"carboxyamidealkyl groups (containing independently hydroxyl groups, or secondary or tertiary amide linkages) attached via a carbon or oxygen; these may be (CH2)n CONHRa, O(CH2)n CONHRa, (CH2)n CON(Ra)2, or O(CH2)n CON(Ra)2 ; where n is a positive integer or zero, Ra is independently H, alkyl, hydroxyalkyl, saccharide, C.sub.(m-w) H.sub.[(2m+1)-2w] Ow Oz, O2 CC.sub.(m-w) H.sub.[(2m+1)-2w] Ow Oz or" . . . . .