Surface dilational viscoelasticity of aqueous surfactant solutions by surface quasi-elastic light scattering
Surface dilational viscoelasticity of aqueous surfactant solutions by surface quasi-elastic light scattering
复制标题
通过表面准弹性光散射研究表面活性剂水溶液的表面膨胀粘弹性
DOI：
10.1007/s00396-018-4297-8
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发表时间：
2018
影响因子：
2.4
通讯作者：
M. Aratono
中科院分区：
文献类型：
--
作者：
S. Ueno;Y. Takajo;S. Ikeda;R. Takemoto;Y. Imai;T. Takiue;H. Matsubara;M. Aratono
研究了二己酰磷脂酰胆碱（DC 6PC）、二辛酰磷脂酰胆碱（DC 8 PC）、十二烷基三甲基溴化铵（DTABr）、十二烷基三甲基溴化铵与溴化钠（NaBr）、十二烷基三甲基四氟硼酸铵（DTABF 4）、双十二烷基三甲基硫酸铵（DTA 2SO 4）以及含氧杂环的非离子表面活性剂（C10 E5）水溶液的表面扩张粘弹性。我们测量了表面准弹性光散射（SQELS）光谱，并通过表面流变学和唯象拟合方法分析了溶液。对于DC 6PC-DC 8 PC混合物，还应用了电毛细管波（ECW）方法。吸附膜中DC 8 PC和DC 6PC之间的分子相互作用明显影响了几毫秒（ECW）量级的弛豫过程。然而，这种影响在几百微秒（SQELS）的量级上影响较小。由于交错结构的形成，弛豫的特征频率可能发生在150至300 Hz的范围内。在250-400 kHz的DTABr的扩张弹性表明，影响扩张性能的主要弛豫过程既不是表面活性剂从体相到次表面的扩散，也不是表面活性剂离子在吸附层和次表面之间的吸附-脱附。然而，斯特恩和扩散层之间的抗衡离子的扩散发生在几微秒的时间尺度上。对C10 E5的研究表明，SQELS研究捕获的弛豫过程既与表面活性剂扩散也与表面活性剂重取向无关，而可能是一个弛豫过程，其中水化球的变形和/或水化球的水化-脱水是由水分子的扩散引起的。
We investigated the surface dilational viscoelasticities of aqueous solutions of dihexanoyl-phosphastidylcholine (DC6PC) and dioctanoyl-phosphastidylcholine (DC8PC), dodecyltrimethylammonium bromide (DTABr) and DTABr and sodium bromide (NaBr), dodecyltrimethylammonium tetrafluoroborate (DTABF4) and bisdodecyltrimethylammonium sulfate (DTA2SO4), and nonionic surfactants with oxyethylene units (C10E5). We measured surface quasi-elastic light scattering (SQELS) spectra and analyzed the solutions by both surface rheological and phenomenological fitting approaches. For the DC6PC-DC8PC mixture, the electrocapillary wave (ECW) method was also applied. The molecular interactions between DC8PC and DC6PC in the adsorbed film clearly influenced the relaxation process on the order of several milliseconds (ECW). However, the effects were less influential on the order of several hundreds of microseconds (SQELS). The characteristic frequencies for relaxation owing to the staggered structure formation likely occurred in the range from 150 to 300 Hz. The dilational elasticity at 250–400 kHz of DTABr suggested that the main relaxation process influencing the dilational properties was neither diffusion of surfactants from the bulk phase to the subsurface nor an adsorption-desorption of surfactant ions between the adsorbed layer and subsurface. However, the diffusion of counterions between the Stern and diffuse layers occurred on a time scale of several microseconds. Studies of C10E5suggested that the relaxation process captured by the SQELS studies was neither related to surfactant diffusion nor surfactant reorientation, but rather was likely to be a relaxation process where distortion of the hydration sphere and/or hydration-dehydration to/from the hydration sphere was caused by diffusion of water molecules.