Dielectric and mechanical properties and thermal stability of polyimide–graphene oxide composite films

• Polyimide/graphene oxide films were prepared by in-situ polymerization process.
• Performance of composites was effectively enhanced even at a low content.
• Interfacial polarization relaxation has a major influence on the dielectric properties.

Graphene oxide (GO) was incorporated into polyimide (PI) resin to obtain composite films via in-situ polymerization method. The GO sheets were well dispersed in the PI matrix due to the hydrophilic nature of oxygen-containing groups in GO sheets. The resulting composite's mechanical, electrical and thermal properties are effectively enhanced by the incorporation of GO even at a low content. The effects of GO content on the dielectric permittivity, loss tangent and breakdown strength were simultaneously studied. The tensile strength of the PI composites was significantly increased by 40% for a 0.5 wt.% GO addition and the tensile elongation (32%) was three times greater than that of pure PI film. In addition, enhanced thermal stability was also achieved. Our composite design and fabrication methodology can be extended to many other polymer composites and thus provide a simple approach to reinforce the properties for polymer matrix in other applications.