非电解质聚合物与烷基硫酸钠同系物间团簇化临界浓度的变化规律

CRITICAL CONCENTRATION OF SURFACTANT IN CLUSTERIZATION OF ROSO_3Na HOMOLOGS ON NONELECTROLYTIC MACROMOLECULES

用表面张力 (γ)法研究了非电解质聚合物聚乙烯吡咯烷酮 (PVP)或聚乙二醇 (PEG)与烷基硫酸纳同系物中十四烷基硫酸钠 (SMS)、十二烷基硫酸钠 (SDS)及十烷基硫酸钠 (SDeS)间团簇化临界浓度的变化规律 .上述软物质团簇的γ lgc曲线均具有双拐点即拟双平台特征 ,表明在双拐点之间非电解质聚合物与烷基硫酸钠形成软物质团簇 .对应于双拐点有两个表面活性剂临界浓度值c1 和c2 ,且符合c1 <cmc<c2 的基本规律 .实验结果表明 ,同系聚合物的分子量变化及浓度变化对指定链长的烷基硫酸钠的c1 值影响不显著 ,c1 基本为一不变量 ;而当烷基硫酸钠的疏水基增长时 ,lgc1 随疏水基碳原子数 (n)的增加呈线性单调减小 .c1 与n之间满足下列关系 :对PVP RSO4 Na团簇化体系lgc1 =1 5 8- 0 341n(R2 =0 9981) ,对PEG RSO4 Na团簇化体系lgc1 =1 38- 0 313n(R2 =0 9993) .实验结果还表明 ,在聚合物质量浓度 (或链节浓度 )相同的前提下 ,聚合物分子量变化对c2 值亦基本无影响 .

The critical concentration of surfactant in clusterization of sodium tetradecyl sulfate SMS), sodium dodecyl sulfate (SDS) and sodium decyl sulfate (SDeS) on polyvinylpyrrolidone (PVP homolog or polyetheleneglycol (PEG) homolog was studied by means of surface tension. There occur bis-transition points or pseudo double-plateau regions in the gamma-lgc curves of the above clusterization systems, which means that soft matter clusters are yielded between the two critical concentrations. The two critical concentration values c(1) and c(2) could be found along with these gamma-lgc curves, and they fulfil the relationship of c(1) < cmc < c(2). The c(1) value of a given surfactant is basically an invariant, which is independent on the molecular weight and concentration of a certain homolog of macromolecule. Moreover the value of c(1) is decreased with the increase of hydrophobicity of the surfactant homolog. The relation between lg c(1) and n, the number of alkyl chain carbons of a surfactant, is simply decreasing, which can be expressed by linear equations: lg c(1) = 1.58 - 0.341 n (R-2 = 0.9981)for PVP-ROSO, Na soft clusters and lg c(1) = 1.38 - 0.313n (R-2 = 0.9993) for PEG-ROSO3Na soft clusters. Meanwhile the value of c(2) is independent on the molecular weight of the polymer under the same polymer concentrations.