Caiguo Gong

Self‐Assembly of Novel Polyrotaxanes: Main‐Chain Pseudopolyrotaxanes with Poly(ester crown ether) Backbones

Not threading rings on chains, but chains through rings results in a new class of main-chain polyrotaxanes. The cations of bipyridinium salts thread through the crown ether units of a poly(ester crown ether) chain (shown below). The threading efficiency m/n of the polyrotaxane is controlled by stoichiometry and temperature.

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.

Polyrotaxanes and related structures: synthesis and properties

Abstract Significant advances in the polyrotaxane field have been made in the past year, in terms of understanding information mechanisms and the development of new materials. The highlights include the recognition of hydrogen-bonding as a driving force for the formation of crown ether-based polyrotaxanes, preparation of mechanically-linked branched and crosslinked polymers, and the development of polyrotaxanes with new architectures.