Polyrotaxanes by in situ self threading during polymerization of functional macrocycles .2. Poly(ester crown ether)s.

Poly(ester crown ether)s were synthesized by direct condensation of bis(5-carboxy-m-phenylene)-(3x + 2)-crown-x, x = 6, 8 and 10 (1a, 1b and 1c) with bisphenols via the Higashi method. The formation of higher molecular weight poly(ester crown ether) 5 from the 32-membered crown ether 1c and bisphenol-A (2a) as compared to polyester 3 from 20-membered crown ether 1a and bisphenol-A, polyester 4 made from the 26-membered crown ether 1b and bisphenol-A (2a) and polyester 6 derived from 32-membered 1c and bis(p-t-butylphenyl)-bis(p-hydroxyphenyl)methane (2b) under identical conditions is believed to be the result of threading (rotaxane formation) in 5 but no or less threading in 3, 4 or 6; indeed polyester 3 provides a control because its macrocyclic component (1a) too small to be threaded, even by a polymethylene chain. Threading in 5 was undetectable through NOESY experiments. However, melt polymerization of bis(5-hydroxymethyl-m-phenylene)-32-crown-10 (7) with sebacoyl chloride (8) gave an insoluble, but swellable elastomeric material 9, a polyrotaxane network, as a result of more extensive in situ threading brought about by hydrogen bonding of the crown ether with the alcohol moieties in the more concentrated medium. (C) 1997 Elsevier Science Ltd.