Chemical phase separation strategies towards silica monoliths with hierarchical porosity.

In this tutorial review the preparation of monolithic silica materials with hierarchical porosity by the competing processes of sol-gel transition and chemical phase separation is summarized. Four principally different routes will be discussed in detail, including multiple micellar as well as high internal phase emulsion templating routes. Special emphasis is given to polymer-induced phase separation strategies either based on the deliberate choice of the polymer that is mixed into the gelling system or by the application of specifically designed hydrophilic silane precursors.