New ester and lactone end-functionalized N-vinyl-2-pyrrolidinone oligomers

New oligomers of N-vinyl-2-pyrrolidinone functionalized at one end with eit her ester or lactone functions were obtained by radical polymerization in t he presence of different ester (methyl isobutyrate and methyl phenylacetate ) and lactone (epsilon-caprolactone, delta-valerolactone and gamma-btyrolac tone) compounds as chain transfer agents. The oligomeric samples obtained w ere characterized in terms of molecular weight and molecular weight distrib ution by means of analytical size exclusion chromatography (SEC), using pur posely synthesized poly(N-vinyl-2-pyrrolidinone) standards. The chain trans fer constant C-tau of either methyl isobutyrate, delta-valerolactone, or ga mma-butyrolactone towards N-vinyl-2-pyrrolidinone were determined with the help of the known cumulative number-average degree of polymerization (X) ov er bar(n) and monomer conversion Y-t of the samples during the reaction.