Conformational conversion and chain ordering in cycle olefin copolymer (COC)

Polynorbornene (PNB) or cycle olefin copolymer (COC) can undergo conformati onal conversion into the more stable T(T)G conformer from T(T)T and G(T)G. The conversion constitutes the nascent stage for the reordering process of the COG. Interconversion between two major chain conformers leads to two gr oups of C-13 NMR resonances corresponding to the CH carbon in the norbornen e chain at 53 ppm (T(T)T + G(T)G) and 49 ppm (T(T)G). Chain reordering foll owing the conversion leads to the condensation of the COC bulk and raises i ts T-g, substantially. The presence of random PE segment not only improves its segmental motion but also facilitates the conversion into the most stab le T(T)G conformation. (C) 1999 Elsevier Science Ltd. Ail rights reserved.