. . . . "Preferably, R1, R2, R4, R5and R7 are independently hydrogen, or a linear or branched alkyl or alkenyl group having from 1 to about 6 carbon atoms, R6 is a linear or branched alkyl or alkenyl group having from about 8 to about 30 carbon atoms, m is 0 or 1, and R3 is a linear or branched alkylene having from 2 to about 22 carbon atoms." .