Method for preparing vinyl terminated fluorine-containing polydiorganosiloxane

Claim 1

A method for preparing a liquid polydiorganosiloxane of the average molecular formula ViR" 2 Si(OSiRR') n OSiR" 2 Vi where each R is individually a monovalent saturated or aromatic hydrocarbon radical containing from 1 to 20 carbon atoms, from 50 to 100% of the R' radicals represent the radical RfCH 2 CH 2 -- where Rf in turn represents a perfluoroalkyl radical containing from 1 to 10 carbon atoms, any remaining R' radicals being selected from the same group as R, R" is selected from the same group as R or R', Vi represents a vinyl radical, and n represents an integer from 10 to 200 and is equivalent to a viscosity value for said polydiorganosiloxane of from 0.2×10 -3 to about 0.01 m 2 /second at 25° C., said method comprising the steps of (1) reacting a cyclotrisiloxane of the general formula (SiORR') 3 with from 1.5 to about 50 mole percent, based on said cyclotrisiloxane, of water at a temperature of from 25° to 150° C. in a closed vessel and in the presence of an amount of ammonia sufficient to generate a pressure of from 140 to 1050 kilopascals within said vessel and continuing the reaction for a time period sufficient to form a silanol terminated polymer represented by the average formula HO(RR'SiO) n H, (2) reacting each mole of said hydroxyl terminated polymer with at least one mole of a disilazane of the formula (ViR" 2 Si) 2 NH, at a temperature of from 50 to 100° C. for a sufficient time to form said polydiorganosiloxane, and (3) isolating said polydiorganosiloxane from the reaction mixture.

Claim 2

A method for preparing a liquid polydiorganosiloxane of the average molecular formula ViR" 2 Si(OSiRR') n OSiR" 2 Vi where each R is individually a monovalent saturated or aromatic hydrocarbon radical containing from 1 to 20 carbon atoms, from 50 to 100% of the R' radicals represent the radical RfCH 2 CH 2 -- where Rf in turn represents a perfluoroalkyl radical containing from 1 to 10 carbon atoms, any remaining R' radicals being selected from the same group as R, R" is selected from the same group as R or R', Vi represents a vinyl radical, and n represents an integer from 10 to 200 and is equivalent to a viscosity value for said polydiorganosiloxane of from 0.2×10 -3 to about 0.01 m 2 /second at 25° C., said method comprising the steps of (1) reacting a cyclotrisiloxane of the general formula (SiORR') 3 with from 1.5 to about 50 mole percent, based on said cyclotrisiloxane, of water at a temperature of from 25° to 150° C. in a closed vessel and in the presence of an amount of ammonia sufficient to generate a pressure of from 140 to 1050 kilopascals within said vessel and continuing the reaction for a time period sufficient to form a silanol terminated polymer represented by the average formula HO(RR'SiO) n H, (2) reacting each mole of said hydroxyl terminated polymer with at least one mole of a disilazane of the formula (ViR" 2 Si) 2 NH, at a temperature of from 50 to 100° C. for a sufficient time to form said polydiorganosiloxane, and (3) isolating said polydiorganosiloxane from the reaction mixture.