Aqueous self-condensing atom transfer radical copolymerization of a water-soluble inimer with cationic comonomer to prepare hyperbranched cationic polyelectrolytes

BACKGROUND: Although several methods have been reported for the preparation of hyperbranched cationic polyelectrolytes (HCPs), their applicability is limited. A convenient, facile strategy based on atom transfer radical polymerization (ATRP) of N,N-dimethyl-N-(2-methacryloyloxy)ethyl(2-bromoisobutyryloxy)ethylammonium bromide (DMEAB) with N,N-dimethyl-N-ethyl-N-methacryloyloxyethylammonium bromide (DEMAB) is therefore proposed to prepare their hyperbranched copolymer (PDEMAB). RESULTS: NMR spectroscopy was used to confirm the hyperbranched architecture and to estimate the number-average degree of polymerization (DPn) of the hyperbranched PDEMAB. A kinetic study showed that DPn of the hyperbranched PDEMAB increased very slowly in the initial stage, but increased in an exponential manner during the later phase. When a lower [DEMAB]:[DMEAB] ratio was used, DPn increased much faster than when a higher ratio was used. The CuBr/2,2′-bipyridine complex showed good catalytic activity while FeCl2/aliphatic multi-amine complexes led to crosslinking. For the viscometry of the aqueous solution, although c1/2 − (ηsp/c)−1 fitted well, the Fuoss equation might not be applicable for HCPs. A rheological study showed that the HCPs exhibited an extremely low viscosifying effect, in contrast to their linear analogues. CONCLUSION: The aqueous self-condensing ATRP of DMEAB with DEMAB (and other counterparts) readily led to HCPs. Such a strategy could also be extended to other monomers such as vinylpyridine and vinylimidazole. Copyright © 2009 Society of Chemical Industry