Quantitatively Probing Cross‐Termination in RAFT Polymerization by an Externally Applied Magnetic Field

Abstract

Cross‐termination in bulk reversible addition–fragmentation chain transfer (RAFT) polymerization is characterized by defining a new parameter, RM, in terms of the polymerization rates with and without an externally applied magnetic field (EAMF). For the bulk RAFT polymerization (RAFTP) of styrene (St), mediated by (2‐cyano‐2‐propyl)dithiobenzoate (CPDB) and S‐1‐dodecyl‐S′‐(α, α′‐dimethyl‐α′′‐acetic acid)trithiocarbonate (DDMAT), an RM of 0.534 and 0.382 is obtained respectively, showing a sensible dependence on the RAFT agent. It is also found that RM has a close relationship with the strength of the EAMF and the concentration of the RAFT agent. Detailed discussion reveals that RM can be used as a characteristic parameter to measure the extent of cross‐termination in RAFTP. The experimental technique offers an efficient way to quantitatively probe the cross‐termination in situ, and sheds light on the mechanism of RAFTP. image