r 1; R2 is alkyl or substituted alkyl; R3 is H, alkyl or aryl; R4 is a divalent hydrocarbon group having between 2 and 10 carbon atoms; R5 is a group selected from H, aryl, organosilyl, or the reaction product of an isocyanate, esterifying reagent or etherification reagent with the hydroxyl product formed when R5 is H.