A composition in accordance with claim 39 wherein R1 is an alkyl, cycloalkyl, aryl, alkaryl or aralkyl group having from 7 to 21 carbon atoms; R2 is an alkylene group having 2 carbon atoms; R3 is an alkylene group having 2 carbon atoms; R4 is an alkylene group having 2 carbon atoms; x=1; y=1; m=1 and n=2 to 30.