Novel Synthesis of Polymers with Well-Defined Structures Based on Selective Reaction of Cyclic Sulfides and Cyclic Ethers Catalyzed by Quaternary Onium Salts

Novel syntheses of polymers with well-defined structures were developed on the basis of he selective reactions of thiiranes and oxiranes with carboxylic esters or active chlorides using quaternary onium stilts. (1) A new type of reactive polymers with pendant chloromethyl groups was synthesized by polyaddition of difunctional thiiranes or oxiranes with various organic dichlorides. (2) Polysulfides with controlled molecular weight and narrow molecular weight distribution were synthesized by ring-opening polymerization of thiiranes with carboxylic acid derivatives as initiators and quaternary onium salts as catalysts, in which acyl-groups transfer to the propagating center in each propagation step. The ring-opening polymerization of thiiranes has an advantage in the synthesis of specific shaped polymers Such as star polymers and cyclic polymers. (3) Novel A-B type sequence-ordered copolymers were synthesized by alternating ring-opening polymerization of oxiranes with gamma-thiobutyrolactone, or of oxetane with cyclic carboxylic anhydrides. (4) Sequence-ordered polymers were successfully synthesized on the basis of a new concept-"transformation of Polymer backbones" using insertion of thiiranes and oxiranes into poly(S-thioester)s in the aforementioned reaction systems. The reaction mechanism and advantages of the reaction systems are also discussed.