Preparation of mesoporous silica monoliths with ordered arrays of macrochannels templated from electric-field-oriented hydrogels.

The fabrication of ordered inorganic arrays of varying length scales and with multimodal porosities is of practical importance owing to their potential application in many areas of materials chemistry, including catalysis and separations science. A common approach to the controlled synthesis of this class of materials, first exploited in the synthesis of the MCM-41 family of molecular sieves, is to polymerize the inorganic phase around an organic template by using a sol–gel process. The organic phase is then removed by calcination leaving a void space that is a replica of the size, orientation, and arrangement in space of the template. By using multiple templates of different length scales, hierarchically porous inorganic structures containing various combinations of micro-, meso-, and macropores have been realized. We report herein the creation of a mesoporous silica monolith that contains oriented macroporous channels, which is achieved by the application of an electric field to a hydrogel template during polymerization and cross-linking. 9] To the best of our knowledge, this is first time an external electric field has been used to create ordered, hierarchical meso-/ macroporous silicate materials. The template matrix is created through the electrical alignment of a polyacrylamide hydrogel, which is accomplished by copolymerizing a mixture of acrylamide functionalized with immobiline and bisacrylamide in the presence of an electric field (60 Vcm ). The presence of this field creates interstitial voids of approximately 10 mm in diameter. The channel structure, which can be imaged through confocal microscopy, is present in the field-oriented hydrogel (Figure 1a), but is replaced by a disordered structure (Figure 1b) when no field is applied.