Topologically Reversible Transformation of Tricyclic Polymer into Polyring Using Disulfide/Thiol Redox Chemistry

A polyring capable of reversible growth and dissociation is synthesized from a tricyclic polystyrene (PS) prepared by combining atom transfer radical polymerization of a 4-arm star-shaped PS and azide–alkyne click reactions. In the preparation of the tricyclic PS, a coupling agent containing a disulfide linkage is used in the click cyclization reaction. The reduction of the disulfide linkage in the tricyclic PS results in an 8-shaped PS with thiol groups which on oxidation leads to a high molecular weight polyring. The topology transformation between the polymers occurs via reversible redox reaction of disulfide/thiol. The high molecular weight of the polyring is realized due to the formation of flexible S–S linkage between the 8-shaped PSs. Their structures are confirmed by FT-IR, 1H NMR, SEC, and MALDI-TOF MS analyses. In addition, molecular weight control of the polyring according to polymer concentration has been confirmed through SEC analysis.