Perspective on the influence of interactions between hard and soft templates and precursors on morphology of hierarchically structured porous materials

When surfactant templates and hard templates are combined to synthesize silica and other inorganic solids with hierarchical pore structure, the mesopore development and orientation are influenced by interactions between the surfactant templates and the hard templates. Effects such as confinement, surface interactions, and curvature can be used to control the relative mesopore alignment. Such control is important for numerous applications that rely on access to the mesopores and incorporation of multiple components in a hierarchical structure. This review highlights how the interactions between molecular and block-copolymer surfactant micelles and confining surfaces can be used to influence mesopore architecture. After a brief review of block-copolymer systems, more complex systems will be considered that combine block-copolymers and inorganic precursors on a single surface, between two planar surfaces, confined in channels of porous anodic alumina membranes, in colloidal crystal templates, and in three-dimensionally ordered macroporous solids. The influence of confinement on external product morphology and on the distribution of multiple phases in porous materials with complex composition will also be described briefly. The review will conclude with a perspective on developments needed to facilitate further progress and new applications in this field of research.