Control over the relative reactivities of monomers in RAFT copolymerization of styrene and acrylic acid

Abstract

The relative monomer reactivities in the reversible addition–fragmentation chain transfer (RAFT) radical copolymerization of styrene (S) and acrylic acid (AA) in a solution of the polar solvent N,N-dimethylformamide are found to be dependent on the chemical nature of the RAFT agent. Polymeric RAFT agents based on polyacrylic acid enhance the difference in monomer reactivities (dithiobenzoate – r_AA = 0.09 ± 0.02, r_S = 3.5 ± 1.2, trithiocarbonate – r_AA = 0.08 ± 0.04, r_S = 3.03 ± 1.78) compared to low molecular weight RAFT agents (dibenzyl dithiobenzoate – r_AA = 0.14 ± 0.01, r_S = 1.00 ± 0.01, dibenzyl trithiocarbonate – r_AA = 0.08 ± 0.01, r_S = 0.85 ± 0.03). The opposite effect on the relative reactivity of acrylic acid is observed when polymeric RAFT agents based on polystyrene are used (dithiobenzoate – r_AA = 3.3 ± 0.4, r_S = 0.72 ± 0.05, trithiocarbonate – r_AA = 0.11 ± 0.01, r_S = 0.54 ± 0.03). In all the investigated systems the copolymers formed are characterized by narrow MWD due to the high efficiency of the chosen RAFT agents.