Transparent Polyimide Film with Improved Water and Oxygen Barrier Property by In‐Situ Exfoliating Graphite

Abstract

A facile process is demonstrated to fabricate flexible and transparent polyimide (PI) thin films with improved moisture and oxygen barrier property by in situ solution-blending PI monomers with ultrasonicated graphite sheets in the solvent during imidization process. When the concentration of graphite in solvent is less than 0.3 wt%, graphite can be exfoliated to a thickness of less than 800 nm and homogeneously distributed in the precursor of PI solution. The resultant PI composite films containing exfoliated graphite (xG) show excellent transparency, enhanced mechanical strength, improved thermal stability and sufficient electrical insulation. Most importantly, the barrier property of PI/xG composite film is significantly improved by the distributed xG sheets in PI matrix. With the addition of 0.06 wt% of xG in PI matrix, the PI/xG-0.06 film show an oxygen-transmissionrate (OTR) of 152 cc/m 2 -day compared to 301 cc/m 2 -day for pure PI. The reduction degree in watervapor-transmission-rate (WVTR) by xG is higher than that in OTR. The WVTR of PI/xG-0.06 is 28 g/m 2 -day, which is only 17% of the value of pure PI. Those PI/xG thin films show the potential as substrate materials for modern flexible electronic devices.

Polyimide nanohybrid films with electrochemically functionalized graphene

“…With increasing EFG, the optical transmittance of the nanohybrid films decreased. In contrast, the nanohybrid film containing 0.1 wt% EFG still retained 80% transmittance at 550 nm, which is in the acceptable range for display substrates . Therefore, the nanohybrid films obtained may be used as transparent film materials for flexible display substrates.…”

Solubilization and Dispersion of Carbon Allotropes in Water and Non-aqueous Solvents

“…There are several reports on the solubilization of graphite and oxidized graphite (graphite oxide, GrO), − resulting mainly in graphene. In the dispersed state, the resulting carbon mainly appears in these processes in the form of graphite flakes with distinct sizes or, more frequently, graphene.…”

Polyimide/Graphene Nanocomposites with Improved Gas Barrier and Thermal Properties due to a “Dual‐Plane” Structure Effect

“…Additionally, it is difficult for the nanosheets to achieve a high orientation in the matrix, which is required for a remarkable improvement in the barrier properties. Currently, investigations on the barrier properties of pristine graphene‐filled PI composites have rarely been reported in the literature . Coleman and co‐workers developed a facile method to produce pristine graphene monolayers by solution‐phase exfoliation of graphite in certain organic solvents .…”