Composite membrane of a hydrophilic asymmetric membrane coated with an organosiloxane block copolymer

Abstract

An organosiloxane block copolymer having the formula depicted (I) depicted below: ##STR1## wherein: m has a value of 8.0-18.0; n has a value of 1.0-5.0; x has a value of about 0.2 to about 0.7; y has a value of 1 minus the value of x; R is ##STR2## R.sup.1 ##STR3## R.sup.2 is a C.sub.1 -C.sub.5 lower alkylene group; V is a vinyl group; and Me is a methyl group. Preparation of the organosiloxane block copolymer of the above formula (I) by polymerizing .alpha.,w-bis(oxymethyl)polydimethyl-methylvinylsiloxane, and diphenylmethanediisocyanate, and di(oxyethyl)m-toluidine in the presence of a solvent and a catalyst. A composite membrane, which may be used in a pervaporation process, comprising a hydrophilic asymmetric membrane coated with a mixture of an organosiloxane block copolymer, a linking reagent and a catalytically effective amount of a hydrosilylation catalyst.

Dependencies are inferred from the claim text.