Poly(ß-hydroxy thioether)s: synthesis through thiol-epoxy ‘click’ reaction and post-polymerization modification to main-chain polysulfonium salts

The base-catalyzed reaction between thiol and epoxide functionalities is a simple process that can be carried out under ambient conditions. The base catalyst can be organic or inorganic. The reaction medium can be organic or aqueous. A variety of the required mercapto/oxirane-containing building blocks can be obtained from commercial sources. The reaction is highly efficient and regioselective. It is due to these attributes the thiol-epoxy reaction is referred to as a ‘click’ reaction. It produces a ß-hydroxy thioether linkage upon completion. The thioether group can be modified by a post-polymerization alkylation reaction to access antibiofouling and antibacterial ß-hydroxy sulfonium salts. Overall, therefore, the thiol-epoxy reaction is highly utilitarian in the context of polymer synthesis. Our aim in this article is to trace our own steps in this area of research and document the journey from initial simple synthetic efforts to the current functional materials prepared by the thiol-epoxy ‘click’ reaction.