Dynamic Polydisulfide Latex via Emulsion Ring‐Opening Polymerization of Cyclodisulfides

Aqueous emulsion ring‐opening polymerization (ROP) of disulfide macrocycles is reported. A polydisulfide latex is achieved with a solids content of 10 wt.%, an average particle diameter of 250 nm and a number‐average molar mass of 170 kDa. The process consists of two sequential steps. Firstly, a dynamic library of cyclic disulfides is generated in situ from a dithiol (3,6‐dioxa‐1,8‐octanedithiol) submitted to oxidation by hydrogen peroxide and simultaneous disulfide exchange. Then, the mixture of homologous cyclic oligomers spontaneously undergoes ROP, presumably by an anionic mechanism. The propagating thiolate active centers are prone to react with internal disulfide bonds (inter‐ and intramolecular transfer), resulting in broad distributions in molar mass and particle size. There is evidence that such polymerization involving large strainless disulfide rings is an entropy‐driven ROP. The polydisulfide latex can be depolymerized via thiol‐disulfide exchange reactions upon addition of an excess of the starting dithiol. The resulting mixture of low‐molar‐mass linear and cyclic disulfide species can be repolymerized in emulsion to reform the virgin latex.