LIQUID-CRYSTALLINE POLYMERS CONTAINING MESOGENIC UNITS BASED ON HALF-DISK AND RODLIKE MOIETIES .5. SIDE-CHAIN LIQUID-CRYSTALLINE POLY(METHYLSILOXANES) CONTAINING HEMIPHASMIDIC MESOGENS BASED ON 4-[[3,4,5-TRIS(ALKAN-1-YLOXY)BENZOYL]OXY]-4'-[[PARA-(PROPAN-1-YLOXY)-BENZOYL]OXY]BIPHENYL GROUPS

The synthesis of hemiphasmidic monomers 4-[[3,4,5-tris[[(S)-(-)-2-methylbutan-1-yl]oxy]benzoyl]oxy]-4'-[[p-(allyloxy)benzoyl]oxy]biphenyl (14),4-[[3,4,5-tris(n-pentan-1-yloxy)benzoyl]oxy]-4'-[[p-(allyloxy)benzoyl]oxy]biphenyl (15), and 4-[[3,4,5-tris(n-dodecan-1-yloxy)benzoyl]oxy]-4'-[[p-(allyloxy)benzoyl]-oxy]biphenyl (16) and of the corresponding poly(methylsiloxanes) (17-19) is described. Both monomers and polymers were characterized by a combination of DSC, WAXS, SAXS, and thermal optical polarized microscopy. 15-17 are crystalline. 17 exhibits an enantiotropic double-layer smectic A or C mesophase. 18 displays a monotropic columnar hexagonal and an enantiotropic double-layer smectic A or C mesophases. Due to its close proximity to the glass transition temperature, the columnar hexagonal phase of 18 is strongly kinetically controlled. 19 exhibits a very broad enantiotropic hexagonal columnar mesophase. The columns of the mesophases of 18 and 19 are generated by an elongated polymer backbone penetrating through the center of the column and tapered extended mesogens radiating out of it.