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

Abstract

Graphene nanosheets are prepared by solution‐phase exfoliation of graphite and successfully incorporated with polyimide to obtain polyimide/graphene (DABPI/G) nanocomposites via in situ polymerization. Compared with those of pure DABPI, the DABPI/G nanocomposites exhibit better barrier and thermal properties. The oxygen and water vapor transmission rates of the DABPI/G (0.5 wt%) nanocomposite are 0.69 cm3 m−2 d−1 and 0.44 g m−2 d−1, respectively, which are 92 and 85% lower than those of pure DABPI. Meanwhile, the DABPI/G (0.5 wt%) nanocomposite exhibits excellent thermal stability with a Td5% of 578 °C and a coefficient of thermal expansion of −0.19 ppm K−1. The excellent barrier and thermal properties of DABPI/G nanocomposites are mainly attributed to the fine dispersion and orientation of the graphene nanosheets, increased crystallinity, and low free volume of the DABPI matrix. These are the result of the “dual‐plane” structure effect, which is the synergistic orientation effect between the rigid planar molecular chains of DABPI and the nanosheets of graphene.

Temperature Dependence of the Pore Structure in Polyvinylidene Fluoride (PVDF)/Graphene Composite Membrane Probed by Electrochemical Impedance Spectroscopy

“…For the PVDF/graphene membrane, there is no obvious change in the cross-section morphologies after being immersed in the water for 1 h at 50 °C. The existence of graphene sheets in the matrix can enhance the thermal stability of the composites, which has been confirmed by many research studies [22,23]. Thus, the thermal stability of the pore structure in the composite membrane should be attributed to the graphene introduced in the membrane.…”

Construction of lamellar morphology by side‐chain crystalline comb‐like polymers for gas barrier

“…After the reaction solution was cooled to room temperature, the unreacted TDA (or ODA) was precipitated and then removed. Finally, the reaction solution was poured into water, and then the precipitated product was collected and dried under vacuum at 70 C. The products were named as P(S-AA) n -g (14) and P(S-AA) n -g (18), respectively.…”

“…For example, the value of P(S-AA) 30 -g( 14) was 20.1%, while that of P(S-AA) 70 -g(18) corresponded to 52.6%. It could be noted that there was a burst increase of relative crystallinity upon increasing [AA] from 30 to 40 in the P(S-AA) n -g (18) series and from 40 to 50 in the P(S-AA) n -g( 14 F I G U R E 3 FTIR spectra of P(S-AA) 30 -g(14) (A) and P(S-AA) 30 -g (18) (B). FTIR, Fourier transform infrared closely packed side chain, which could facilitate a high degree of crystallinity.…”

“…nanosheets. [16][17][18][19][20] Frounchi 19 demonstrated the improvement of oxygen and carbon dioxide barrier property of PP/EPDM blend by adding only 1.5 vol% organoclay. Huang 20 prepared poly(lactic acid) (PLA) with randomly dispersed graphene oxide (GO) nanosheets, and a large decline in gas permeability coefficients of PLA films was obtained.…”

Nanoscale Mechanical Properties and Indentation Recovery of PI@GO Composites Measured Using AFM

“…Nowadays, electronic products require the PI to possess a high glass transition temperature and better thermal mechanical strength. To address this concern, PI-based composites with various fillers including carbon nanotubes [3], SiC, graphene [4], graphene oxide [5], SiO 2 [6], and aramid fibers [7] have been explored. The composites are highly affected by the reinforcements, in which the dimension, dispersion state, and the interaction of the reinforcements play significant roles.…”