wherein R1 and R4 are independently hydrocarbyl or substituted hydrocarbyl groups having from 1 to about 30 carbon atoms or ???R5SR6, R2 in each of the x (R2O) groups is independently C2???C4 alkylene, R3 is hydrogen, or a linear or branched alkyl group having from 1 to about 4 carbon atoms, R5 is a linear or branched alkyl group having from about 6 to about 30 carbon atoms, R6 is a hydrocarbyl or