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Molecules 2012, 17(12), 13969-13988; doi:10.3390/molecules171213969
Article

Novel Self-Dyed Wholly Aromatic Polyamide-Hydrazides Covalently Bonded with Azo Groups in Their Main Chains: 1. Structure-Property Relationships

1,* , 2
 and
2
1 Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt 2 Excellence Center of Science and Technology, Elsalam-2, Cairo 3066, Egypt
* Author to whom correspondence should be addressed.
Received: 4 September 2012 / Revised: 2 November 2012 / Accepted: 12 November 2012 / Published: 26 November 2012
(This article belongs to the Section Organic Synthesis)
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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.
Keywords: azopolyamide-hydrazides; intrinsic viscosity; solubility; crystallinity; mechanical properties; thermal characteristics azopolyamide-hydrazides; intrinsic viscosity; solubility; crystallinity; mechanical properties; thermal characteristics
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Mohamed, N.A.; Sammour, M.H.; Elshafai, A.M. Novel Self-Dyed Wholly Aromatic Polyamide-Hydrazides Covalently Bonded with Azo Groups in Their Main Chains: 1. Structure-Property Relationships. Molecules 2012, 17, 13969-13988.

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