Aqueous RAFT polymerization of N-isopropylacrylamine in the presence of oxygen at room-temperature

RAFT polymerization of N-isopropylacrylamide(NIPAM) in aqueous solution at room-temperature in the presence of oxygen was conducted by using K2S2O8/Na2S2O3 redox initiator and triethanolamine(TEA) as the additive.The polymers obtained were characterized by GPC.The molecular weight of the polymer linearly increases with the conversion and molecular weight distribution is narrow(Mw/Mn≤1.0).The linear time dependence of ln([M]0/[M]) indicates a first order polymerization.Moreover,the chain extension polymerization demonstrated that the molecular weight of the macro-chain transfer agents linearly increases with monomer conversion.All the facts indicate that the polymerization exhibits living characteristics.Moreover,the polymerization rate increases with temperature in the range of 25~35 ℃.And the polymerization can be performed at a relatively high rate at room-temperature and in the presence of oxygen.