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Dethreading during the preparation of polyrotaxanes
Author(s) -
Gong Caiguo,
Gibson Harry W.
Publication year - 1997
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1997.021980723
Subject(s) - diol , steric effects , condensation polymer , materials science , polymer chemistry , nanometre , two dimensional nuclear magnetic resonance spectroscopy , rotaxane , molecule , chemistry , stereochemistry , organic chemistry , polymer , supramolecular chemistry , composite material
Abstract Using a diol blocking group, bis( p‐tert ‐butylphenyl)bis[ p ‐(2‐(2‐hydroxyethoxy)ethoxy)phenyl]methane (diol BG 1 ), a diol with a sterically large core, copolysebacate 30‐crown‐10 (30C10) rotaxanes 8, 9 and 10 were synthesized by incorporating different amounts of 1,10‐decanediol. These copolymeric rotaxanes were characterized by different techniques, including proton NMR spectra, hydrolytic recovery of 30C10 and 2D NOESY. It was found that threaded 30C10 displayed a range of chemical shifts corresponding to the various sequence structures in which it was constrained. In addition, it was proved that the threading efficiency ( m/n value, the average number of cyclic molecules per repeating unit) increased with feed ratio of diol BG 1 vs. 1,10‐decanediol. A linear relationship of threading or dethreading degree vs. the percentage of diol BG in the total diol feed was revealed; more BG, less dethreading. The results demonstrate that dethreading occurs during the polycondensation in the absence of BGs.