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 (DP n ) of the hyperbranched PDEMAB. A kinetic study showed that DP n 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, DP n increased much faster than when a higher ratio was used. The CuBr/2,2′‐bipyridine complex showed good catalytic activity while FeCl 2 /aliphatic multi‐amine complexes led to crosslinking. For the viscometry of the aqueous solution, although c 1/2 − (η sp / c ) −1 fitted well, the Füoss 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