EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom.
Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom.
J Phys Chem B. 2020 Jul 16;124(28):6004-6014. doi: 10.1021/acs.jpcb.0c03876. Epub 2020 Jul 7.
Deep eutectic solvents (DES) are potentially greener solvents obtained through the complexation of simple precursors which, among other applications, have been investigated in recent years for their ability to support the self-assembly of amphiphilic molecules. It is crucial to understand the factors which influence surfactant solubility and self-assembly with respect to the interaction of the surfactant molecule with the DES components. In this work, small-angle neutron scattering (SANS) has been used to investigate the micellization of cationic (CTAB) and anionic (SDS) surfactants in a ternary DES comprising choline chloride, urea, and glycerol, where the hydrogen bond donors are mixed in varying molar ratios. The results show that in each case either globular or rodlike micelles are formed with the degree of elongation being directly dependent on the composition of the DES. It is hypothesized that this composition dependence arises largely from the poor solubility of the counterions in the DES, especially at low glycerol content, leading to a tighter binding of the counterion to the micelle surface and giving rise to micelles with a high aspect ratio. This potential for accurate control over micelle morphology presents unique opportunities for rheology control or to develop templated syntheses of porous materials in DES, utilizing the solvent composition to tailor micelle shape and size, and hence the pore structure of the resulting material.
深共熔溶剂（DES）是通过简单前体的络合获得的潜在更环保的溶剂，近年来，它们在支持两亲分子自组装的能力方面的应用受到了广泛关注。了解影响表面活性剂溶解度和自组装的因素对于理解表面活性剂分子与 DES 组分的相互作用至关重要。在这项工作中，使用小角中子散射（SANS）研究了阳离子（CTAB）和阴离子（SDS）表面活性剂在包含氯化胆碱、尿素和甘油的三元 DES 中的胶束化，其中氢键供体以不同的摩尔比混合。结果表明，在每种情况下，要么形成球形胶束，要么形成棒状胶束，其伸长程度直接取决于 DES 的组成。据推测，这种组成依赖性主要源于 DES 中抗衡离子的溶解度差，尤其是在甘油含量低的情况下，导致抗衡离子与胶束表面的结合更紧密，从而形成具有高纵横比的胶束。这种对胶束形态进行精确控制的潜力为流变学控制或在 DES 中开发模板合成多孔材料提供了独特的机会，利用溶剂组成来调整胶束的形状和大小，从而调整所得材料的孔结构。
