Novel self-dyed wholly aromatic polyamide-hydrazides covalently bonded with azo groups in their main chains: 1. Structure-property relationships.

Nadia A Mohamed, Mohammad H Sammour, Ali M Elshafai

Index: Molecules 17(12) , 13969-88, (2012)

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Abstract

Twelve novel intrinsically colored wholly aromatic azopolyamide-hydrazides containing various proportions of para- and meta-phenylene units were successfully synthesized by a low temperature (-10 °C) solution polycondensation reaction of either 4-amino-3-hydroxybenzhydrazide (4A3HBH) or 3-amino-4-hydroxybenzhydrazide (3A4HBH) with an equimolar amount of either 4,4'-azodibenzoyl chloride (4,4'ADBC), 3,3'-azodibenzoyl chloride (3,3'ADBC), or mixtures of various molar ratios of 4,4'ADBC and 3,3'ADBC in anhydrous N,N-dimethyl acetamide (DMAc) containing 3% (wt/v) LiCl as a solvent. The structures of the polymers were proven by elemental analysis, FTIR, ¹H- and ¹³C-NMR spectroscopy. The polymers’ properties were strongly affected by their various structures. The intrinsic viscosities of the polymers were ranged from 0.7 to 4.75 dL g⁻¹ and increased with the para-phenylene units content. The polymers are partially soluble in DMAc, dimethyl formamide (DMF) and N-methyl-2-pyrrolidone (NMP). Their solubility increases with the introduction of meta-phenylene moieties into the polymer chains. The polymers exhibit a great affinity for water sorption. Their hydrophilicity increases as a function of the content of meta-phenylene rings incorporated into the polymer. Mechanical properties of the polymer films are improved markedly by substitution of para-phenylene units for meta-phenylene units. The completely para-oriented type polymer has the best thermal and thermo-oxidative stability relative to those of the other polymers.