Thiol-benzoxazine chemistry as a novel Thiol-X reaction for the synthesis of block copolymers

- A new thiol-X coupling reaction based on the ring opening of benzoxazine molecules with thiols is demonstrated.
- Its applicability on block copolymer formation of PS with PMA or PEG is shown.
- The ease of benzoxazine synthesis and its design flexibility also are additional advantages in targeting polymers in such way.

A novel synthetic procedure is reported for the preparation of block copolymers by means of successive 1,3-benzoxazine-thiol and Husigen type azide-alkyne coupling methodologies in one-pot and sequential synthesis. The applied 1,3-benzoxazine-thiol process based on catalytic opening of the lateral benzoxazine rings by thiols is proposed as a new thiol-X chemistry. Azide functional poly(methyl acrylate) (PMA-N3), poly(ethylene glycol) (PEG-N3) and thiol functional polystyrene (PS-SH) were prepared. The obtained PMA-N3 or PEG-N3, PS-SH and propargyl benzoxazine as a click-linker were reacted in sequential or one-pot two step manner to yield desired PS-b-PMA and PS-b-PEG block copolymer. The described thiol-benzoxazine chemistry offers a facile and efficient route to exploring the many possibilities in macromolecular synthesis.