Synthesis and molecular weight characterization of end-functionalized N-vinyl-2-pyrrolidone oligomers

New oligomers of N-vinyl-2-pyrrolidone, functionalized at one end with hydroxy functions, were obtained by radical polymerization in the presence of a hydroxylated compound, namely 2-isopropoxyethanol, acting as chain-transfer agent. The oligomeric samples obtained were characterized in terms of molecular weight and molecular weight distribution by means of analytical size exclusion chromatography (SEC). To this purpose, a calibration curve for a set of SEC columns had been determined, making use of poly(N-vinyl-2-pyrrolidone) standards purposely prepared. The chain transfer constant CT of 2-isopropoxyethanol towards N-vinyl-2-pyrrolidone was determined from the knowledge of the cumulated number-average degree of polymerization X̄n and monomer conversion Yt of the samples during the reaction.