Dielectric modeling of polyimide exposed to environmental stress

Wu, Shiann-Long; Denton, Denice D.

doi:10.1109/14.135607

Cited by 13 publications

(6 citation statements)

References 38 publications

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“…The reason for the PI film sensitive to the moisture is due to its internal chemical structure. ,, The water absorbed by the PI film can cause a hydrolysis effect, inducing the breaking of the carbon–nitrogen bonds. In the meanwhile, hydrogen bonds between the water molecule and the four carbonyl groups on the imide ring can be formed at low humidity, and the interchain hydrogen bonds between the water molecule and oxygen on the ether bond can be formed as well at high humidity, as shown in Figure a.…”

Section: Resultsmentioning

confidence: 99%

Surface Engineering on Polyimide–Silver Films in Low-Cost, Flexible Humidity Sensors

Luo

Liu

Wang

et al. 2022

ACS Appl. Mater. Interfaces

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In this work, surface engineering is applied to polyimide (PI) films to fabricate low-cost Ag/PI wireless humidity sensors with a resonant frequency of 2.45 GHz. The sensors were obtained by in situ metallization technique coupled with inkjet printing, where PI plays triple roles as a flexible substrate, ion-exchange surface, and sensing material to moisture. Moreover, the humidity sensitivity can be enhanced by the improvement of hydrophilicity via loading with different ions on the PI surface, which has been demonstrated by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The wireless humidity sensor loaded with K+ ions has the maximum sensitivity of 97.7 kHz/% RH at a low relative humidity range of 20–65% and 359.7 kHz/% RH at a high relative humidity of 65–90%, respectively. Accordingly, a sensing mechanism of the fabricated humidity sensor has been discussed in detail. On the other hand, the characteristics of the humidity sensor such as response and recovery speed and stability are analyzed. The mechanical performance tests show that the humidity sensor displays excellent flexibility and good mechanical stability. A strong adhesion between the Ag antenna and PI substrate can be found as well. The passive wireless humidity sensor described in this work has the advantages of having a simple structure, low cost, high sensitivity, long-term stability, and good mechanical properties, which has potential applications in automated industry and healthcare with real-time humidity monitoring.

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Section: Resultsmentioning

confidence: 99%

Surface Engineering on Polyimide–Silver Films in Low-Cost, Flexible Humidity Sensors

Luo

Liu

Wang

et al. 2022

ACS Appl. Mater. Interfaces

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“…Denton et al investigated the effect of high temperature and high humidity on the complex dielectric constant of PMDA-ODA polyimide (PI). 27 At frequencies less than 10 kHz, the dissipation factor remained almost constant, while above 10 kHz, the dissipation factor increased with increasing relative humidity, but the increase was not significant. The Ye group enhanced the hydrophilicity by loading different ions on the PI surface and obtained the relationship between the dielectric constant of PI and environmental humidity, thus preparing a low-cost Ag/PI wireless humidity sensor.…”

Section: ■ Introductionmentioning

confidence: 91%

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

Bei,

Chen,

Liu

et al. 2024

Macromolecules

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The development of polyimide (PI) films with both a low dielectric constant and low dissipation factor at high frequency is an urgent requirement in a new generation of mobile communication technology. Although some breakthroughs have been made in the study of low-dielectric constant polyimide, the main influencing factors and regulation of the high-frequency dissipation factors are still unclear, which severely limits its development and application, and they deserve further study. In this work, we prepared a series of low-dielectric constant polyimide films and measured their high-frequency dielectric properties at different humidity levels by using a homemade system. The free volume and water adsorption of these polyimide films were precisely evaluated by positron annihilation lifetime spectroscopy and the dynamic vapor sorption method, respectively. Our study shows that the main factor affecting the high-frequency dissipation factor of low-dielectric constant PI films is the water adsorption, and the influence of water adsorption capacity and water binding intensity on the increase of the high-frequency dissipation factor is analyzed in detail. The main factors affecting the water adsorption of these polyimide films are the free volume, molecular polarity index (MPI), and morphology. In the case of a similar structure, imide ring density, and morphology, the free volume of DP-BPDA, MDA-BPDA, TPM-BPDA, and FDA-BPDA gradually increases, resulting in an increase in water adsorption and high-frequency dissipation factors. HMDA-BPDA achieves a low water adsorption of 0.44% due to its appropriate free volume, low MPI, and partial crystallinity, thus achieving good comprehensive performance: low dielectric constant (2.84) and low dissipation factor (0.0029) at 50% RH. Therefore, for polymer materials, designing structures with low polarization, appropriate free volume, and low water adsorption will be an effective strategy to achieve both a low dielectric constant and low dissipation factor.

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“…Polyimide (PI) is an aromatic heterocyclic polymer with excellent mechanical properties, chemical stability, thermal stability, and radiation resistance. − It is widely used in spacecraft insulation, solar panel substrates, and circuit protection layers. , Moreover, due to its low dielectric constant, PI can also serve as a dielectric material for high-energy devices. , Extreme space environments in low Earth orbit (LEO), including atomic oxygen (AO), ultraviolet (UV), ultrahigh vacuum (UHV), thermal cycling, and orbital debris, − can significantly impact spacecraft exposed to these conditions for prolonged periods, which can shorten their service life. Among the various space environmental hazards, AO constitutes up to 80% of the LEO environment and represents the most critical environmental factor that leads to spacecraft failure; − its impact on PI substrates can cause severe erosion .…”

Section: Introductionmentioning

confidence: 99%

Reactive Molecular Dynamics Study of the Mechanism and Effect of Various Protective Coatings on the Protection of Polyimide Antierosion from Atomic Oxygen

Wei,

Zeng,

Cui

2024

J. Phys. Chem. A

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Polyimide (PI), due to its exceptional performance, is commonly utilized in spacecraft. However, when such polymers are used in spacecraft navigating low Earth orbit, they are exposed to atomic oxygen (AO) that can cause the polymer to decompose. A protective coating method is a more effective way to safeguard the polymer from erosion caused by AO. This study employs the molecular dynamics simulation based on the reaction force field to investigate the protective effects of various coatings, including polydimethylsiloxane (PDMS), graphene (Gr), polytetrafluoroethylene (PTFE), and the (0 0 1), (0 1 1), and (1 1 1) surfaces of SiO 2 . The results indicate that the protective performance of the (0 1 1) surface is superior to that of the (0 0 1) and (1 1 1) surfaces. Moreover, protective coatings are classified into three categories based on different protective mechanisms: rebound, absorption, and sacrificial. The protective effectiveness of coatings depends on their anti-AO performance and ability to combine with the substrate. Gr displays exceptional anti-AO properties and can effectively shield the substrate from AO erosion. Silicone-based coatings have a superior ability to adhere to PI substrates, and PDMS is an excellent choice for protective coatings. This paper offers guidance for the protective coating method of PIs against AO erosion.

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Dielectric modeling of polyimide exposed to environmental stress

Cited by 13 publications

References 38 publications

Surface Engineering on Polyimide–Silver Films in Low-Cost, Flexible Humidity Sensors

Surface Engineering on Polyimide–Silver Films in Low-Cost, Flexible Humidity Sensors

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

Reactive Molecular Dynamics Study of the Mechanism and Effect of Various Protective Coatings on the Protection of Polyimide Antierosion from Atomic Oxygen

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