A composition which is curable to an elastomer comprising:A polymer or mixture of polymers of the formula ##STR1## wherein: X are monovalent moieties having ethylenic unsaturation which can be the same or different;Y are divalent linking groups which can be the same or different;m is an integer of 0 to 1;D are monovalent moieties which can be the same or different selected from the group consisting of hydrogen, an alkyl group of 1 to about 10 carbon atoms, aryl, and substituted aryl;R are divalent hydrocarbon groups which can be the same or different;R.sup.1 are monovalent moieties which can be the same or different selected from the group consisting of alkyl, substituted alkyl, aryl, and substituted aryl;R.sup.2 are monovalent moieties which can be the same or different selected from the group consisting of alkyl, substituted alkyl, aryl, and substituted aryl;R.sup.3 are monovalent moieties which can be the same or different selected from the group consisting of alkyl, substituted alkyl, vinyl, aryl, and substituted aryl;R.sup.4 are monovalent moieties which can be the same or different selected from the group consisting of alkyl, substituted alkyl, vinyl, aryl, and substituted aryl; andn is an integer of about 270 to about 1000.A composition which is curable to a pressure sensitive adhesive comprising the above polymer and a sufficient amount of tackifier. Thhe invention also relates to fluorosilane compounds useful in the preparation of silicone macromonomer, their preparation and the preparation of silicone macromonomer.