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 the final polymer characteristics. In this way, nucleophilic substitution reaction of 4,4 -oxydianiline with 6-chloronicotinoyl chloride yielded a dichlorodiamide compound (DCDA) which by reaction with 5-amino-1-naphthol afforded a new diamine with specific structural features. Polycondensation reaction of the diamine with different aro- matic dianhydrides using a two-step method and in an ionic liquid of one step method resulted in formation of novel polyimides. All the precursors and polyimides were fully characterized using routine analytical methods and their physical and thermal properties including solution viscosity, thermal stability and behaviour, crystallinity and solubility were investigated. According to the obtained results polyimides showed high thermal stability and improved solubility. Using IL as a media in one step method for the preparation of polyimides led to improved properties in comparison to conventional two-step method of imidization. The inherent viscosity of the polymers was in the range of 0.40-0.88 dL/g for polyimides prepared via two-step method, and 0.52-0.93 dL/g for polyimides prepared via IL one-step method. The weight loss of 10% as an important criterion for evaluation of thermal stability occurred in the range 430-445°C for polyimides prepared by two-step method, while the same weight loss took place in the range 457-474°C for polyimides prepared by IL one-step method.