The polymer has the formula ##STR5## where n is from about 300 to about 1,000, where R1 and R2 can be the same or different, where R1 and R2 is an alkyl group having from 1 to 8 carbon atoms with methyl being preferred, a cycloalkyl group having from 4 to 7 carbon atoms such as cyclohexyl, an alkenyl group having from 2 to 8 carbon atoms such as allyl with vinyl being preferred, an aryl or an alky