Magnetic assisted self-assembly

Materials produced via self-assembly of nano- and micro-particles are becoming of great interest in many applications, such as in chromatography, membrane separation, catalyst supports, bio-inspired materials, and scaffolds for cell growth. These materials can be prepared from colloidal suspensions of polymer or ceramic particles such as silica or alumina, and have usually a random porous structure. One of the biggest challenges is to prepare materials with a better organized pore structure. We have recently introduced a new method, called magnetic gelation, which allows one to create porous polymeric material with anisotropic structure. This method, although effective, is limited to the production of polymeric monoliths where the polymers can be produced via miniemulsion free radical polymerization. In this work we present a different strategy, which allows one to increase the range of materials that can be used for the production of monoliths with organized pore structure. In this process, polymeric-magnetite nanoparticles are not gelled, but are used as directing agents in a sol gel growth of silica. The particles are aligned with an external magnetic field during the silica condensation. After completing the sol gel process the polymer particles are burned out by calcination, leading to an anisotropic silica monolith.