Thermotropic Liquid-Crystalline Copoly(ester amide) Containing a Flexible Spacer in the Main Chain

Abstract

ABSTRACT:Thermotropic behavior was observed in a number of aromatic copoly(ester amides) containing a flexible spacer based on 4,4'-dicarboxyl-1,10-diphenoxydecane, di-acetylated p-aminophenol and di-acetylated hydroquinone with or without di-acetylated aromatic diamine. The copoly(ester amide) was synthesized by melt polycondensation accompanied by the removal of acetic acid. The introduction of up to 50mol% of p-aminophenol units, i.e., 25 mo!% of the amide group, gave thermotropic liquid crystalline copoly(ester amide), though the thermotropic behavior disappeared at a greater concentration of p-aminophenyl units. A thermotropic copoly(ester amide) was prepared with p-phenylenediamine, 4,4'-diaminodiphenylmethane or 4,4'-diamino-3,3'-dimethoxylbiphenyl as an amino group-containing monomer when it was used together with paminophenol as an essential amino-monomer. In the last case, up to 60 mo!% of amide groups was allowed to afford thermotropic liquid crystallinity. The polymer structure and thermotropic nature were examined by solid-state and solution 13 C NMR spectroscopy, differential scanning calorimetry, polarizing microscopy, and IR spectroscopy.KEY WORDS Copoly(ester amide) / Melt Polycondensation / Thermotropic Liquid Crystallinity / Amide Group/ Solid-State 13 C NMR / Solution 13 C NMR / Differential Scanning Calorimetry/ Mesophase Range/ Nematic Threaded-Schlieren Texture / Droplets Texture / Aromatic polyamides and polyesters have opened a new field of liquid-crystalline polymers with high strength and high modulus. 1 -3 In general, aromatic polyamides are of Iyotropic liquid crystalline, whereas aromatic polyesters are of thermotropic nature. Thermotropic polyamides fCOC6 H40(CH2)100-C6H4CONHC6HiX)C6HiX)NHf, prepared by polymerization of 4,4' -dichloroformyl-1, 10-diphenoxydecane and 3,3' -disubstituted-4,4' -diaminobiphenyl, have been reported. 4 Strictly speaking, these are poly(ether amides), though di-alkoxy portions in the poly(ether amides) are regarded as spacers to reduce transition temperatures. Synthesis of thermotropic liquid crystalline samples of wholly aromatic copoly(ester amides), in which p-aminophenol was used as an amino-containing component has been reported. 5 • 6 In the copoly(ester amide), however, the percentage of amide linkages included in all polymeric linkages was not so high. Recently, the synthesis of aliphatic-aromatic poly(ester amide) with thermotropic liquid crystalline character was reported. 7 * To whom correspondence should be addressed.Lenz and coworkers have synthesized various thermotropic polyesters with flexible spacers to lower the melting point. 8 Recently, we reported that solid-state 13 C NMR spectra of thermotropic polyesters with di-alkoxy spacers can provide exact information on their solid structures. 9 If di-alkoxy spacers are introduced in polymer backbone to lower the melting point and the liquid crystalinity measurement is carried out by use of both conventional polarizing 409 T. URYU, J. C. SONG, and T. KATO microscopy and solid-state 13 C N...

Liquid Crystalline Poly(ester amide)s Based on N,N‘-Dimethyldiamines and an Aromatic Ester Triad

“…Few amide-containing thermotropic liquid crystalline polymers, TLCPs, have been synthesized to date, − so this study was directed at preparing amide-containing TLCPs capable of forming compatible blends with nylons. Blends containing both amorphous or semicrystalline polyamides have been shown to be immiscible with the TLCPs presently available, such as Hoechst-Celanese's Vectra. − Miscibility of such blends of TLCPs is not anticipated because of the inherent tendency of rigid-rod polymers to self-associate, which makes the entropic energy of the blend even more unfavorable.…”

Thermotropic Liquid-Crystalline Copoly(ester amide)s and Copolyamides Containing a Flexible Spacer in the Main Chain

“…These compounds were synthesized by the methods reported in the Iiterature. 13 4 ,4 '-Diacetoamido-3 ,3 '-dichlorobiphenyl. 4,4' -Diamino-3,3'-dichlorobiphenyl (Tokyo Kasei Co.) (mp 132-133°C) (25g, 9.9x 10-2 mo!)…”

“…In the previous paper, 13 we investigated the relationship between structure and thermotropic behavior for four series of copoly(ester amide)s obtained by melt polymerization, and we found that solid-state and solution 13 C NMR spectra of thermotropic copoly(ester amide )s with dialkoxy spacers can provide exact information on their solid-state structures.…”

Synthesis and characterization of new thermally stable aromatic copoly(ester–amide)s from diester‐dicarboxylic acids

“…PEAs can be synthesized as random copolymers,5–7 alternating copolymers8–10 and block copolymers 11, 12. They can be prepared by ester exchange of the corresponding acetate,13–15 using a silyl acetate method13 and also from amido diols 4, 16, 17…”