Templated Mesoporous Silica Colloids with Controlled Internal Structures

Abstract

Mesoporous silica colloids (MSCs) are synthesized in the cavities of a polymer-based inverse opal. The spherical cavities of the polymer inverse opal provide a highly defined complex three-dimensionally confining environment for the cooperative assembly of silica precursors and the associated triblock copolymer mesophase, which appears to be maintained in the final MSCs. The internal mesostructure of the MSCs is regulated by the diameter, surface chemistry, and connectivity of the cavities in the polymer inverse opal. The diameter of the MSCs is controlled by the diameter of the cavities in the polymer inverse opal. When formed in hydrophilic polymer inverse opals, simple MSCs exhibiting a circularly wound concentric mesostructure are formed. At intermediate surface energies, the mesostructure exhibits a pseudo-rhombohedral dodecahedral organization, and when the MSCs are formed in a hydrophobic polymer inverse opal, their mesostructure becomes disordered. The average number of interconnects between cavities of the polymer inverse opal could be modulated by intentionally ordering or disordering the silica colloidal crystal used to template the polymer inverse opal; increasing disorder decreased the average number of interconnects between cavities. With use of such templates, the effect of interconnects on the MSCs was determined.