THE ROLE OF HYDROGEN-BONDING ON A HYDROXYLATED LIQUID-CRYSTAL, BIS[4-(5-HYDROXYPENTYLOXYCARBONYL)PHENYLENE] TEREPHTHALATE

Hydroxyl-terminated liquid crystalline 5-hydroxypentyloxycarbonyl)phen ylene]terephthalate (BHT) was prepared and compared with its non-hydro xylated analog, his [4-(pentyloxycarbonyl)phenylene]terephthalate (BPT ). BHT, with the possibility to form intermolecular hydrogen bonding ( H-bonding), has higher thermal transition temperatures (T-m and T-i) t han BPT. Infrared spectroscopy was applied to prove the existence of H -bonding for BHT. An X-ray diffraction study suggests that the smectic A (S-A) phase is the only phase existing for BPT but for BHT, an inte rdigitated layered structure was found to be mixed with the S-A phase. The formation of this interdigitated layered structure is mainly due to the intermolecular H-bonding between the terminal hydroxyl and the external ester groups in BHT.