顺磁共振和紫外光谱法研究SDS-PEO体系的相互作用

合成更疏水的自旋探针4 羰基 2，2，6，6 四甲基哌啶氮氧自由基 2，4 二硝基苯腙.用顺磁共振（ESR）和紫外光谱法研究了十二烷基硫酸钠（SDS） 0.5 ％(w，质量分数)聚氧乙烯（PEO）体系的分子间相互作用. ESR结果表明,此水溶液体系的微极性随SDS浓度增大而减小，并且SDS与PEO聚集体具有更加紧密的堆积结构使其结合处具有较大的微粘性， SDS与PEO间的相互作用导致PEO分子链伸展. UV表明自旋探针分子可能靠近胶束的表面存在， 2，4 二硝基苯肼基团可能位于靠近SDS的硫酸根基团，定向于SDS胶束的表面，氮氧自由基基团短距离渗透到SDS胶束的碳氢核.

Investigation on the Interaction of Sodium Dodecyl Sulfate with Poly(Ethylene Oxide) by Electron Spin Resonance and UV Spectrum

ESR and UV spectrum of the aqueous solution of sodium dodecyl sulfate(SDS)/poly(ethylene oxide)(PEO) were measured at room temperature respectively, the concentration of PEO was 0.5％ (mass fraction), and the concentration of SDS (mSDS) was up to 50 mmol· kg－ 1. 2,4-dinitrophylhydrazone of 2,2,6,6-tetramethyl-4-piperidine-1-oxyl (Tempone-DNPH) was synthesized and used as ESR probe. The binding site of SDS-PEO interaction, the micropolarity and microviscosity information of the microenvironments have been determined by ESR. UV spectrum gives information on the environment of 2,4-dinitrophylhydrazone group. The hyperfine coupling constant and the rotational correlation time of the spin probe reflect the microenvironment of the polymer-micelle aggregates. The micropolarity of the solutions decreases with increasing SDS concentration, the polymer-micelle aggregate forms a more compact structure at the binding site and the binding site between PEO and SDS micelles yields a strong increase of the microviscosity at the micelle-polymer interface. Spin probe is located near the surface of the micelle. 2,4-dinitrophylhydrazone group may be adjacent to the sulphate groups, and the nitroxide group penetrates a small distance into the hydrocarbon core of the micelle. The critical aggregation concentration (CAC)and polymer saturation point (PSP) of SDS-0.5 ％ PEO at room temperature are approximately 4 and 28 mmol· kg－ 1, respectively.