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

Abstract

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.

Evolution of throttle-channel dual pores in YSZ ceramic monolith through in situ grown nano carbon wedges

“…The MOR for a rectangular test specimen can be calculated using the standard approach. 15 An average of 7 readings was obtained for a sample produced using the same set of conditions.…”

“…The pore size distribution and porosity of the sintered discs were measured by mercury porosimetry (Micrometrics AutoPore III, Norcross, GA, US). The air permeability of a sintered YSZ disc was measured using the module designed in our previous study 15,16 and the Darcy's permeability of the porous ceramic was calculated. Similarly, the edge of the pellet was sealed with aluminum sticker to prevent any leakage of air.…”

“…A novel processing technique involving in situ polymerization of vinyl or aromatic amide monomers in the green body has been studied to circumvent this mixing restriction. 15 The fundamental idea revolves around the usage of monomers instead of polymers as the starting material for the role of pore-former. The much smaller sized monomers, compared to their polymerization products, can be readily "dissolved" in the ceramic green body.…”

Designing nanoporosity in a swollen polymer for the controlled release of a highly volatile fragrance

“…The nanoporosity of the polymer arises from the swelling of the polymer when the fragrance interacts with the polymer chain. Therefore, traditional methods using gas (particularly, nitrogen) adsorption, mercury intrusion, or microscopic imaging cannot be applied because of the small pore range (<1 nm) of the PUA matrix before swelling. Moreover, these techniques cannot be applied to the swollen polymer matrix.…”

Aramid‐Al2O3 Nano‐Needle Scaffold as Pore Former for Optimal Mechanical and Permeable Properties of Ceramic Matrix

“…, the mechanistic aspect of this in‐situ grafting polymerization of PPTA oligomer chains with Sasol needles shows achieving a scaffold that blocks the stacking of PPTA chains. In this work, YSZ ceramic was adopted to demonstrate this pore‐forming strategy on the basis of our previous studies . An important consideration comes from the implementation of excess –NH 2 end groups versus the –COOH end groups attempting to shorten the molecular weight of the resultant PPTA molecules.…”