inspection (also between crossed polarizers), small angle X-ray scattering (SAXS) and diffusion nuclear magnetic resonance (NMR) were used in these studies.
在阴离子共聚物聚（4-苯乙烯磺酸-co-马来酸），P（SS-Ma）中存在不同 pK(a) 值的酸基团，允许通过用十六烷基三甲基氢氧化铵，C(16)TAOH 进行控制滴定，用阳离子表面活性剂中和共聚物中阴离子基团的可变分数，制备具有可变分数的复杂盐。选择了两种新的复合盐进行详细的相研究，C(16)TA(2)P(SS-Ma)和 C(16)TA(3)P(SS-Ma)，它们都具有 100%带电荷的苯乙烯磺酸盐基团，但聚电解质上带电荷的羧酸盐基团的分数分别为 50%或 100%。这些复合盐因此既包含疏水性（苯乙烯磺酸盐）又包含亲水性（羧酸盐）带电荷基团，并且这两个基团之间的比例可以通过滴定来改变。这些特性对两种复合盐在水中以及与水和正醇的三元混合物中的相行为产生了影响，与仅含有羧酸盐或苯乙烯磺酸盐带电荷基团的同聚物或共聚物的复合盐相比，这两种复合盐有所不同。对于这两种复合盐，在稀溶液区与水的二元混合物产生了两种平衡的各向同性相，底部（浓缩）相的粘度随浓度的增加而增加。对于复合盐 C(16)TA(2)P(SS-Ma)，有证据表明存在胶束生长，形成各向异性聚集物在高浓度下。对于 C(16)TA(3)P(SS-Ma)复合盐，没有观察到这种情况，各向同性相之后是一个狭窄的立方相区。在这两种情况下，浓度高于约 60wt%都会产生六方相。对于与正醇的三元混合物，一般趋势是短链醇，如正丁醇作为助溶剂溶解聚集物，而对于正癸醇，则观察到助表面活性剂的作用，诱导层状相的形成。这些研究中使用了目视检查（也在交叉偏光镜之间）、小角 X 射线散射（SAXS）和扩散核磁共振（NMR）。
