Fabrication and mechanical, electrical properties study of isocyanate-based polyimide films modified by reduced graphene oxide

Abstract

To synchronously improve mechanical properties and electrical conductivity of polyimide (PI) films, PI films with excellent mechanical, electrical conductivity, and antistatic properties that modified by reduced graphene oxide (rGO) were prepared by in-situ polymerization. Depending on the reaction between isocyanate groups and hydroxyl groups on rGO sheets, effectively chemical bonding between rGO and PI matrix was accomplished. They realized excellent compatibility and homogeneous dispersion in PI films and provided strong interfacial interaction with the PI matrix. Testing results revealed that with increasing rGO dosage, more and more ▪ groups formed between rGO and PI matrix. At the 0.7 wt% of rGO dosage, tensile strength and elastic modulus of the films increased to a maximum of 103.12 MPa and 3.90 GPa, respectively. Compared with pure PI films synthesized by anhydride and isocyanate, they enhanced about 74 % and 65 %, respectively. Moreover, surface and volume resistivity of films decreased with increasing rGO dosage. The surface resistivity of the films could reduce to 1.232×107 Ω with rGO dosage justly 1.0 wt%. It enhanced approximately nine orders of magnitude compared with pure PI films and met the standard for antistatic film material. Dielectric constant at 100 Hz reached to 4.808 (about 85 % increase compared with pure PI films). These results indicated that mechanical properties and electrical conductivity of PI films realized improvement synchronously by the incorporation of rGO. This invention will further promote the widespread application of PI films in electronic packaging fields. [Display omitted]