adipate. The yielded PEO with two ion pairs was finally fixed at 130
C to form the
stable cyclic PEO, as shown in Scheme 9. The polymer was purified by preparative
size-exclusion chromatography (SEC) and confirmed by SEC and MALDI-TOF MS.
Scheme 8 Synthesis of cyclic poly(THF) by an electrostatic self-assembly and covalent fixation
(ESA-CF) process
Fig. 4 Various cyclic polymers synthesized by ESA-CF
Scheme 9 Synthesis of cyclic poly(ethylene oxide) by ESA-CF
Synthesis of Cyclic Polymers via Ring Closure
307