In a previous publication (Xie et al., Langmuir 29, 2659 (2013)), we demonstrated that polymer solutions, which display a bulk lower critical solution temperature (LCST) may undergo a phase transition in a porous environment below the LCST. Such capillary induced transitions are thus supra-critical, given that the associated bulk solution only contains a single fluid phase. The current work explores this phenomenon for mixtures of simple particles, with ostensibly isotropic interactions, that also display a bulk LCST. We demonstrate that capillary-induced phase transitions may occur at temperatures considerably below the LCST, in these cases as well. The connection to systems with anisotropic interactions, e.g., aqueous solutions containing hydrogen-bonding solutes, is also elucidated. In contrast to the complex analysis carried out in polymeric systems, a simple classical density functional approach is employed here, which serves to illustrate the ubiquitous nature of this phenomenon. This makes the conclusions of the present study more accessible to researchers in a range of fields, which may inspire experimental confirmation of our qualitative theoretical predictions. Possible future applications may include utilisation of this phenomenon in chromatographic methods.

在先前的出版物（解等人，Langmuir 29，2659（2013）），我们表明，聚合物溶液，其显示一个散装低临界溶解温度（LCST）是一个多孔环境可经历相变，下面的LCST。因此，这种毛细管诱导的转变是超临界的，因为相关的本体解决方案仅包含单个流体相。当前的工作探讨了表面上各向同性相互作用的简单颗粒混合物的现象，这种现象也显示出大量的LCST。我们证明，在这些情况下，毛细管诱导的相变也可能在低于LCST的温度下发生。还阐明了与具有各向异性相互作用的系统的连接，例如含有氢键溶质的水溶液。与在聚合物系统中进行的复杂分析相反，此处采用了一种简单的经典密度泛函方法，该方法可用来说明这种现象的普遍性。这使得各个领域的研究人员都更容易获得本研究的结论，这可能会激发我们对定性理论预测的实验证实。未来可能的应用可能包括在色谱方法中利用这种现象。