ISOMORPHISM WITHIN THE HEXAGONAL COLUMNAR MESOPHASE OF MOLECULAR AND MACROMOLECULAR SELF-ASSEMBLED AND CO-ASSEMBLED COLUMNS CONTAINING TAPERED GROUPS

The phase behaviour of binary mixtures of self-assembled tapering mole cules based on monoesters of oligooxyethylene glycol and 3,4,5-tris[4- (n-dodecan-1-yloxy)benzyloxy]benzoic acid, their corresponding polymet hacrylates, and of 4'-methyl 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy ]benzoate within their hexagonal columnar mesophase (PHI(h)) is descri bed. The binary blends between molecular tapers co-assemble into a sin gle supramolecular column resulting in isomorphism within their PHI(h) mesophase over the entire range of composition. The binary blends bet ween polymethacrylates containing tapered side groups co-assemble into a single PHI(h) phase only when the columns of the parent polymers ar e of similar diameters. This results in binary mixtures which are isom orphic within the PHI(h) mesophase over the entire composition range. When the diameters of the columns formed by the parent polymers are di ssimilar, isomorphic mixtures are obtained only over a narrow range of composition. Binary mixtures between molecular tapers and macromolecu lar systems containing tapered side groups co-assemble into a single c olumn to the extent that intercalation of the molecular taper, within the column formed by the macromolecular system containing tapered side groups, is permissible. In all systems increased intra-columnar inter actions can be induced by complexation of CF3SO3Li by the oligooxyethy lenic receptors leading to isomorphism in otherwise non-isomorphic mix tures. Ternary mixtures between molecular tapers with non-specific oli gooxyethylenic receptors and specific crown ether receptors and CF3SO3 Na as the third component are non-isomorphic within their PHI(h) phase due to preferential complexation of the alkali metal cation by the co lumn of the crown ether containing the molecular taper. This results i n two columns of dissimilar diameters, which are isomorphic in the PHI (h) phase only within a limited range of composition.