Novel polymers of general formula: ##STR1## wherein where n is a whole number from 2 to 10; R is a spacing group comprising (a) at least one of m methylene units where m is a whole number from 1 to 20, m' methine units where m' is a whole number from 0 to 20, a mixture of m methylene units and m' methine units where m+m'.ltoreq.20, and units of formula --(CH.sub.2 -CHX-O).sub.m" --, where m" is a whole number from 0 to 200 and X is H, CH.sub.3 or C.sub.2 H.sub.5, or (b) an aromatic ring having one, two or three members; R' is H, an alkyl group having no more than 20 carbon atoms, an aryl group having no more than three rings, or a combination thereof; R" is a group containing at least two active hydrogen atoms and having at least two but no more than 20 carbon atoms; and R'" is a group containing at least two active hydrogen atoms and is selected from the group consisting of alkyl, aryl and mixed alkyl-aryl species having from 1 to 200 carbon atoms; polyalkylene oxides; and urea formaldehyde resin.