Solid-polymer mesoporous membrane

In most polymerizations the kind of dispersed system changes in the course of the process owing the fact that a gaseous or liquid monomer is transformed into a solid polymer. Examples are catalytic gas-phase polymerizations on solid catalyst beads (1) or polymerizations in liquid continuous phases of gaseous monomers. Heterophase polymerization can also be carried out in pores of inorganic solid materials such as Zeolites (2-5), or mesoporous MCM-41 and similar silicates (6,7), or inside interlayers of montmorillonite (8). Other special types of heterophase polymerizations in a solid continuous phase are used to modify the pores in solid polymer monoliths (9) or pores in polymeric membranes (10). 

While most solid-polymer mixed-matrix membranes rely on sieve micropores to generate high selectivities within the membrane by discriminating between gas penetrants, mesoporous molecular sieves have been studied as well. These mesoporous sieves arc used to increase permeabUity in mixed-matrix membranes, instead of enhancing selectivity. Mesoporous MCM-41 incorporated into a polysulfone matrix improved membrane permeability for aU gases tested. The selectivity of pure polysulfone was maintained, as expected. Mesoporous sieves are an excellent material for highly selective polymer membranes that require increased productivity however, nanoscopic-scale crystals will probably be required to enable accommodation within the submicron selective layer typical for high-performance asymmetric membranes in use today. 

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