Characterization of New Amphiphilic Block Copolymers of N-Vinyl Pyrrolidone and Vinyl Acetate, 1 - Analysis of Copolymer Composition, End Groups, Molar Masses and Molar Mass Distributions

New amphiphilic block copolymers consisting of N‐vinyl pyrrolidone and vinyl acetate were synthesized via controlled radical polymerization using a reversible addition/fragmentation chain transfer (RAFT)/macromolecular design via the interchange of xanthates (MADIX) system. The synthesis was carried out in 1,4‐dioxane as process solvent. In order to get conclusions on the mechanism of the polymerization the molecular structure of formed copolymers was analysed by means of different analytical techniques. 13C NMR spectroscopy was used for the determination of the monomer ratios. End groups were analysed by means of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. This technique was also used to determine possible fragmentations of the RAFT end groups. By means of a combination of size exclusion chromatography, 13C NMR and static light scattering molar mass distributions and absolute molar masses could be analysed. The results clearly show a non‐ideal RAFT mechanism. Amphiphilic block copolymers are a special class of polymers. In the present paper new polymers of this type containing N‐vinyl pyrrolidone units as water soluble sequences are characterized at molecular level. Beside expected polymer structures resulting from the RAFT synthesis unexpected end groups were found indicating a non‐ideal mechanism of polymerization.