A new diamine containing one keto and four ether groups was prepared through a three-step reaction: first, hydroquinone was reacted with 1-fluoro-4-nitrobenzene and 4-(4-nitrophenoxy) phenol was obtained. The next step was reduction of nitro group to amino group in which 4-(4-aminophenoxy) phenol was prepared. In the final step, the new diamine named as bis(4-(4-(4-aminophenoxy)phenoxy)phenyl) methanone was synthesized through reaction of the later compound with 4,4′-difluoro benzophenone. All prepared materials were fully characterized by spectroscopic methods and elemental analysis. Novel species of poly(keto ether ether amide)s were synthesized via polymerization reaction of the diamine with different diacid chlorides including terephthaloyl chloride, isophthaloyl chloride, and adipoyl chloride. All polyamides were characterized, and their properties such as thermal behavior, thermal stability, solubility, viscosity, water uptake, and crystallinity were investigated and compared together. The glass transition temperatures of the polymers were about 204-232°C, and their 10% weight losses were in the range of 396-448°C. Polymers showed high thermal stability and enhanced solubility that mainly resulted from incorporation of the diamine structure containing keto, ether, and aromatic units into polyamide backbones.
Reactions of 3-aminophenol with dichlorodiphenylsilane in the presence of triethylamine resulted in the preparation of a diamine named as bis(m-aminophenoxy)diphenylsilane. Reaction of the diamine with two moles of trimellitic anhydride led to the preparation of a diacid with preformed imide structures. Silicon-containing poly(amide-imide)s were then prepared by polycondensation reactions of the diacid with different diamines in the presence of triphenyl phosphite. All the products and polymers were characterized and the physical properties of the polymers including solubility, solution viscosity, thermal stability, thermal behavior, flameretardency, crystallinity, and morphology were studied. The polymers showed high thermal stability and flameretardency, as well as enhanced solubility in polar solvents. The glass transition temperature of the polymers was about 187-196°C, the temperature for 10% gravimetric loss was in the range of 375-400°C, and also the weight of the polymer remaining at 700°C was about 39-44%. They were flame-retardant, soluble in dipolar aprotic solvents, and showed some crystalline structures.
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