Synthesis, liquid crystallinity, and mechanical properties of thermotropic polyquinolines

Thermotropic liquid-crystalline polyquinolines with high molecular weights, i.e., poly[2,2'-(alpha,omega-dioxyphenylene (or -dioxybiphenylene) alkane)-6,6'-(4,4'-dioxybiphenyl)-bis (4-phenylquinoline)]s (P-H-B1Mns or P-H-B2Mns), were synthesized by polycondensation of 4,4'-bis(4-amino-3-benzoylphenoxy)biphenyl and alpha,omega-bis(4-acetophenoxy (or -acetobiphenoxy))alkanes. For P-H-B1Mn series, the T-m and T-i were in the range of 129-230 degrees C and 156-254 degrees C, respectively, while for the P-H-B2Mn series, those were 182-275 degrees C and 217-309 degrees C, respectively. The introduction of both the dioxybiphenylene group and an alkylene spacer induced thermotropic liquid crystallinity in the polyquinoline, although the introduction of the alkylene spacer alone did not induce it. In addition, polyquinolines substituted with methyl, methoxy, and chloro groups exhibited larger mesophase temperature ranges as well as higher T(m)s and T(i)s than the unsubstituted ones. Tensile strengths of these thermotropic polyquinolines were considerably high in the range of 770 to 1170 kgf/cm(2). (C) 1998 John Wiley & Sons, Inc.