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Helping Strands: Polyelectrolyte Assists in Surfactant Assembly below Critical Micelle Concentration.
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2019-12-18 , DOI: 10.1021/acs.jpcb.9b08692 Brandon K Schabes 1 , Geraldine L Richmond 1
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2019-12-18 , DOI: 10.1021/acs.jpcb.9b08692 Brandon K Schabes 1 , Geraldine L Richmond 1
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Strongly adsorbing polymer/surfactant (P/S) combinations have been proposed for long-term applications such as emulsion stabilization. However, P/S systems are known to exhibit nonequilibrium behavior despite steady-state surface characteristics. This work examines the coadsorption of dodecyltrimethylammonium bromide and sodium poly(styrene sulfonate) (PSS) using oil/water tensiometry, UV absorption, and vibrational sum frequency spectroscopy. To determine which features do not represent true equilibrium, the molecular details of PSS adsorption are compared for fresh and aged samples. At surfactant concentrations concurrent with bulk precipitation, significant differences between fresh and aged samples indicate that the strong initial coadsorption within this system is a nonequilibrium feature. We conclude that the long equilibration timescales arise from the slow assembly of non-adsorbing polyelectrolyte/micelle complexes below the critical micelle concentration. This study resolves a recent debate regarding system equilibria of surface-active P/S combinations at a water surface.
中文翻译：
辅助链：聚电解质有助于胶束浓度低于临界胶束浓度的表面活性剂组装。
已提出将强吸附性聚合物/表面活性剂（P / S）组合用于诸如乳液稳定剂的长期应用。但是，已知P / S系统具有稳态表面特性，但仍表现出非平衡行为。这项工作检查了十二烷基三甲基溴化铵和聚（苯乙烯磺酸钠）（PSS）的油/水张力测定法，紫外线吸收和振动总和光谱的共吸附。为了确定哪些特征不能代表真正的平衡，对新鲜样品和老化样品的PSS吸附分子细节进行了比较。在表面活性剂浓度与大量沉淀同时进行的情况下，新鲜样品与老化样品之间的显着差异表明，该系统中强烈的初始共吸附是非平衡特征。我们得出结论，长的平衡时间尺度是由低于临界胶束浓度的非吸附性聚电解质/胶束复合物的缓慢组装引起的。这项研究解决了关于水表面上表面活性P / S组合的系统平衡的最新争论。
更新日期：2019-12-19
中文翻译：
辅助链：聚电解质有助于胶束浓度低于临界胶束浓度的表面活性剂组装。
已提出将强吸附性聚合物/表面活性剂（P / S）组合用于诸如乳液稳定剂的长期应用。但是，已知P / S系统具有稳态表面特性，但仍表现出非平衡行为。这项工作检查了十二烷基三甲基溴化铵和聚（苯乙烯磺酸钠）（PSS）的油/水张力测定法，紫外线吸收和振动总和光谱的共吸附。为了确定哪些特征不能代表真正的平衡，对新鲜样品和老化样品的PSS吸附分子细节进行了比较。在表面活性剂浓度与大量沉淀同时进行的情况下，新鲜样品与老化样品之间的显着差异表明，该系统中强烈的初始共吸附是非平衡特征。我们得出结论，长的平衡时间尺度是由低于临界胶束浓度的非吸附性聚电解质/胶束复合物的缓慢组装引起的。这项研究解决了关于水表面上表面活性P / S组合的系统平衡的最新争论。
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