Aromatic disulfide polymers back to macrocyclic disulfide oligomers via cyclo-depolymerization reaction

A brand new and highly efficient method has been developed for the synthesis of aromatic macrocyclic disulfide oligomers. Cyclization was achieved by cyclo-depolymerization (CDP) of aromatic disulfide polymer in the presence of catalytic amount of thiols and weak base. The cyclic oligomers undergo a facile free-radical ring-opening polymerization to form high molecular weight polymer. Comparing with the conventional method for the preparation of macrocyclic aromatic oligomers by catalytic oxidation of dithiols, highly dilute condition was not necessary using the new method. The macrocyclics in high yield and with narrow molecular weight distribution were obtained. This method also provides a convenient technology for the recycle of aromatic disulfide polymers. [GRAPHICS] (c) 2005 Elsevier Ltd. All rights reserved.