Introduction of end groups into cyclic poly(ether sulfone) by means of transetherification with bis(aryloxyphenyl) sulfone

Abstract End‐functionalized linear poly(ether sulfone) (PES) free from cyclic PES ( CPES ) was obtained by reversible transetherification of CPES with bis(aryloxyphenyl) sulfone 1 in the presence of base catalyst. Initially, transetherification of CPES with bis(phenoxyphenyl) sulfone 1a in the presence of a catalytic amount of CsF in N ‐methylpyrrolidone (NMP) at 145 °C afforded not the desired linear PES ( LPES ), but CPES with decreased molecular weight. However, when PhOSiMe 3 /K 2 CO 3 was used instead of CsF at 180 °C, the desired LPES with a phenoxy group derived from 1a at both ends was obtained. Under the established conditions, the transetherification of CPES with bis(bromophenoxyphenyl) sulfone 1b instead of 1a afforded not only LPES with a bromophenoxy group at both ends, but also LPES with a bromophenoxy group at one end and a phenoxy group at the other. Since the phenoxy group might be introduced from PhOSiMe 3 , the reaction was conducted with BrPhOSiMe 3 instead of PhOSiMe 3 along with K 2 CO 3 as a catalyst, and in this case, the desired LPES with a bromophemoxy group at both ends was obtained.