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Indexed by:期刊论文

Date of Publication:2021-02-02

Journal:MACROMOLECULES

Volume:53

Issue:22

Page Number:9901-9905

ISSN No.:0024-9297

Abstract:The highly active and selective synthesis of polysulfites from sulfur dioxide (SO2) and epoxides is challenging because of the side reactions of the copolymerization process which produce cyclic sulfite esters or/and polyether or ether linkages incorporating into the copolymer. Herein, we report a novel approach to the synthesis of well-defined polysulfites through the alternating copolymerization of SO2 and epoxides catalyzed by simple organic ammonium salts under mild conditions. Both the cation and anion have strong effects on the catalytic activity and product selectivity. PPN-X (PPN = bis(triphenylphosphine)iminium; X = Cl, OAc, or 2,4-dinitrophenoxide) salts containing a bulky cation efficiently mediated this copolymerization at ambient temperature and under 1 atm SO2 pressure, yielding polysulfites with a high sulfite unit content, controlled molecular weight, and narrow polydispersity. In situ H-1 NMR studies suggested that a weak bonding interaction exists between cyclohexene oxide and SO2, in which SO2 acts as a Lewis acid and promotes epoxide activation. The sulfur-containing polymers are facilely synthesized from the readily available monomers, and their metal-free residues make such polymers suitable for applications in biological and electronic fields.