REENTRANT ISOTROPIC-PHASE IN A SUPRAMOLECULAR DISK-LIKE OLIGOMER OF 4-[3,4,5-TRIS(NORMAL-DODECANYLOXY)BENZOYLOXY]-4'-[(2-VINYLOXY)ETHOXY]BIPHENYL

The synthesis of 4-(3,4,5-tris(n-dodecanyloxy)benzoyloxy]-4'-[(2-vinyloxy)ethoxy]biphenyl (7), its cationic polymerization to poly{4-[3,4,5-tris(n-dodecanyloxy)benzoyloxy]-4'-[(2-vinyloxy)ethoxy]biphenyl} (8) with narrow molecular-weight distribution (M(w)M(n) less-than-or-equal-to 1.25) and relative number-average degrees of polymerization (DP) from 2.7 to 8, and the characterization of the resulting oligomers by a combination of techniques consisting of differential scanning calorimetry, thermal optical polarized microscopy, and X-ray scattering experiments are presented. Compound 8 with DP = 3.2-3.9 displays a crystalline phase and a columnar hexagonal ((PHI(h)) mesophase at higher temperatures. Compound 8 with DP almost-equal-to 5 exhibits a (PHI(h)), mesophase and a thermodynamically stable enantiotropic re-entrant isotropic (I(re)) phase. Compound 8 with DP>5 is isotropic. The phase behaviour of the oligomers is explained based on the self-assembling of the tapered structural units of 8 into a supramolecular disc-like architecture in which the polymer backbone is confined to the centre of the disc-like supramolecule. The disc-like supramolecular architectures are responsible for the generation of (PHI(h)), I(re), and isotropic phases. Various structural suggestions for the influence of the molecular weight of 8 on its phase behaviour are discussed.