Synthesis and characterization of novel thermotropic liquid crystalline copoly(ester imide)s

✍ Scribed by Tsia-Fa Hsu; Yu-Chih Lin; Yu-Der Lee

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 384 KB
• Volume: 36
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199808)36:11<1791::aid-pola13>3.0.co;2-9

✦ Synopsis

Novel liquid crystalline copoly(ester imide)s were synthesized via polyesterification of triethyleneglycol bis(4-carboxyphenyl) ether ( 1e), diacetoxybiphenyl, and diacids with imide moieties. The effects of composition on the changes of T g , T m , and T i were examined by global TSC and DSC. Thermal gravimetric analyses (TGA) found that 4a-d and 5a-g possess higher thermal stability. Strong stir opalescence phenomenon and observations from polarized optical microscopy identified that 2b-e and 3a-d possess the typical schlieren texture of an enantiotropic nematic mesophase. The birefrigent melts of 4a-d and 5a-g, however, displayed particular liquid crystalline behavior. Copolymers with higher aromatic imide ring content (4a-d, 5a-g) form a layered structure and an enantiotropic smectic mesophase in the melting state. The melt viscosity of the semetic mesophase was higher than the nematic mesophase which was observed by capillary rheometer.