反应详情

A 120×120 mm asbestos paper of the 0.025" L/FX36" type manufactured by John Mansville Co. was soaked with a mixture having the following molar composition: 66% of styrene (ST), 34% of divinylbenzene (DVB) and 1% (molar with respect to the total moles of monomers) of dibenzoylperoxide. The paper was then placed in a Teflon-lined press and held at 80° C. for 1 hour at a pressure of 0.5 kg/cm2 to produce a fluid-impervious sheet with a ST/DVB polymer load of 65% by weight. One side thereof was then coated with a mixture of the following composition by moles: 85% of 4-vinylpyridine (4 VP), 15% of divinylbenzene (DVB) and 1% (molar ratio with respect to the total moles of monomers) of dibenzoylperoxide and was then held for 2.5 hours at 80° C. in a reactor to effect copolymerization to obtain a 0.03 mm-thick 4-VP/DVB polymer layer. A double-layer membrane was thus obtained which, after swelling for 10 hours in sym-dichloroethane at 70° C., was then sulfonated at -30° C. with liquid SO3 dissolved in liquid SO2 while raising the temperature to -10° C. over 20 minutes to obtain a sulfonated membrane exhibiting a different polarity on each side. Samples were taken from both sides of the membrane and the elemental analysis thereof gave the following results: