標題: Conformational conversion and local packing of cyclic olefin copolymers
作者: Chu, PPJ
Cheng, MH
Huang, WJ
Chang, FC
應用化學系
Department of Applied Chemistry
公開日期: 12-Dec-2000
摘要: Cyclic olefin copolymer (COC, poly(norbornene-co-ethylene)) catalyzed by ansa-ethylenebis-(indenyl)zirconium dichloride (Et[Ind](2)ZrCl2)/methylaluminoxane (MAO) gives rise to phenomenal increase of T-g upon annealing. Unaveraged solid-state C-13 NMR resonance of the CH carbons in the norbornene (53 and 49 ppm) evidenced the conformation conversion from T[X]T and G[M]G to more stable T[X]G conformers (where [X] = [T] or [G] represent the norbornene chain conformation). As the persistent length increases with the conversion, local packing of the rigid chain subsequently occurs. Synchrotron source X-ray diffraction provides clear evidence of the averaged interchain contraction from 12.0 to 8.5 Angstrom and a tighter distribution in the spacing after annealing. In the preannealed state, T-1p(H) relaxation time revealed both mobile (where conformer converts) and rigid components (where conformation is frozen), which coalesce into a further rigid component after extended annealing. The mechanisms governing the packing in amorphous COC are likely by the random chain diffusion and not from cooperative motion as described by the bundle-packing model.
URI: http://dx.doi.org/10.1021/ma000494k
http://hdl.handle.net/11536/30051
ISSN: 0024-9297
DOI: 10.1021/ma000494k
期刊: MACROMOLECULES
Volume: 33
Issue: 25
起始頁: 9360
結束頁: 9366
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