. . . . . . " an integer between 0 and 20, inclusive, and one or more of the methylene groups is optionally replaced by oxygen atom, a carbonyl group, urethane, urea, an ester group, a ???NR3 group, a CHR4 group, or a CR5R6 group where R3, R4, R5, and R6 are, independently, H, an alkyl group, or an aryl group; and Y is a bond, carbon atom, nitrogen atom, oxygen atom, sulfur atom, a branched or linear ???(CH2)p" . . . .