Studies of dielectric characteristics and surface energies of spin‐coated polyimide films

Qu, Wenli; Ko, Tze‐Man

doi:10.1002/app.2004.abs

Cited by 5 publications

(6 citation statements)

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“…Polyimide 3 has a glass transition temperature of 310 °C, which is similar to the T g of polyimide 2 . Polyimide 4 is synthesized from the monomers 6F‐DA and 2,2‐bis(4‐aminophenyl)hexafluoropropane in benzoic acid. The achieved inherent viscosity is 0.52 dL g −1 .…”

Section: Resultsmentioning

confidence: 99%

Fluorinated Aromatic Polyimides as High-Performance Electret Materials

Erhard

Richter

Bartz

et al. 2015

Macromol. Rapid Commun.

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In view of the increasing significance of technology-driven devices such as microelectromechanical systems, energy-harvesting devices, and organic field effect transistors, polymer electret materials with durable electret performance at elevated temperatures become more and more important. However, typical polymer electret materials lose their performance at elevated temperatures. To provide polymer materials with improved electret performance over a broad temperature range, a series of aromatic polyimides with different degree of fluorosubstitution is presented. Isothermal surface potential decay measurements at elevated temperatures reveal that minor differences in the chemical structure have a major influence on the electret behavior. The best performance is found for the polyimide containing a hexafluoroisopropylidene moiety in both the bisanhydride- and the diamine-based unit. Excellent long-term charge storage stability at 120 °C is observed. From the initial surface charge 94% remains after 24 h. This polyimide even tolerates short-term exposure of 30 s at 300 °C with almost no loss of performance. These findings demonstrate that this particular polyimide is suitable for device applications at elevated temperatures during fabrication and use.

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Section: Resultsmentioning

confidence: 99%

Fluorinated Aromatic Polyimides as High-Performance Electret Materials

Erhard

Richter

Bartz

et al. 2015

Macromol. Rapid Commun.

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“…The CTEs of the resulting PI films were detected through TMA measurement and the results are shown in Table . According to previous reports, the CTEs of PIs depended on their chain packing density and chain orientation . In other words, a PI has the low in‐plane chain orientation and the low chain packing density usually gives a high CTE.…”

Section: Resultsmentioning

confidence: 88%

Soluble and transparent polyimides with high T_g from a new diamine containing tert‐butyl and fluorene units

Lee

Huang

et al. 2015

J. Polym. Sci. Part A: Polym. Chem.

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A novel diamine monomer 1, 4,4'-(9H-fluorene-9,9-diyl)-bis(2-tert-butylaniline), was synthesized from 9-fluorenone and 2-tert-butylaniline by the condensation reaction. Then it was polymerized with several commercial aromatic dianhydrides, respectively, to produce polyimides (PIs) by the one-pot method. The number-averaged molecular weights of the resulting PIs are in the range of (4.54-8.82) 3 10 4 with polydispersity indices from 2.51 to 4.33 by gel permeation chromatography measurement. They are soluble in many organic solvents and can form transparent and tough films by solution-casting. The cut-off wavelengths of UV-vis absorption for the PI films are below 360 nm, which are much lower than that of Kapton film. The light transparency of them is above 90% in the visible light range from 400 to 760 nm. They also display relatively low dielectric constants (from 2.79 to 3.00), low water absorption rates (<1%), and high tensile strength (> 50 MPa). Their excellent solubility and transparency can be attributed to the incorporation of tert-butyl groups and fluorene units into the rigid backbones of PIs. Simultaneously, they still maintain the high thermal stability (the 5% weight loss temperature in the range from 526 to 539 8C in nitrogen) and the high glass transition temperatures (T g > 340 8C).

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“…Generally, PIs with linear/stiff backbones usually had low CTE values due to their large packing density 30,31. What's more, the level of in‐plane orientation of PI films played a more important part in dominating the low CTE than that of the backbone 32–34. However, the high molecular mobility usually caused orientational relaxation in annealing.…”

Section: Resultsmentioning

confidence: 99%

Optically Transparent and Thermal‐Stable Polyimide Films Derived from a Semi‐Aliphatic Diamine: Synthesis and Properties

Chen

et al. 2020

Macro Chemistry & Physics

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A novel semi‐aliphatic diamine with bulky cyclohexyl and ortho‐substituted tertiary butyl groups (4,4'‐(cyclohexylmethylene)bis(2‐(tert‐butyl)aniline), CHMBTBA) is synthesized via Mannich and rearrangement reactions of cyclohexanecarboxaldehyde and 2‐tert‐butylaniline. Afterward, several semi‐aliphatic polyimides are prepared by the high‐temperature one‐pot polymerization of CHMBTBA with various aromatic dianhydrides respectively. The resulting PIs exhibit outstanding solubility in common organic solvents (i.e., trichloromethane, etc.) and are easily processed into light color or colorless transparent films (thickness: 25 ± 1 µm) by the blade coating of polymer solution. The transmittance of all resulting films is above 86% in the visible light region (400–760 nm). Their glass transition temperatures exceed 310 °C and reach even to 374 °C (by differential scanning calorimetry). They also display low water absorption (0.29–0.87%) and good mechanical properties (tensile strength: 50.9–87.7 MPa, Young's modulus: 2.0‐2.5 GPa, elongation at break: 3.8–7.6%). Thus, they are promising potential candidates for flexible display substrates.

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Studies of dielectric characteristics and surface energies of spin‐coated polyimide films

Cited by 5 publications

References 0 publications

Fluorinated Aromatic Polyimides as High-Performance Electret Materials

Fluorinated Aromatic Polyimides as High-Performance Electret Materials

Soluble and transparent polyimides with high T_g from a new diamine containing tert‐butyl and fluorene units

Optically Transparent and Thermal‐Stable Polyimide Films Derived from a Semi‐Aliphatic Diamine: Synthesis and Properties

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Studies of dielectric characteristics and surface energies of spin‐coated polyimide films

Cited by 5 publications

References 0 publications

Fluorinated Aromatic Polyimides as High-Performance Electret Materials

Fluorinated Aromatic Polyimides as High-Performance Electret Materials

Soluble and transparent polyimides with high Tg from a new diamine containing tert‐butyl and fluorene units

Optically Transparent and Thermal‐Stable Polyimide Films Derived from a Semi‐Aliphatic Diamine: Synthesis and Properties

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Soluble and transparent polyimides with high T_g from a new diamine containing tert‐butyl and fluorene units