William S. Bryant

POLYROTAXANES BY IN SITU SELF THREADING DURING POLYMERIZATION OF FUNCTIONAL MACROCYCLES. PART 2 : POLY(ESTER CROWN ETHER)S

Abstract 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.