Cyclic Polymers Based On UV-induced Strain Prompted Azide-alkyne Cycloaddition Reaction

It is well known that the structure determines properties of polymer. Compared with the linear polymer, the nonlinear polymer has more physical and chemical properties, including its phase behavior of ontology, the structure of the microfacies, solution properties and the self-assembly behavior, etc. Because of its unique properties, nonlinear polymer has many application prospects. At present, the living/controlled radical polymerizations have been reported, including the atom transfer radical polymerization(ATRP), reversible addition-fragmentation chain transfer polymerization(RAFT).In this article, cyclic polymer is prepared through UV-induced strain promoted azide-alkyne cycloaddition(SPAAC)reaction.First of all, the molecular structure of a new chain transfer agent synthesized contains a cyclic ketene diphenyl, a ring sheen acetylene and an azide group. By one-dimensional hydrogen nuclear magnetic spectrum, we knew the molecular structure of the chain transfer agent. By the 350 nm UV light and ultraviolet absorption spectrum, the activity and stability of the groups in chain transfer agent had been proved.Moreover, the linear polymer containing an azide group and a ring sheen acetylene was prepared by RAFT. By one-dimensional hydrogen nuclear magnetic spectrum, we knew the end groups of linear polymer in good condition. By gel permeation chromatograph(GPC), the activity of polymerization controllability was proved. By ultraviolet absorption spectra and IR spectra analysis, the ring ketene and azide were illustrated.Finally, the ring alkynyl of linear was got by the 350 nm UV light. Then the cyclic macromolecule was prepared by “azide and alkyne” cycloaddition. By nuclear magnetic, ultraviolet absorption spectra and IR spectra, the results showed that the cyclization reaction completed. The GPC showed the increased outflow time, decreased hydrodynamic volume and the success of the annular polymer’s preparation.By the RAFT polymerization combined with SPAAC, we get a new method of preparation of cyclic polymer.