Colorless PI structure design and evaluation for achieving low CTE target

Yu, Xiaohui; Liu, Jian‐Ni; Wu, Dayong

doi:10.1016/j.mtcomm.2019.100562

Cited by 30 publications

(20 citation statements)

References 28 publications

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“…PIs with higher packing densities generally possess higher T g s. [86][87][88] However, the motion of molecular chains promotes the disorder of their arrangement, resulting in higher CTE. [89][90][91]…”

Section: Two-step Methodsmentioning

confidence: 99%

“…87 The decrease of packing density helps improve PI film transmittance. 89,91 Additionally, the unstable terminal amino group will be closed by acetic anhydride in the process of chemical imidization, so that it avoids color change at high temperature due to oxidation. This is another reason why chemical imidization has high optical transmittance.…”

Section: Chemical Imidizationmentioning

confidence: 99%

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Synthetic strategies for highly transparent and colorless polyimide film

Liu

Wang

2022

J of Applied Polymer Sci

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Polyimide (PI) is one of the best engineering plastics with excellent thermal, mechanical, dielectric performance and chemical stability. Among various PI products, film is one of the most dominant types. If PI films are to be applied to optical devices and display equipment, it is necessary to improve their optical transparency in the ultraviolet–visible region. However, improving the optical transparency of PI films would affect their thermal performance including thermal and dimensional stability. Therefore, how to balance optical and thermal performance to obtain highly transparent PI films with the best overall performance becomes a focus of current research field. In this review, we categorize transparent PI films into highly transparent PI, transparent PI with high glass transition temperature (Tg) and transparent PI with low coefficient of thermal expansion (CTE) based on their optical and thermal properties. Then, we review research progress in the field of polymer molecular design including synthesis strategies and properties in recent 5 years, to inspire research ideas and elaborate on the possible ways to develop high‐performance, colorless and transparent PI materials.

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Section: Two-step Methodsmentioning

confidence: 99%

Section: Chemical Imidizationmentioning

confidence: 99%

Synthetic strategies for highly transparent and colorless polyimide film

Liu

Wang

2022

J of Applied Polymer Sci

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“…Nevertheless, the CPI-a film showed apparently reduced CTE value than that of the commercially available CPI film based on HPMDA, such as Neopulim ® L-3430 (CTE = 58.0 Â 10 À6 /K). 26 The low-CTE feature of CPI-a film is quite beneficial for the further decreasing the CTE value of the film via incorporation of inorganic nano-fillers. Small quantity of nano-fillers might be needed to achieve the lower CTE of the composite films.…”

Section: Thermal Propertiesmentioning

confidence: 99%

“…25 Generally, the high CTE features of the common semi-alicyclic CPI films, such as the one derived from hydrogenated pyromellitic dianhydride (HPMDA) and 4,4 0oxydianiline (ODA) (commercially available with the tradename of Neopulim ® by Mitsubishi Gas Chemical, Japan), is mainly due to the easy movement of the alicyclic chain segments in the dianhydride units at elevated temperatures. 26 Thus, most of the modifications for developing semi-alicyclic PI films with intrinsically low CTE values have been focused on development of functional diamine monomers containing rigid units, such as amide, ester, benzimidazole, benzoxazole, and so on. Among the various rigid-rod groups, amide ( CONH ) or benzanilide ( Ph CONH Ph ) linkages show the best effects for reducing the CTE values of the CPI films while maintaining the intrinsic thermal, tensile, and optical properties.…”

mentioning

confidence: 99%

Preparation and properties of colorless and transparent semi‐alicyclic polyimide films with enhanced high‐temperature dimensional stability via incorporation of alkyl‐substituted benzanilide units

