Microstructured templates produced using femtosecond laser pulses as templates for the deposition of mesoporous silicas

A combination of laser-based top-down and chemical bottom-up processes to prepare hierarchical (pore) structures is presented. Polymer templates with dimensions in the micrometer regime are fabricated by two-photon polymerization of an acrylate monomer and are subsequently infiltrated with mesostructured silica using the liquid crystal templating approach. Calcination, which removes both the macro-templating polymer and the nano-templating surfactant molecules, can be carried out so that the morphology of the sample is preserved, delivering SBA-15-type mesoporous constructs which correspond to a replica (or an inverse copy) of the initial polymer structure. This is shown here on simple line structures and on woodpile structures as examples. As the two-photon polymerization allows the controlled construction of various imaginable shapes, mesoporous materials can be constructed with practically any desired morphology on the micrometer scale. The dual pore system of macro- and mesopores classifies these materials as hierarchical pore systems with applications in catalysis and sorption. In addition, the versatility of silica surface chemistry opens new venues for the fabrication of photonic crystals and the general biocompatibility of silica allows the construction of scaffolds for biomedical applications.