Organopolysiloxanes including silicon-bonded trialkylsilyl-substituted organic groups

A hydro silylation-curable silicone composition comprising:

• (A) an organohydrogenpolysiloxane comprising siloxane units, wherein about 5 to about 99.99 mol % of the siloxane units are bound to at least one trialkylsilyl-substituted organic group and about 0.01 to about 30 mol % of the siloxane units are bound to at least one hydrogen atom, wherein the organohydrogenpolysiloxane has a number-average molecular weight of about 2,000 to about 100,000 g/mol;
• (B) a compound having an average of at least two aliphatic unsaturated carbon-carbon bonds per molecule selected from
• (i) at least one organo silicon compound having an average of at least two aliphatic unsaturated carbon-carbon bonds per molecule,
• (ii) at least one organic compound having at an average of at least two aliphatic unsaturated carbon-carbon bonds per molecule, and
• (iii) mixtures comprising (i) and (ii);
• and
• (C) a hydrosilylation catalyst;
• wherein the ratio of the moles of silicon-bonded hydrogen atoms in Component (A) to the sum of the number of moles of aliphatic unsaturated carbon-carbon bonds in the composition is about 0.1 to about 20.

A method of separating gas components in a feed gas mixture, the method comprising:

• contacting a first side of a membrane comprising a cured product of a hydrosilylation-curable silicone composition with a feed gas mixture comprising at least a first gas component and a second gas component to produce a permeate gas mixture on a second side of the membrane and a retentate gas mixture on the first side of the membrane,
• wherein the permeate gas mixture is enriched in the first gas component and the retentate gas mixture is depleted in the first gas component,
• wherein the hydro silylation-curable silicone composition comprises
• (A) an organohydrogenpolysiloxane comprising siloxane units, wherein about 20 to about 99.99 mol % of the siloxane units are bound to at least one trialkylsilyl substituted organic group and about 0.01 to about 30 mol % of the siloxane units are bound to at least one silicon-bonded hydrogen atom, wherein the organohydrogenpolysiloxane has a number-average molecular weight of about 3,500 to about 100,000 g/mol;
• (B) a compound having an average of at least two aliphatic unsaturated carbon-carbon bonds per molecule selected from
• (i) at least one organo silicon compound having an average of at least two aliphatic unsaturated carbon-carbon bonds per molecule,
• (ii) at least one organic compound having at an average of at least two aliphatic unsaturated carbon-carbon bonds per molecule, and
• (iii) mixtures comprising (i) and (ii);
• and
• (C) a hydrosilylation catalyst;
• wherein the ratio of the moles of silicon-bonded hydrogen atoms in Component (A) to the sum of the number of moles of aliphatic unsaturated carbon-carbon bonds in the composition is about 0.1 to about 20, and the membrane has a water vapor permeability of about 5,000 to about 100,000 Barrer at about 22° C.