Phase Transition and Transition Kinetics of a Thermotropic Poly(amide−imide) Derived from 70 Pyromellitic Dianhydride, 30 Terephthaloyl Chloride, and 1,3-Bis[4-(4‘-aminophenoxy)cumyl]benzene

Abstract

The phase transition and transition kinetics of a liquid crystalline copoly(amide−imide) (PAI37), which was synthesized from 70 mol % pyromellitic dianhydride, 30 mol % terephthaloyl chloride, and 1,3-bis[4-(4‘-aminophenoxy)cumyl]benzene, was characterized by differential scanning calorimetry, polarized light microscopy, X-ray diffraction, and rheology. PAI37 exhibits a glass transition temperature at 182 °C followed by multiple phase transitions. The crystalline phase starts to melt at ∼220 °C and forms smectic C (SC) phase. The SC phase transforms into smectic A (SA) phase when the temperature is above 237 °C. The SC to SA transition spans a broad temperature range in which the SA phase vanishes and forms isotropic melt. The WAXD fiber pattern of PAI37 pulled from the anisotropic melt revealed an anomalous chain orientation, which was characterized by its layer normal perpendicular to the fiber direction. The transition kinetics for the mesophase and crystalline phase formation was also studied.

Influence of structural modification on the properties of poly(amide–imide)s

“…Aromatic poly(amide–imide)s (PAIs) have been considered as one class of high-performance polymer possessing amide and imide groups in the main chain. 1 –10 It is generally recognized that amide groups could increase the solubility, and the aromatic imide groups are beneficial to provide good mechanical and thermal properties. Ideally, PAIs could possess good mechanical and thermal properties of polyimides as well as ease of processability of polyamides.…”

An entropy-driven ring-opening metathesis polymerization approach towards main-chain liquid crystalline polymers

“…As illustrated in Fig. 1A, most of the previously reported MCLCPs were prepared using step-growth polycondensation reactions, such as polyesterification, 8,9 polyamidation, 10,11 polyurethanation, 12 palladium-catalyzed coupling reactions (i.e. Suzuki, 13 Heck, 14 Stille 15 couplings), hydrosilylation polyaddition, 16 thiol-ene polyaddition [17][18][19] and acyclic diene metathesis polymerization (ADMET).…”