Physically crosslinked elastomers prepared from oligomeric polyolefins with mesogenic units

Abstract

Two ABA-type liquid crystalline oligomers were newly synthesized, where A was a mesogenic group and B was polyolefin whose molecular mass was 2470. The A segment was prepared from p-hydroxyl benzoic acid and terephalic acid. The elastomeric films, whose moduli at 20% elongation were 0.4–1.0 MPa, were obtained by solution casting of the ABA-type oligomers. Dynamic mechanical analysis and differential scanning calorimetry measurement showed the glass transition of amorphous polyolefin segments, the melting of mesogenic groups, and the meso-to-isotropic transition of liquid crystalline phase. The formation of microphase-separated structures was confirmed by a small-angle X-ray scattering (SAXS) measurement. The presence of hexagonal cylinder domains, which were attributed to the aggregation of mesogenic groups in the polyolefin matrix, was also detected by SAXS. These liquid crystalline oligomers showed anisotropy under the crossed Nicoles, and the textures were observed to be nematic. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2247–2253, 2000