Studies on reactions of the N‐phosphonium salts of pyridines. XIV. Wholly aromatic polyamides by the direct polycondensation reaction by using phosphites in the presence of metal salts

Abstract

Poly‐p‐benzamide of high molecular weight (ηinh = ∼ in H2SO4) was obtained by the direct polycondensation reaction of p‐aminobenzoic acid (p‐ABA) by means of diphenyl and triaryl phosphites in N‐methylpyrrolidone (NMP)‐pyridine solution containing lithium and calcium chlorides. Molecular weight of polymer varied with the amount of these salts, showing maximum values at the concentration of about 4 wt‐% of LiCl or about 8 wt‐% of CaCl2 in the reaction mixture. The reaction temperature at around 80°C gave a polymer of the highest viscosity. The polycondensation reaction was also affected by monomer concentration, solvents, and tertiary amines like pyridine. Similarly, aromatic polyamides with high molecular weight (ηinh values up to 1.34 in H2SO4) were prepared from isophthalic acid and aromatic diamines, whereas terephthalic acid gave only low‐viscosity polymers.

Direct condensation polymerization of N-alkylated p-aminobenzoic acid and packing of rigid-rod main chains with flexible side chains

“…The monomers were characterized by IR, NMR and elemental analyses. The polycondensation of p-aminobenzoic acid was performed using the method of Yamazaki et al, 34 involving a triphenyl phosphine oxide/pyridine/lithium chloride condensation agent system, to give the corresponding polymer (PABA 0 ) with an inherent viscosity of 1.18 per 100 ml g À1 (0.5 g per 100 ml in conc. H 2 SO 4 , 30 1C).…”

Relevance of purification procedures in the direct synthesis of poly(p-phenyleneterephthalamide) from its dimer

“…1 (entry 7) and compared to the only literature value previously reported for the same monomer by Preston et al [14] (entry 6), as well as to values typical of the corresponding commercial products (entry 1), and to data reported by Yamazaki et al [7], Higashi et al [8], Preston et al [9] and ourselves [13] using PPD and TA as reactants. Lately, we suggested that direct polyamidation of PPD and TA can lead to additional [η] enhancement, using the same experimental conditions as employed by Preston et al but paying special attention to the purification of all reaction components [10][11][12][13].…”

“…The first studies on the direct synthesis of aramids have been performed by Yamazaki et al [7] in the seventies. For PPDT, the reaction mixture was constituted of terephthalic acid (TA), PPD, NMP, pyridine (Py), LiCl (or CaCl 2 ) and TPP.…”

“…With the present work we planned to ascertain whether both the purification extent and the procedures employed could increase PPDT molecular weight also when APTA is used. [7] TA + PPD 0.2 3 PPDT (Higashi et al) [8] TA + PPD 4.5 4 PPDT (Preston et al) [9] TA + PPD 6.2 5 PPDT (previous work of ours) [13] TA + PPD 11.0 6 PPDT (Preston et al) [ …”

Silicon-Containing Poly(imide-Amides) Derived From Aliphatic Diacids With Naphathalimidyl Side Groups: Synthesis and Thermal Studies

“…Polymers were obtained by the Yamazaki procedure and were characterized by spectroscopic methods and the thermal properties were determined. 10 The results were related to the polymeric structure.…”