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Molecular Motions in the Supramolecular Complexes between Poly( ε ‐caprolactone)‐Poly(ethylene oxide)‐Poly( ε ‐caprolactone) and α ‐ and γ ‐Cyclodextrins
Author(s) -
Lu Jin,
Mirau Peter A.,
Shin I. Daniel,
Nojima S.,
Tonelli Alan E.
Publication year - 2002
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 - 10.1002/1521-3935(20020101)203:1<71::aid-macp71>3.0.co;2-d
Subject(s) - caprolactone , copolymer , heteronuclear molecule , materials science , supramolecular chemistry , polymer chemistry , relaxation (psychology) , molecular dynamics , polymer , ethylene oxide , chemical physics , chemistry , crystallography , nuclear magnetic resonance spectroscopy , crystal structure , stereochemistry , computational chemistry , composite material , psychology , social psychology
The structure and molecular motions of the triblock copolymer PCL‐PEO‐PCL and its inclusion complexes with α ‐ and γ ‐cyclodextrins ( α ‐ and γ ‐CDs) have been studied by solid‐state NMR. Different cross‐polarization dynamics have been observed for the guest polymer and host CDs. Guest–host magnetization exchange has been observed by proton spin lattice relaxation T 1 , proton spin lattice frame relaxation T 1ρ and 2D heteronuclear correlation experiments. A homogeneous phase has been observed for these complexes. Conventional relaxation experiments and 2D wide‐line separation NMR with windowless isotropic mixing have been used to measure the chain dynamics. The results show that for localized molecular motion in the megahertz regime, the included PCL block chains are much more mobile than the crystalline PCL blocks in the bulk triblock copolymer. However, the mobility of the included PEO block chains is not very different from the amorphous PEO blocks of the bulk sample. The cooperative, long chain motions in the mid‐kilohertz regime for pairs of PCL‐PEO‐PCL chains in their γ ‐CD channels seem more restricted than for the single PCL‐PEO‐PCL chains in the α ‐CD channels, however, they are not influencing the more localized, higher frequency megahertz motions.