Structural Differences between Polypentynoates Bearing Mesogenic Moieties Polymerized with RH Complex and WCl₆Catalysts. A¹³C-NMR and Raman Study

Abstract

Abstract Pentynoates containing mesogenic groups, i.e., HC[dbnd]CCH2CH2-COOR (R = dihydrocholesteryl and p-methoxybiphenyl) were stereoregularly polymerized using a Rh complex catalyst, [Rh(norbornadiene)Cl]2, in the presence of triethylamine as the cocatalyst. The structure of the polymer obtained was compared with that of an analogous polymer prepared using the metathesis catalyst WCI6 in dioxane by 13C-NMR and laser Raman spectroscopic methods. The data indicated that the polypentynoate polymerized with the Rh complex has a cis-transoid form which allowed us to observe the two clear carbon signals C[dbnd]CH of the main chain in the 13C-NMR spectrum. The polypentynoate prepared using the WCI6 catalyst was found to have the trans-transoid conjugation length with N c[dbnd]c ≉ 7, which did not allow observation of the clear carbon signals of the main chain in the 13C-NMR spectrum.