Soluble and Thermally Stable New Pyridine-based Poly(Ether Imide)s Synthesized Through Conventional and Ionic Liquid Methods

Novel types of polyimides with specific properties were prepared by two ways,namely the conventional two-step and ionic liquid methods (IL) to compare thefinal polymer characteristics. In this way, nucleophilic substitution reaction of4,4'-oxydianiline with 6-chloronicotinoyl chloride yielded a dichlorodiamide compound(DCDA) which by reaction with 5-amino-1-naphthol afforded a new diamine withspecific structural features. Polycondensation reaction of the diamine with different aromaticdianhydrides using a two-step method and in an ionic liquid of one step methodresulted in formation of novel polyimides. All the precursors and polyimides were fullycharacterized using routine analytical methods and their physical and thermalproperties including solution viscosity, thermal stability and behaviour, crystallinity andsolubility were investigated. According to the obtained results polyimides showed highthermal stability and improved solubility. Using IL as a media in one step method for thepreparation of polyimides led to improved properties in comparison to conventionaltwo-step method of imidization. The inherent viscosity of the polymers was in the rangeof 0.40-0.88 dL/g for polyimides prepared via two-step method, and 0.52-0.93 dL/g forpolyimides prepared via IL one-step method. The weight loss of 10% as an importantcriterion for evaluation of thermal stability occurred in the range 430-445°C forpolyimides prepared by two-step method, while the same weight loss took place in therange 457-474°C for polyimides prepared by IL one-step method.