Characterization of New Amphiphilic Block Copolymers of N-Vinylpyrrolidone and Vinyl Acetate, 2 - Chromatographic Separation and Analysis by MALDI-TOF and FT-IR Coupling a Nick Fandrich,* Jana Falkenhagen, Steffen M. Weidner,* Bastiaan Staal, Andreas F. Thu ¨nemann, Andre ´ Laschewsky Introduction Recent investigations of amphiphilic N-vinyl pyrrolidone and vinyl acetate block copolymers (PVP-block-PVAc), synthesized via controlled radical polymerization, rever- sible addition fragmentation chain transfer (RAFT)/Macro- molecular Design via Interchange of Xanthates) (MADIX), showed strong differences between calculated and detected monomer ratios measured by NMR. [1] Additional size-exclusion chromatography (SEC) investigations revealed that blends of poly(N-vinylpyrrolidone) (PVP) and poly(vinyl acetate) (PVAc) homopolymers instead of block copolymers were formed. Chain transfer reactions between the initiator radicals and the RAFT agent as well between growing macroradicals and the process solvent were observed by means of matrix-assisted laser de- sorption/ionization time-of-flight (MALDI-TOF) mass spec- trometry (MS). These results led to the conclusion that the RAFT mechanism is strongly affected by side reactions. Although many different spectrometric and spectroscopic techniques had been used, it was not possible to distinguish between main and side products of the polymerization. [1] Thus, for a better understanding of the polymerization mechanism a detailed chromatographic investigation of Full Paper N. Fandrich, J. Falkenhagen, S. M. Weidner, A. F. Thu ¨nemann BAM – Federal Institute for Materials Research and Testing, Richard-Willsta ¨tter-Str. 11, D-12489 Berlin, Germany Fax: þ49 30 8104 1137; E-mail: steffen.weidner@bam.de, n.fandrich@guben.plastination.com N. Fandrich, A. Laschewsky University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam-Golm, Germany B. Staal BASF SE, GKP/P-G200, D-67056 Ludwigshafen, Germany a Part 1: cf. ref. [1] PVP-block-PVAc block copolymers were synthesized by controlled radical polymerization applying a RAFT/MADIX system and were investigated by HPLC and by coupling of chroma- tography to FT-IR spectroscopy and MALDI-TOF MS. Chromatographic methods (LACCC and gradient techniques) were developed that allowed a separation of block copolymers according to their repeating units. The results of the spectro- scopic and spectrometric analysis clearly showed transfer between radicals and process solvent. With the use of hyphenated techniques differ- ences between main and side products were detected. In agreement with previously published results, obtained by NMR, SEC, static light scatter- ing and MALDI-TOF MS, our data proved a non- ideal RAFT polymerization. 1678 Macromol. Chem. Phys. 2010, 211, 1678–1688 ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/macp.201000044