Zhi

Jiang

Zhang

et al. 2021

J of Applied Polymer Sci

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Two colorless and transparent polyimide (CPI) films with enhanced high‐temperature dimensional stability and solution‐processability were prepared from the methyl‐substituted benzanilide containing organo‐soluble polyimide (PI) resins. For this target, a new aromatic diamine, 2,3′‐dimethyl‐4,4′‐diaminobenzanilide (MMDABA) was synthesized. The methyl substituents were expected to endow the derived PI resins good solubility and rigid‐rod benzanilide units can efficiently reduce the coefficients of thermal expansion (CTE) of the derived CPI films. CPI‐a and CPI‐b were prepared by the one‐step thermal polycondensation from MMDABA with hydrogenated pyromellitic dianhydride for CPI‐a and hydrogenated 3,3′,4,4′‐biphenyltetracarboxylic dianhydride for CPI‐b, respectively. The derived PI resins were soluble in polar aprotic solvents. Colorless and transparent CPI‐a and CPI‐b films were prepared from the PI solutions and the subsequent 280°C curing. The CPI films showed good transparency in visible light and transmittances higher than 80% at 450 nm and yellowness index (b*) below 2.0. More importantly, the derived CPI‐a film showed the glass transition temperature (Tg) of 417.5°C and the CTE value of 46.9 × 10−6/K in the range of 50–250°C. Apparently, incorporation of alkyl‐substituted benzanilide units achieved good balance among solution‐processability, high‐temperature dimensional stability, and optical properties.

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“…In order to obtain transparent or even colorless PIs, various effective strategies have been reported to suppress or eliminate the charge transfer interactions. Researchers, respectively, introduce bulky pendant substituents, flexible linkages, noncoplanar or asymmetric units, non-aromatic structures or electron-withdrawing functional groups into polymer backbone [ 18 , 19 , 20 , 21 ]. Among these strategies, the adoption of alicyclic dianhydrides with weak electron-accepting abilities or alicyclic/aliphatic diamines with weak electron-donating abilities can effectively suppress the formation of CTC.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Characterization of Semi-Alicyclic Polyimides Containing Trifluoromethyl Groups for Optoelectronic Application

et al. 2020

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Transparent polyimides (PI) films with outstanding overall performance are attractive for next generation optoelectronic and microelectronic applications. Semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines have proved effective to prepare transparent PIs with high transmittance. To optimize the combined properties of semi-alicyclic PIs, incorporating bulky trifluoromethyl groups into the backbones is regarded as a powerful tool. However, the lack of fundamental understanding of structure–property relationships of fluorinated semi-alicyclic PIs constrains the design and engineering of advanced films for such challenging applications. Herein, a series of semi-alicyclic PIs derived from alicyclic dianhydrides and trifluoromethyl-containing aromatic diamines was synthesized by solution polycondensation at high temperature. The effects of alicyclic structures and bulky trifluoromethyl groups on thermal, dielectric and optical properties of PIs were investigated systematically. These PI films had excellent solubility, low water absorption and good mechanical property. They showed high heat resistance with Tg in the range of 294–390 °C. It is noted that tensile strength and thermal stability were greatly affected by the rigid linkages and alicyclic moieties, respectively. These films exhibited obviously low refractive indices and significantly reduced dielectric constants from 2.61 to 2.76, together with low optical birefringence and dielectric anisotropy. Highly transparent films exhibited cutoff wavelength even as low as 298 nm and transmittance at 500 nm over 85%, displaying almost colorless appearance with yellowness index (b*) below 4.2. The remarkable optical improvement should be mainly ascribed to both weak electron-accepting alicyclic units and bulky electron-withdrawing trifluoromethyl or sulfone groups. The present work provides an effective strategy to design molecular structures of optically transparent PIs for a trade-off between solution-processability, low water uptake, good toughness, high heat resistance, low dielectric constant and excellent optical transparency.

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Colorless PI structure design and evaluation for achieving low CTE target

Cited by 30 publications

References 28 publications

Synthetic strategies for highly transparent and colorless polyimide film

Synthetic strategies for highly transparent and colorless polyimide film

Preparation and properties of colorless and transparent semi‐alicyclic polyimide films with enhanced high‐temperature dimensional stability via incorporation of alkyl‐substituted benzanilide units

Preparation and Characterization of Semi-Alicyclic Polyimides Containing Trifluoromethyl Groups for Optoelectronic Application

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