Summary: 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, < 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 are successfully chain extended, which suggests that the RAFT agents are stable throughout the polymerization process so that complex and well‐defined architectures can be obtained.
An increase of the monomer/CTA ratio leads to an increase of the molecular weight for the RAFT polymerization of NIPAAm under γ‐radiation in water using TRITT at ambient temperature.
