Mechanistic Investigations on the Formation of Supramolecular Cylindrical Shaped Oligomers and Polymers by Living Ring Opening Metathesis Polymerization of a 7-Oxanorbornene Monomer Substituted with Two Tapered Monodendrons

Abstract

The synthesis of the monomer exo,exo-5,6-bis[[[(3,4,5-tris((4-(dodecyl-1-oxy)benzyl)oxy)]benzyl)oxy]carbonyl]-7-oxabicyclo[2.2.1]hept-2-ene (4), containing two tapered monodendrons and its living ring-opening metathesis polymerization initiated with RuCl2(CHPh)(PCy3)2 are discussed. Oligomers and polymers with narrow molecular weight distribution (Mw/Mn = 1.06−1.29) and degrees of polymerization (DP) from 6 to 120, which correspond to Mn from 12 600 to 252 800, were synthesized and characterized. The monomer (4) and the corresponding polymers (5) self-assemble into disklike and cylindrical shapes which produce an enantiotropic hexagonal columnar (Φh) liquid crystalline (LC) phase. The analysis of the Φh phase of the monomer, oligomers, and polymers as a function of the DP reveals four regions and mechanisms for the generation of the Φh phase, i.e., below the DP which forms a disklike molecule, below the DP which corresponds to the maximum length of a disklike molecule (DP = 26), up to the DP which corresp...