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

Polynorbornene (PNB) or cyclo olefin copolymer (COC) can undergo conformational 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 COC. Interconversion between two major chain conformers leads to two groups of ¹³C NMR resonances corresponding to the CH carbon in the norbornene chain at 53 ppm (T(T)T + G(T)G) and 49 ppm (T(T)G). Chain reordering following the conversion leads to the condensation of the COC bulk and raises its T(g), substantially. The presence of random PE segment not only improves its segmental motion but also facilitates the conversion into the most stable T(T)G conformation.