多烷基苯磺酸钠水溶液的表面性质

Surface Properties of Sodium Alkylbenzenesulfonates with Additional Side Chains

研究了多烷基苯磺酸钠的结构,特别是侧链碳原子数的增加,对其表面活性的影响,并与其它烷基苯磺酸钠进行了比较.结果表明,随着苯环上侧链碳原子数的增加,多烷基苯磺酸钠的临界胶束浓度(cmc)降低,但侧链上CH2降低cmc的程度远小于主链上CH2的作用.当侧链碳原子数增加时,多烷基苯磺酸钠的饱和吸附量(Γmax)降低,表现出与主链不同的变化规律.从多烷基苯磺酸钠的结构解释了cmc和Γmax的变化规律.

The relationships between the structures of sodium alkylbenzensulfonates with additional side chains and surface properties, especially the influence of the side chains, were studied. From the surface tension measured in pure water and 0.171 tool·L^-1 NaCl solutions, the following parameters were calculated：the critical micelle concentration （cmc）, the surface excess concentration at surface saturation （Γmax）, the minimum area （Amax）, the surface tension at the cmc （γmax）, the effectiveness of a surfactant in reduing surface tension （πcmc）, the efficiency of a surfactant in reduing surface tension（pC20）, the standard free energy change upon adsorption（△Gad^0）. The main chain and side chain have different effects on the surface properties. With increasing the number of carbons in the main chain or the side chains, cmc decreases, but the decrease degree of cmc is quite different, the main chain decreases cmc to a greater degree than the side chains do. While the number of carbons increases, the main chain increases Γmax, but the side chain decreases Γmax. These surface properties were explained by the structures of sodium alkylbonzensulfonate with additional side chains.