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

Abstract

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.

Synthesis of an amphiphilic spiro‐multiblock copolymer via thiol‐ene click chemistry

“…Figure (a) shows the XPS spectra of S‐MBCP and polyrings comparing the difference in the bonding types. According to our previous study, the polyring was synthesized from the oxidation of 8‐shaped PS . The 8‐shaped PS in the polyring was connected through SS bond linkages.…”

“…Thus, the 8‐shaped PS (HS‐∞‐SH) with terminal thiol groups can be utilized in reactions with a number of terminal diene compounds (hydrothiolation) to synthesize various polymers and properties. Polymers with the capacity for reversible growth and dissociation can also be formed due to disulfide/thiol redox chemistry (e.g., Scheme ).…”

“…From the ratio of the integral of these two peaks, the degree of end‐functionality was found to be more than 91%. The 8‐shaped PS could be well characterized by 1 H NMR spectroscopy according to our previous report . In the 1 H NMR spectrum, the spiro‐MBCP was well assigned to the assumed chemical structure by referring to the spectra of the starting precursor polymers (8‐shaped PS residue [blue color] and PEG residue [orange color]).…”

“…8‐Shaped PS was synthesized through the combination of ATRP, azide end‐group modification, click reaction, and disulfide/thiol redox reactions. The detailed synthesis was described in our previous report . The structure of the 8‐shaped PS was confirmed using size‐exclusion chromatography (SEC) (Fig.…”

Glasses‐shaped triblock copolymer prepared by combination of atom transfer radical polymerization and ring opening polymerization

“…15 These synthetic and purification developments have allowed the synthesis of various topologies of cyclic polymers, such as tadpole-, [16][17][18] sun-, 19 8-, 20 dumbbell-, 21 and theta-shape. 22 Further, additional examples of multicyclic topologies of theta-shaped bicyclic, 23,24 cage-shaped tricyclic polymers, 25 polyring, 26 and spiro-multiblock 27 (co)polymers have been realized in our group.…”