Diselenide-Labeled Cyclic Polystyrene with Multiple Responses: Facile Synthesis, Tunable Size, and Topology.

Diselenide-containing polymers have attracted more and more attention due to their redox sensitivity and bioapplication. In this work, a bifunctional diselenocarbonate is prepared and used to mediate the reversible addition-fragmentation chain transfer (RAFT) polymerization, producing α,ω-selenocarbonate-labeled telechelic polystyrene. Based on effective aminolysis of the terminal selenocarbonates and the followed spontaneous oxidation coupling reaction of diselenols, monoblock cyclic polystyrene linked by one diselenide bond and multiblock cyclic copolymer linked by several diselenide bonds are prepared by manipulating the concentration of α,ω-telechelic polystyrene in solution. The progress of aminolysis and the subsequent spontaneous oxidation of selenols to diselenides are monitored by UV-vis, gel permeation chromatography (GPC), and NMR characterizations, confirming the cyclic topologies of the resultant polymers (monocyclic or multiblock cyclic polymer). The monoblock cyclic or multiblock polymers show redox sensitivity, which can be converted to linear polymer by reducing or oxidizing agent. Moreover, the obtained monoblock cyclic polymer or multiblock cyclic copolymer can be transformed to each other under UV irradiation by adjusting the concentration of the cyclic polystyrene. For the first time, this work provides an alternative and promising approach to realize the topological transformation of polymers by installing multiresponsive diselenide moities into the backbone of cyclic polymer.