In this work, we introduce a new technique to produce anisotropic porous materials called magnetic assisted self-assembly. This method takes advantage of the alignment in the presence of a magnetic field of non-magnetic colloidal nanoparticles, either polymeric or ceramic (e.g. silica, alumina), dispersed in an aqueous highly stable ferrofluid. Once the magnetic field is applied, the non-magnetic nanoparticles act as magnetic holes, i.e., they acquire a magnetic moment in the opposite direction to that of the external field. These moments generate dipolar interactions capable of aligning non-magnetic particles in the direction of the applied field. This process is then combined with either colloidal gelation, leading to percolation of the nanocolloids, or with sol-gel chemistry to produce a monolith from a precursor solution, again either polymeric or ceramic, through addition of a catalyst. In this way, the colloidal nanoparticles either act as building blocks for the monolith or as templates on which sol-gel chemistry is used to create a monolith around them.
Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2011: Advanced Materials, CNTs, Particles, Films and Composites
Published: June 13, 2011
Pages: 519 - 522
Industry sector: Advanced Materials & Manufacturing
Topicss: Advanced Materials for Engineering Applications, Composite Materials