Study On Preparation And Properties Of Polyimide/Nano-mgO Composites

Polyimide(PI), as one kind of remarkably versatile polymer materials with excellent comprehensive performance, has attracted more and more attention and recognition. However, with the development of science and technology, the properties of single material can not satisfy the needs of human. So combining the functional inorganic nanomaterials with polyimide matrix and developing polyimide nanocomposites with high performance and multi-functionality is of great significance.The compatibility between inorganic particles and matrix materials is vital to polymer-based inorganic nanocomposites. Generally, a third component like coupling agent or surface modifier is introduced to enhance the compatibility between organic and inorganic phases and prevent phase separation. However, the addition of the third component has negative effect on the properties of the composites materials, such as optical, dielectric and thermal properties. Hence, the resolution of the compatibility of organic and inorganic phases without affecting the performances of the matrix is still a key topic for current research of the composite materials.In this paper, the methods of direct dispersion and in situ sol-gel polymerization were adopted to combine the nanometer Mg O into fluorinated polyimide. PI/Mg O composite films were prepared without any coupling agents or surface modifiers, which had good compatibility and excellent comprehensive properties. The compatibility was improved by taking advantage of the interaction between organic and inorganic components. Further more,a phosphine oxide structure was introduced into the polyimide molecule to enhance the interaction between the matrix and nano-Mg O. The structure, morphology and properties of the composites were characterized by the means of FTIR?XRD?SEM?UV–Vis?TGA and nano-scratch test, and the interaction mechanism of nanometer Mg O and polyimide was discussed. The main contents include the following aspects:Polyimide/nano-Mg O composites were prepared successfully by directly dispersing nano-Mg O particles into the polyamide acid solution followed by spin coating and thermal imidization. The results showed that nano-Mg O particles with average size of ca. 20 nm were well dispersed in the polyimide matrix, and the compatibility between the organic and inorganic components was good, which was benefitted from the coordination between the carboxyl group of polyamide acid and Mg atom; the as-prepared composite films exhibited excellent optical transparency in the visible region and good UV-shielding properties in the UV region. It was found that the anti-scratch properties of the composites were enhanced substantially with the addition of nano-Mg O. Under a scratching force of 100 ?N, the scratching depth dropped from 57.4 nm of pure PI to about 10 nm of PI/nano-Mg O composites, and the width of the scratches also decreased significantly. Although the thermal stability of the composites was slightly inferior to pure PI, they still possessed fairly good thermal stability under the temperature of 300 oC.A novel composite of polyimide/nano-Mg O was prepared by the self-made diamine monomer m DA6 FPPO containing phosphine oxide structure and 6FDA via an in situ sol–gel polymerization technique. Due to the introduction of phosphine oxide structure, the adhesion of polyimide to substrate was significantly improved, and the compatibility between polyimide and nano-Mg O was also enhanced because of the stable chemical bond formed between the P=O and nano-Mg O. In the PI/Mg O composite, nano-Mg O particles were uniformly dispersed in the polyimide matrix and no phase separation occurred. Test results indicated that the introduction of nano-Mg O leaded to the significantly improvement of the mechanical properties of the polyimide containing phosphine oxide structure, but the adhesive ability and heat resistance performance were declined. Composite with 1wt% nano-Mg O exhibited excellent adhesive ability and heat resistance performance, and has broad application prospects in the field of high temperature protection coatings.