Pyridinyl Polythioether via a One-Pot Thiolactone Ring-Opening and Thiol-Phenylsulfone Click Polymerization: Synthesis, Fluorescence, and Degradation Behavior

In this study, we synthesized a heteroaromatic thioether-containing polymer through the ring-opening of N-acetyl homocysteine thiolactone (NHTL) and thiol-heteroaromatic sulfone click polymerization in a one-pot approach. A dithiol monomer, produced in situ via NHTL ring-opening, was polymerized with a bis(phenylsulfone)-containing monomer through the click step-growth polymerization, resulting in the generation of a thermally stable polymer with pyridinyl thioether moieties in its main chain. The obtained polymer demonstrated clustering-triggered emission behavior due to electron-rich N, O, and S heteroatoms in the polymer structure. It was explored as a fluorescent polymeric probe to detect Cu²⁺ ions in the visible region. With H₂O₂/Na₂WO₄ as the oxidative reagent, thioether moieties in the polymer backbone were converted to sulfoxide/sulfone moieties. The resulting oxidized polymer underwent degradation through a declick reaction with a monothiol-containing compound. After the declick reaction of 2-mercaptoethanol and the oxidized polymer, a small molecule readily separated from the degradation product was recycled as a diol monomer to prepare polyurethane with a diisocyanate monomer. The pyridinyl thioether-containing polymer with clustering-triggered emission behavior exhibits potential as a new degradable material that can address environmental concerns and enhance sustainability in various applications.