Overall Improvement in Dielectric, Water Resistance and Mechanical Properties of Polyimide Film via Synergy between GO and Sandwich‐type Porous Structure

Abstract

Simultaneous improvement in dielectric, water resistance and mechanical properties of polyimide (PI) films is critical for their practical use, but difficult to achieve. Herein, a sandwich‐type porous GO/PI film with excellent comprehensive properties was obtained through integrating a GO‐containing complex, fluorine‐containing porous structure and sandwich‐type distribution of porous structure by a simple, low‐cost and green breath figure method. With the addition of only a small amount of GO‐containing complex, a low dielectric constant of 2.21, water absorption of 0.51%, increment in dielectric constant after moisture treatment of 1.60% and high tensile strength of 113.1 MPa, tensile modulus of 1.70 GPa, with 35.39%, 79.42%, 81.81% of reduction and 17.22%, 21.43% of increase compared to PI film were shown, respectively. Moreover, these properties could be adjusted through regulating the component and porous structure by changing the parameters of breath figure method. These outstanding properties make the film a promising candidate for high‐performance low‐dielectric materials.

Effect of Water Absorption on Electric Properties of Temperature-Resistant Polymers

“…At the equilibrium, the absorption ratios for PMDA–ODA and BPDA–PDA were 2.7% and 2.5%, respectively. These values were in good agreement with the literature value of PMDA–ODA (=2.51%) [ 11 ]. The relatively high water absorption of PIs is due to the hydrogen bonding of the BI (benzimidazole imide) ring.…”

“…The dielectric constants for dried films of PMDA–ODA, BPDA–PDA, and PET were 3.2, 3.0, and 3.3, respectively. These values were in good agreement with the literature values of 2.94 for PI [ 14 ], 2.9–3.9 for PMDA–ODA [ 11 , 12 , 13 , 26 ], 3.1 for BPDA–PDA [ 12 ], and 3.4 for PET [ 49 ]. The dielectric constants for PMDA–ODA and BPDA–PDA increased with the absorption time and became constant at around 180 min.…”

“…Aromatic polyimides also have a great advantage in electrical insulating properties, as well as epoxy resin [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. That is, aromatic polyimides are electric insulators that can be used at high temperatures.…”

“…Generally, not only polyimides but also most polymers absorb moisture from the atmosphere, and their water absorbency depends on the chemical structure of the polymer. For example, the water absorption of the aromatic polyimides mentioned above is relatively high at 2.51% [ 11 ], and other examples are 10% for polybenzimidazole [ 21 ], 3.4% for CYCOM 977-2 epoxy resin [ 22 ], and 1.91% for 2,2-bis(4-cyanatophenyl)propane [ 23 ]. Conversely, the water absorptions of poly(ethylene terephthalate) and poly(phenylene sulfide) are relatively low at 1.1% [ 24 ] and 0.026% [ 25 ], respectively.…”

Research Advances of Porous Polyimide—Based Composites with Low Dielectric Constant

“…When the GO content was 0.5 wt.% and the UV irradiation time was 900 s, the dielectric constant and dielectric loss of the composite film reached the lowest, which were 2.58 and 0.026 at 10 MHz, respectively, due to the confined electronic polarization caused by the crosslinked structure. Han et al [ 59 ] fabricated a sandwich-type porous GO/PI film in which GO contained porous FPI film located on both sides of a flat PI film via a facile breath figure method using flat PI film and GO contained FPI organic solution as substrate and casting solution, respectively. The results showed that with the addition of 0.5 wt.% GO/dimethyldioctadecylammonium bromide (DODA), the lowest dielectric constant of 2.21 at 10 MHz was achieved.…”