Sequential Michael addition thiol–ene and radical-mediated thiol–ene reactions in one-pot produced sequence-ordered polymers

Abstract

Sequential Michael addition-based thiol–ene and free radical mediated thiol–ene reactions for preparing sequence-ordered polymers are reported for the first time. The thiols are produced in situ via the ring-opening of thiolactones, and they can readily react with the electron-deficient carbon–carbon double bond of allyl methacrylate via Michael addition-based thiol–ene, but they are unable to react with the electron-rich carbon–carbon double bond of allyl methacrylate without radicals, and intermediates with thiol and alkene units are formed. After the Michael addition thiol–ene and ring-opening reactions are complete, the thiol is activated by UV irradiation, enabling reaction with the electron-rich carbon–carbon double bond via a free radical-mediated thiol–ene reaction, to form sequence-ordered polymers of high molecular weights.