Synthesis Of Fluorine-containg Polyimide、Polyamide Intermediates

Fluorinated polyimide, polyamide are high performance engineering plastics and have been widely used in aerospace and electrical and electronic applications because of their outstanding thermal and mechanical, chemical properties. Research progress of polyimide and polyamide is introduced in this paper. At the same time, the development of polyimide and polyamide are also investigated. However, polyimide and polyamide are often limited for further application because of the insolubility in most organic solvents.To overcome the problem, more and more attempts have been focused on the preparation of novel polyimide and polyamide without sacrificing the thermal and mechanical properties. From the perspective of monomer, design and synthesis of a novel monomer with specific structure could improve the solubility of polymers. This paper is mainly composed of three parts as follows.Firstly, a series of new fluorinated aromatic diamine monomers were successfully synthesized using hydroquinone, hydroxyphenol, bisphenol A, bisphenol AF as starting matericals in the presence of potassium carbonate to yield corresponding dinitro compounds, and then reduce the dinitro compounds to the corresponding phenolic diamines with FeCl3·6H2O/C. The optimum reations condition of the first step was obtained as follows:the ratio of phenol and K2CO3and chloronitrobenzen is0.5:1.08:1.08, reaction temperature155-165℃, reaction time5h.The chemical structure of the intermediate dinitro compounds and diamines were identified by means of IR. The purity was tested by liquid chromatography As (CF3)2-and-O-units introduced into diamine molecules, they could be used to synthesize the corresponding polymers with good solubility. The flexible ether linkages and the nonplanar configuratio of hexafluoroisopropyl moiety are can destroy the regularity of the polymer chain, to reduce the intermolecular forces, thereby enhancing the solubility of the polyimide.A new new fluorinated aromatic diacid was synthesized—2,2-bis (4-carboxyphenyl) hexafluoropropane. The dicarboxylic acid was synthesized by the oxidation of2,2-bis (4-methylphenyl) hexafluoropropane with molecular oxygen. The oxidation was carried out in the presence of a new catalyst system consisting of N-hydroxyphthalimide (NHPI) and a small amount of Co(OAc)2with molecular oxygen. The chemical structure of2,2-bis (4-carboxyphenyl) hexafluoropropane was identified by means of IR, H-NMR, F-NMR. The influence of reaction temperature, reaction time, pressure, and the amount of catalyst NHPI on the oxidation have investigated. The optimum reations condition of the oxidation as follows: reaction temperature130℃, reaction time18h, O2pressure1.0MPa. The fact that the oxidation2,2-bis (4-carboxyphenyl) hexafluoropropane can be oxidized by oxygen under mild conditions is an important meaning for oxidation chemistry.A series of fluorine-containing polyimides were synthesized by6FDA and ethanediamine, butanediamine, hexamethylendiamine through the conventional two-step chemical imidization method. The polymer constructions were identified by means of IR. The solubility, thermal properties of the polyimides were investigated by means of TGA and DSC. The results showed that the polyimids have inherent viscosities of0.655～1.052dL/g and excellent solubility in strong polar solvents such as NMP and DMAc, excellent thermal stability, decomposition temperature in nitrogen atmosphere above505℃.