NOVEL FUNCTIONAL POLYMERS - POLY(DIMETHYLSILOXANE)-POLYAMIDE MULTIBLOCK COPOLYMER .7. OXYGEN PERMEABILITY OF ARAMID-SILICONE MEMBRANES IN AGAS-MEMBRANE-LIQUID SYSTEM

Poly(dimethylsiloxane) (PDMS) and aromatic polyamide (aramid) multiblo ck copolymer (PAS) membranes containing greater than or equal to 55 wt % of PDMS were prepared. Their tensile strength, morphology, and oxyg en permeation property were investigated. The observed high tensile st rength of PAS with 55 wt % of PDMS indicates the presence of PDMS-aram id co-continuous phases with lamellar structures; furthermore, the mic rophase-separated structures of PAS membranes were observed by means o f transmission electron microscopy. The overall oxygen permeation resi stance of a conventional silicone rubber showed typical dependence on stirrer speed, which was derived from the macroscopic relationship bet ween the membrane-liquid interfacial resistance and the stirrer speed. However, the overall oxygen permeation resistances of the PAS membran es were found not to simply depend on stirrer speed. Combining with th e oxygen permeability of PAS in the case of a gas-membrane-gas system, the interface resistances of the membranes were evaluated. The interf ace resistances of the PAS membranes with the two-phase nature were mo re susceptible to the hydrodynamic parameter than that of the silicone rubber and became lower than that of the silicone rubber at higher st irrer speeds. The low interface resistance together with the high tens ile strength of the PAS membranes enables us to provide highly oxygen permeable membranes in practical applications with a membrane-liquid i nterface. (C) 1997 John Wiley & Sons, Inc.