Impact of the RAFT/MADIX agent on protonated diallylammonium monomer cyclopolymerization with efficient chain transfer to monomer

We have studied applicability of reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) method to radical cyclopolymerization of protonated diallylammonium monomer, namely diallylammonium trifluoroacetate (DAATFA), occurring with efficient chain transfer to monomer reaction. The latter drives to a significant extent polymerization, noticeably setting molecular weight, MW, of polymers and their polydispersity (polydispersity index (PDI) = 2.8-3.0). For the first time, upon DAATFA polymerization in presence of RAFT ethylxanthogenacetic acid (xanthate) in aqueous solutions at 70 degrees C, the side chain transfer reaction was inhibited and control of the polydispersity was achieved, the PDI = 1.2-1.3. The structural characteristic of poly(diallylammonium trifluoroacetate) (PDAATFA) polymers was analyzed via H-1 and C-13 NMR and IFS FTIR (ATR) spectroscopy. It was proved that the structure of polymers obtained by RAFT polymerization fully corresponds to the polymers PDAATFA containing cationic pyrrolidinium links and trifluoroacetate-counterions. At the optimal xanthate concentrations, the main products are polymers with the end dithiocarbonate group, i.e. macro-RAFT PDAATFA. Static/dynamic light scattering, viscometry and ultracentrifugation were used for polymers characterization. Molecular weight was determined by two independent methods: static light scattering (M-w) and hydrodynamic parameters analysis (M-Dn). The PDI M-w/M-n was calculated on the basis of Fujita approach, using the determined distributions of sedimentation coefficients. The experimental number average molecular weights, M-n grow with polymerization time, 6700 g mol(-1) < M-n < 10500 g mol(-1), but did not correspond to the theoretical one. The rate of polymerization mediated by xanthate was shown to increase approximately twice in comparison to free-radical process that distinguishes DAATFA RAFT polymerization from other processes mediated by RAFT agent.