An In Situ Approach to Create Porous Ceramic Membrane: Polymerization of Acrylamide in a Confined Environment

A new processing method for the fabrication of porous ceramic membrane has been developed via a three-step procedure: by uniformly distributing a solid vinyl monomer (e.g., acrylamide) into a green object of ceramic through wet chemistry mixing and compression molding; polymerizing the monomer in a highly compact surrounding, leading to the formation of embedded chain assemblies of polyacrylamide; and removing the polymer via carbonization and calcination. This in situ pore-forming strategy grants less tortuous and well-interconnected pore channels in contrast to the approach of using polymeric porogen such as starch or cellulose. The weight% of initiator and duration of polymerization were scrutinized using thermal analysis, electron microscopy, and Hg porosimetry to understand their influences on the porous structure of sintered ceramic membrane, e.g., a thin Yttria-stabilized zirconia disc, and ultimately its gas permeability. The advantage of this pore-forming method lies in the fact that the monomer can be homogenously distributed in the green object in a confined space and the polymer chains formed during the in situ solid state polymerization can develop space occupancy through chain penetration and association, thus leaving behind interconnecting pore channels and more open pores after they were removed eventually. In this study, it has been shown that the resulting porous ceramics manifests a marked improvement (20-80%) in gas permeability over those fabricated by using starch as the pore-former. Furthermore, the porous ceramics fabricated by the new method exhibited higher rapture resistivity on the similar porosity basis.