Dipartimento di Fisica, Università di Milano, Via Celoria 16, 20133 Milano, Italy.
Soft Matter. 2017 Dec 13;13(48):9259-9272. doi: 10.1039/c7sm02125a.
Colloidal fluids interacting via effective potentials which are attractive at the short range and repulsive at the long range have long been raising considerable attention because such an instance provides a simple mechanism leading to pattern formation even for isotropic interactions. If the competition between attraction and repulsion is strong enough, the gas-liquid phase transition is suppressed, and replaced by the formation of mesophases, i.e., inhomogeneous phases displaying periodic density modulations whose length, although being larger than the particle size, cannot nevertheless be considered macroscopic. We describe a fully numerical implementation of density-functional theory in three dimensions, tailored to periodic phases. The results for the equilibrium phase diagram of the model are compared with those already obtained in previous investigations for the present system as well as for other systems which form mesophases. The phase diagram which we find shows a strong similarity with that of block copolymer melts, in which self-assembly also results from frustration of a macroscopic phase separation. As the inhomogeneous region is swept by increasing the density from the low-density side, one encounters clusters, bars, lamellae, inverted bars, and inverted clusters. Moreover, a bicontinuous gyroid phase consisting of two intertwined percolating networks is predicted in a narrow domain between the bar and lamellar phases.
胶体流体通过有效势能相互作用，在短程上具有吸引力，在长程上具有排斥力，长期以来一直引起相当大的关注，因为这种情况提供了一种简单的机制，即使对于各向同性相互作用，也能导致图案形成。如果吸引力和排斥力之间的竞争足够强，气体-液体的相变就会被抑制，取而代之的是介相的形成，即不均匀的相，显示出周期性的密度调制，其长度虽然大于颗粒尺寸，但不能被认为是宏观的。我们描述了一种针对周期性相的三维密度泛函理论的完全数值实现。我们将模型的平衡相图的结果与之前对该系统以及其他形成介相的系统的研究结果进行了比较。我们发现的相图与嵌段共聚物熔体的相图非常相似，在嵌段共聚物熔体中，自组装也是由宏观相分离的受挫引起的。随着密度从低密度侧增加，不均匀区域被扫过，会遇到团簇、棒状、层状、倒棒状和倒团簇。此外，在棒状和层状相之间的狭窄区域内，预测会出现由两个交织的渗透网络组成的双连续胞状相。
