Abstract
The developing flexible electronic equipment are greatly affected by the rapid accumulation of heat, which is urgent to be solved by thermally conductive polymer composite films. However, the interfacial thermal resistance (ITR) and the phonon scattering at the interfaces are the main bottlenecks limiting the rapid and efficient improvement of thermal conductivity coefficients (λ) of the polymer composite films. Moreover, few researches were focused on characterizing ITR and phonon scattering in thermally conductive polymer composite films. In this paper, graphene oxide (GO) was aminated (NH2-GO) and reduced (NH2-rGO), then NH2-rGO/polyimide (NH2-rGO/PI) thermally conductive composite films were fabricated. Raman spectroscopy was utilized to innovatively characterize phonon scattering and ITR at the interfaces in NH2-rGO/PI thermally conductive composite films, revealing the interfacial thermal conduction mechanism, proving that the amination optimized the interfaces between NH2-rGO and PI, reduced phonon scattering and ITR, and ultimately improved the interfacial thermal conduction. The in-plane λ (λ||) and through-plane λ (λ⊥) of 15 wt% NH2-rGO/PI thermally conductive composite films at room temperature were, respectively, 7.13 W/mK and 0.74 W/mK, 8.2 times λ|| (0.87 W/mK) and 3.5 times λ⊥ (0.21 W/mK) of pure PI film, also significantly higher than λ|| (5.50 W/mK) and λ⊥ (0.62 W/mK) of 15 wt% rGO/PI thermally conductive composite films. Calculation based on the effective medium theory model proved that ITR was reduced via the amination of rGO. Infrared thermal imaging and finite element simulation showed that NH2-rGO/PI thermally conductive composite films obtained excellent heat dissipation and efficient thermal management capabilities on the light-emitting diodes bulbs, 5G high-power chips, and other electronic equipment, which are easy to generate heat severely.
Highlights
Flexible electronic equipment are developing rapidly in the directions of high-power, high-density, and highintegration with the advent of the 5G era [1, 2]
X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Raman, and atomic force microscope (AFM) proved that NH2rGO thermally conductive fillers with only a few layers were successfully prepared
Raman proved that the amination improved the interfaces between NH2-reduced graphene oxide (rGO) fillers and PI matrix and reduced the phonon scattering at the interfaces as well as the interfacial thermal resistance (ITR)
Summary
Flexible electronic equipment are developing rapidly in the directions of high-power, high-density, and highintegration with the advent of the 5G era [1, 2]. As far as we know, few researchers have utilized Raman spectroscopy to study the interfacial thermal conduction properties such as ITR and phonon scattering in thermally conductive polymer composite films. This paper is aimed at optimizing the interfaces between reduced graphene oxide (rGO) and PI, and Raman spectroscopy is innovatively performed to conduct the targeted and detailed investigation on phonon scattering and ITR in the thermally conductive PI-based composite films, revealing the interfacial thermal conduction mechanism. Raman spectroscopy was performed to characterize the phonon scattering and ITR at the interfaces in the NH2-rGO/PI thermally conductive composite films, revealing the thermal conduction mechanism at the interfaces On this basis, the influences of the amount of NH2-rGO thermally conductive fillers, ambient temperature and amination on the λ, and mechanical properties and thermal properties of the NH2rGO/PI thermally conductive composite films were analyzed and studied in detail
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