arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.07152cond-mat.soft
收藏

含胶束和胶体颗粒的表面活性剂浓溶液液膜中的涡旋

Vortex in liquid films from concentrated surfactant solutions containing micelles and colloidal particles

E. S. Basheva, P. A. Kralchevsky, K. D. Danov, R. D. Stanimirova, N. Shaw, J. T. Petkov

摘要:

假设:在从双峰粒径分布的胶体溶液中蒸发自由液膜的过程中,可以观察到新的动力学现象。这样的分布是以自然的方式形成的混合溶液(轻微浑浊)的阳离子和阴离子表面活性剂,其中纳米级胶束与微米级沉淀颗粒共存。实验:在不蒸发水的情况下,薄膜变薄至厚度< 100 nm。当水从膜蒸发时,观察到自发的膜增厚(高于300 nm)和在中心具有较薄膜的斑点的动态涡旋的出现。涡旋壁具有阶梯状轮廓,阶梯高度等于有效胶束直径(约100 μ m)。8 nm)和多达20-30个分层步骤。结果:对于大于100 nm的厚度,从胶束溶液中的泡沫膜分层从未观察到。这证明在蒸发膜中形成了厚的胶束胶体晶体。较大的微米级颗粒的作用是在高原边界形成滤饼,其支撑厚膜。定量力学模型表明,阶梯状涡廓线是由流体动力学和表面张力力的平衡所稳定的。涡旋不仅在阴阳离子表面活性剂溶液的膜中观察到,而且在二氧化硅和胶乳颗粒悬浮液的膜中也观察到,其中含有较小的表面活性剂胶束。

英文摘要:

Hypothesis: New dynamic phenomena can be observed in evaporating free liquid films from colloidal solutions with bimodal particle size distribution. Such distributions are formed in a natural way in mixed (slightly turbid) solutions of cationic and anionic surfactants, where nanosized micelles coexist with micronsized precipitated particles. Experiment: Without evaporation of water, the films thin down to thickness < 100 nm. Upon water evaporation from the film, one observes spontaneous film thickening (above 300 nm) and appearance of a dynamic vortex with a spot of thinner film in the center. The vortex wall has a stepwise profile with step-height equal to the effective micelle diameter (ca. 8 nm) and up to 20-30 stratification steps. Results: For thicknesses greater than 100 nm, stratification in foam films from micellar solutions has never been observed so far. It evidences for the formation of a thick colloidal crystal of micelles in the evaporating film. The role of the bigger, micronsized particles is to form a filtration cake in the Plateau border, which supports the thick film. The developed quantitative mechanical model shows that the stepwise vortex profile is stabilized by the balance of hydrodynamic and surface tension forces. Vortex is observed not only in films from catanionic surfactant solutions, but also in films from silica and latex particle suspensions, which contain smaller surfactant micelles.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