Lynch Iseult, Sjöström Jesper, Piculell Lennart
Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, S-22200 Lund, Sweden.
J Phys Chem B. 2005 Mar 10;109(9):4258-62. doi: 10.1021/jp045279a.
The interactions between charged alkylacrylamide gels of varying hydrophobicity and charge density and the oppositely charged surfactant hexadecyltrimethylammonium (C16TA+) have been investigated to determine the conditions necessary to induce excess surfactant binding (beyond charge neutralization) and resolubilization of the polymer-surfactant complex. In all cases, an initial gel collapse occurred due to neutralization of the charges in the gel, and the volume of the collapsed gel was smaller than that of the corresponding neutral gel at the same surfactant concentration, as a result of the formation of interchain micellar cross-links. For gels containing neutral repeating units that were found previously to bind C16TA+, a subsequent sharp reswelling of the gel network occurred, beginning at a critical surfactant concentration called the cac(2). The reswelling is due to binding of excess surfactant, which results in the gels becoming recharged. For gels whose neutral repeating units do not bind C16TA+, there was no reswelling behavior (no cac(2)), but there was a gradual increase of the swelling back to that of the equivalent neutral gel with increasing surfactant concentration. The results are interpreted in terms of the expected surfactant binding isotherm.
研究了不同疏水性和电荷密度的带电烷基丙烯酰胺凝胶与带相反电荷的表面活性剂十六烷基三甲基铵（C16TA+）之间的相互作用，以确定诱导过量表面活性剂结合（超过电荷中和）和聚合物-表面活性剂复合物再溶解所需的条件。在所有情况下，由于凝胶中电荷的中和，最初会发生凝胶塌陷，并且在相同表面活性剂浓度下，塌陷凝胶的体积小于相应中性凝胶的体积，这是链间胶束交联形成的结果。对于先前发现能结合C16TA+的含有中性重复单元的凝胶，凝胶网络随后会发生急剧再膨胀，从一个称为cac(2)的临界表面活性剂浓度开始。再膨胀是由于过量表面活性剂的结合，这导致凝胶重新带电。对于其中性重复单元不结合C16TA+的凝胶，没有再膨胀行为（没有cac(2)），但随着表面活性剂浓度的增加，溶胀会逐渐增加至等效中性凝胶的溶胀程度。根据预期的表面活性剂结合等温线对结果进行了解释。
