LIQUID-CRYSTALLINE POLYETHERS BASED ON CONFORMATIONAL ISOMERISM .15. SMECTIC AND CRYSTALLINE PHASES IN COPOLYETHERS BASED ON 1,2-BIS(4-HYDROXYPHENYL)ETHANE AND COMBINATIONS OF 1,10-DIBROMODECANE WITH 1,12-DIBROMODODECANE AND OF 1,8-DIBROMOOCTANE WITH 1,12-DIBROMODODECANE

The synthesis and characterization of copolyethers based on 1,2-bis(4-hydroxyphenyl)ethane (BPE) and a 1/1 molar ratio of 1,10-dibromodecane with 1,12-dibromododecane [BPE-10/12(1/1)] and, respectively, BPE and a 1/1 molar ratio of 1,8-dibromooctane with 1,12-dibromododecane [BPE-8/12(1/1)] are described. A combination of techniques consisting of differential scanning calorimetry (DSC), simultaneous X-ray diffraction/DSC (XDDSC), and thermal optical polarized microscopy was used for the characterization of both copolymers. BPE-10/12(1/1) exhibits two orthorhombic crystalline (Cr and Cr') phases and an enantiotropic smectic B phase (probably the crystal B variant). In the Cr phase the spacers are crystalline, while in the Cr' phase they are in a molten state. BPE-8/12(1/1) exhibits an enantiotropic smectic B phase and an enantiotropic hexagonal columnar mesophase. Fibers drawn from BPE-10/12(1/1) orient the plane of the smectic layer parallel to the draw direction, suggesting that a substantial fraction of polymer chains form reentrant folds within the spacer layer. This result is contrary to findings in previous main-chain liquid crystalline polymers where the plane of the smectic layer aligns perpendicular to the draw direction.