Hydrophilic gels with new superstructures and their hybrids by nanocasting technologies

摘要

The polymerization of hydrophilic monomers, such as acrylamide, in the nanoscale confinement of lyotropic surfactant phases or microemulsions produces gels with variable pore architecture in the hundreds of nanometers to micrometers size range. The porous gels are characterized by scanning electron microscopy after critical-point drying. The structure of the gels is not a direct copy of the structure and symmetry of the parental surfactant assemblies, but depends on the type of monomer, cross-linking density and both the monomer and surfactant concentration. Nevertheless, a controlled structure set-up is obtained, where different pore morphologies and different pore sizes can be systematically adjusted. In such a way it is possible to build the polymer network structure on a mesoscopic length scale, optimizing different network properties which are otherwise coupled in an opposite fashion, e. g. polymer networks with very large pore size and high mechanical stability can be made. Such porous gels are interesting for modern gel-monolith separation techniques, such as gel electrophoresis for protein and DNA separation where micron sized pores are required. Implementation of a further "nanocasting"-procedure within the pore channel system of these gels allows generation of polymer/inorganic hybrid materials with a similar degree of mesoscale organization and exciting combinations of material properties. The value of such a multiple replica procedure is demonstrated by making superparamagnetic rubbers ("elastic magnets") and highly porous, continuous TiO_2-networks for photocatalytic applications.