McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
Soft Matter. 2017 Feb 15;13(7):1335-1343. doi: 10.1039/c6sm02718k.
Porous mesophases, where well-defined particle-depleted 'void' spaces are present within a particle-rich background fluid, can be self-assembled from colloidal particles interacting via isotropic pair interactions with competing attractions and repulsions. While such structures could be of wide interest for technological applications (e.g., filtration, catalysis, absorption, etc.), relatively few studies have investigated the interactions that lead to these morphologies and how they compare to those that produce other micro-phase-separated structures, such as clusters. In this work, we use inverse methods of statistical mechanics to design model isotropic pair potentials that form porous mesophases. We characterize the resulting porous structures, correlating features of the pair potential with the targeted pore size and the particle packing fraction. The former is primarily encoded by the amplitude and range of the repulsive barrier of the designed pair potential and the latter by the attractive well depth. We observe a trade-off with respect to the packing fraction of the targeted morphology: greater values support more spherical and monodisperse pores that themselves organize into periodic structures, while lower values yield more mobile pores that do not assemble into ordered structures but remain stable over a larger range of packing fraction. We conclude by commenting on the limitations of targeting a specific pore diameter within the present inverse design approach as well as by describing future directions to overcome these limitations.
多孔介相是指在富含粒子的背景流体中存在着明确的粒子耗尽的“空洞”空间，可以通过各向同性的粒子间相互作用自组装而成，这种相互作用同时存在着竞争的吸引力和排斥力。虽然这种结构可能在技术应用中有广泛的兴趣（例如过滤、催化、吸收等），但相对较少的研究关注导致这些形态的相互作用，以及它们与其他微相分离结构（例如簇）相比的情况。在这项工作中，我们使用统计力学的逆方法来设计形成多孔介相的模型各向同性对势。我们对得到的多孔结构进行了特征化，将对势的特征与目标孔径和粒子堆积分数联系起来。前者主要由设计对势的排斥势垒的幅度和范围编码，后者由吸引力阱的深度编码。我们观察到针对目标形态的堆积分数存在一种权衡：更大的值支持更球形和单分散的孔，这些孔本身组织成周期性结构，而更小的值产生更易移动的孔，这些孔不会组装成有序结构，但在更大的堆积分数范围内保持稳定。最后，我们通过描述克服这些限制的未来方向，评论了在目前的逆设计方法中针对特定孔径的限制。
