wherein N is a nitrogen atom and R is hydrogen or a substituted or unsubstituted alkyl or aryl attached to N, preferably wherein R is H. The average number of repeat units of the polymer chains is typically in the range of from about from about 10 to about 25,000, more typically in the range of from about 100 to 1,000, even more typically in the range of from about 125 to 500, and further typicall