The Study Of Polyimide Containing The Siloxane-functionalized Graphene Oxide For Reinforcing

Polyimide(PI) is a kind of the polymers which have imide rings in their molecular chains. PI was widely applied to aerospace engineering, non-linear optical devices, light-wave guide materials and liquid crystal displays as well as in the electronics industry for packaging devices because of its excellent thermal properties, excellent mechanical properties, high chemical resistance, low dielectric constant and good radiation-proof properties. However, PI has strong rigidity and poor processability to eventually confine in the further application of high-performance area because of its backbones containing the benzene rings and imide rings. With the development of science and technology, the single-functional materials had been unable to meet the demands of high-performance area. So, the complex of multi-functional materials was obtained by using molecular design and molecular engineering, achieving the complementarity and optimization of material properties. In recent years, composite materials have become a hot topic and new growth point in the field of materials science due to the excellent physical and chemical characteristics of graphene oxide(GO). This also provides a new opportunity to prepare the high performance PI materials.The main research content and conclusions are as follows:(1) In this paper, GO was prepared by the Hummers’ method and the ultrasonic exfoliation process. The analysis results suggested that the thickness of GO was 0.822 nm. Moreover, the surface of GO had abundant oxygen-containing functional groups which were helpful to react with the amino of flexible diamine containing siloxane(DSX), the siloxane-functionalized GO(DSX-GO) was obtained eventually. The analysis results suggested that DSX-GO had good dispersibility and thermo stability.(2) The PI/GO composite films with various contents of GO were prepared via in situ polymerization process. The structure of PI matrix was not destroyed by the incorporation of GO through the analysis results of FT-IR and SEM characterization. And, the results of TGA and tensile test further demonstrated that the thermal stability and mechanical properties of the PI/GO composite films were improved to some extent with the increasing contents of GO. Moreover, the dielectric constants of the PI/GO composite films were lower than that of neat PI films with the increasing contents of GO. However, GO would be aggregated in the PI matrix to weaken the interaction between GO and PI due to the abundant oxygen-containing functional groups at the surface of GO.(3) On the basis of the above study, GO was functionalized by DSX, and then the interaction between GO and PI was increased through DSX-GO. And the results suggested that the properties of PI/DSX-GO composite films were obviously improved with the increasing contents of DSX-GO compared to the properties of PI/GO composite films. Moreover, the results also showed that the thermal decomposition temperature of PI/DSX-GO composite films was up to 510 °C, and the tensile modulus and tensile strength of the composite films increased to 20.08 GPa and 321.74 MPa, respectively.