Liquid-crystalline polyethers based on conformational isomerism. Part 22—Hexagonal columnar mesophase in polyethers and copolyethers based on 1,4-bis[2-(4-hydroxyphenyl)ethyl]benzene, 1,2-bis(4-hydroxyphenyl)ethane and 1,9-dibromononane

Abstract

The syntheses of the following compounds are presented: 1,4-bis[2-(4-hydroxyphenyl)ethyl]benzene (PEB); polyethers based on PEB and α,ω-dibromoalkanes (PEB-X, where X represents the number of methylene units in the flexible spacer, i.e. X= 5, 7, 8, 9, 10 and 12); polyethers based on 1,2-bis(4-hydroxyphenyl)ethane (BPE) and 1,9-dibromononane (BPE-9); copolyethers based on 1,9-dibromononane with various ratios of BPE to PEB [BPE/PEB(A/B)-9, where A/B is the molar ratio of BPE to PEB]. The phase behaviour of these polymers was characterized by a combination of techniques consisting of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and thermal optical polarized microscopy. The high-temperature mesophase of all homopolymers and copolymers is hexagonal columnar (Φ_h). The temperature and the corresponding thermo-dynamic parameters of the i–Φ_h phase transition of BPE/PEB(A/B)-9 copolymers display continuous linear dependences of composition. The d₁₀₀^hex of the hexagonal columnar phase of the copolymers BPE/PEB(A/B)-9 determined at 150 °C is independent of copolymer composition.