顺磁共振和紫外光谱法研究SDS-PEO体系的相互作用

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

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 .

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 (m(SDS)) was up to 50 mmol . kg(-1). 2, 4-dinitrophylhydrazone of 2, 2, 6, 6-tetramethyl-4- piperidine-1-oxyl (Tempone-DMPH) 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.