Tadpole-shaped polymers based on UV-induced strain promoted azide-alkyne cycloaddition reaction

In the present study, we synthesized well-defined tadpole-shaped polystyrene （PS） via the combination of atom transfer radical polymerization （ATRP） and UV-induced strain promoted azide-alkyne cycloaddtion （SPAAC） reaction. A di-bromo ATRP initiator （Br-ini-Br） containing cyclopropenone-masked dibenzocyclooctyne group was used to prepare the linear PS with a cyclopropenone-masked dibenzocyclooctyne in the middle of the chain and bromo groups at both ends （Br-PS-Br）. Then we used the single electron transfer-nitroxide radical coupling （SET-NRC） reaction to transfer the bromo end groups to azide groups （N3-PS-N3）. After UV irradiation, the dibenzocyclooctyne group was quantitatively released, and intramolecularly reacted with alternative azide end group to produce the tadpole-shaped PS based on SPAAC reaction.