|243. Millard, P.-E.; Barner, L.; Stenzel, M.H.; Davis, T. P.; Barner- Kowollik, C.; Müller, A.H.E.: RAFT Polymerization of N-Isopropylacrylamide and Acrylic Acid under gamma-Irradiation in Aqueous Media, Macromol. Rapid Commun. 27, 821-828 (2006)|
The ambient temperature (20°C) reversible addition fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAAm) and acrylic acid (AA) conducted directly in aqueous media under γ-initiation (at dose rates of 30 Gy h-1) proceeds in a controlled fashion (typically, Mw/Mn < 1.2) to near quantitative conversions and up to number-average molecular weights of 2.5*105 g mol-1 for PNIPAAm and 1.1*105 g mol-1 for PAA via two water-soluble trithiocarbonate chain transfer agents, i.e. S,S-bis(α,α'-dimethyl-α"-acetic acid)trithiocarbonate (TRITT) and 3-benzylsulfanylthiocarbonylsulfanyl propionic acid (BPATT). The generated polymers were successfully chain extended, suggesting that the RAFT agents are stable throughout the polymerization process so that complex and well defined architectures can be obtained.