One-pot synthesis of soluble wholly aromatic liquid crystalline copoly(ester amide)s with high thermal and dimensional stability

Abstract

Thermotropic liquid crystalline polymers (LCPs) have been of great interest for electronic packaging. Herein, we introduce a series of wholly aromatic, thermotropic LCPs from copoly(ester amide)s of 6-hydroxy-2-naphthalic acid, isophthalic acid, terephthalic acid, and 4-aminophenol, prepared by a convenient one-pot melt polycondensation. Almost synthesized copoly(ester amide)s exhibited good solubility in common organic solvents at room temperature. Furthermore, they possessed high thermal stability with 2% degradation temperatures (Tid) of 359–368 °C and the char yields (at 600 °C) of 50.3–55.6%. The synthesized copoly(ester amide)s had relatively low coefficient of thermal expansion (CTE) values, which were 35.85–41.21 ppm °C−1 in the temperature range of 50–200 °C. Furthermore, an annealing process could be employed to improve the thermomechanical properties of synthesized polymers. For instance, the CTE of sample LCP3 in range temperature of 275–315 °C was reduced by more than 90% after annealing at 320 °C for 1 h, implying the feasibility for electronic packaging.