Unexpected reactions associated with the xanthate‐mediated polymerization of N‐vinylpyrrolidone

Abstract

The monomer N‐vinylpyrrolidone (NVP) undergoes side reactions in the presence of R group functional xanthates and impurities. The fate of the monomer NVP and a selection of six O‐ethyl xanthates during xanthate‐mediated polymerization were studied via NMR spectroscopy. A high number of by‐products were identified. Significant side reactions affecting NVP include the formation of an unsaturated dimer and hydration products in bulk or in solution in C6D6. In addition, the xanthate adjacent to a NVP unit was found to undergo elimination at moderate temperature (60–70 °C), resulting in unsaturated species and the formation of new xanthate species. The presence of the chlorinated compound α‐chlorophenyl acetic acid, ethyl ester, a precursor in the synthesis of the xanthate S‐(2‐ethyl phenylacetate) O‐ethyl xanthate, resulted in a dramatic increase in the rate of side reactions such as unsaturated dimer formation and a high ratio of unsaturated chain ends. The conditions for the occurrence of such side reactions are discussed in this article, with relevance to increasing the control over the polymerization kinetics, endgroup functionality, and control over the molar mass distribution. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6575–6593, 2008

Synthesis and Characterization of PDMS‐, PVP‐, and PS‐Containing ABCBA Pentablock Copolymers

“…Indicated on the spectrum are the large signals from the polymer segments, and also the signals from the thiocarbonyl group of the xanthate and the ester group that connects the PDMS and the PS segments. Our assignments in both the 1 H and 13 C NMR spectra are consistent with the extensive NMR work done on xanthate-based RAFT agents by Pound et al [32] The GPC trace of the dixanthyl triblock copolymer was essentially identical to the dibromo precursor (Figure 1), indicating that no coupling or other side reactions had taken place.…”

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

“…[5][6][7][8][9] Whereas esters have been used successfully in RAFT polymerizations of poly(VP-block-VAc) copolymers, the application of 2-propionic-acid as reinitiating leaving group (R-group) in the polymerization of VP represents a relatively new approach. [10] In the present work new VP-block-VAc-copolymers [poly(VP-block-VAc)] were investigated with regard to molar masses, block copolymer composition and end groups. These investigations are essential to get a deeper insight into the mechanism of polymerization, and to optimize the synthesis.…”

Poly( N -2-(methacryloyloxy)ethyl pyrrolidone)-poly(benzyl methacrylate) diblock copolymer nano-objects via RAFT alcoholic dispersion polymerisation in ethanol

“…Compared to related pyrrolidone-functional monomers such as N-vinyl pyrrolidone, [49][50][51][52][53][54] there are rather few literature reports describing the RAFT polymerisation of NMEP [45][46][47][48]. Thus, a detailed study of the kinetics of the RAFT solution homopolymerisation of PNMEP in ethanol at 70 °C was conducted.…”