Highly transparent polyimide hybrids for optoelectronic applications

Tsai, Chia-Liang; Yen, Hung‐Ju; Liou, Guey‐Sheng

doi:10.1016/j.reactfunctpolym.2016.04.021

Cited by 129 publications

(81 citation statements)

References 242 publications

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“…The most reliable high-temperature polymeric materials for these applications are aromatic polyimides (PIs). That is to their excellent combined properties, including short-term heat resistance (glass transition temperature, Tg) and long-term heat resistance (thermal decomposition temperature, Td), flame retardancy, resistance to chemicals, mechanical properties, and dimensional stability against thermal cycles in the device fabrication processes [1][2][3][4][5][6][7][8][9][10]. One of the widest uses of PI products is, at present, their applications as dielectric substrates in flexible printed circuit boards (FPCs).…”

Section: Introductionmentioning

confidence: 99%

Poly(ester imide)s Possessing Low Coefficients of Thermal Expansion and Low Water Absorption (V). Effects of Ester-linked Diamines with Different Lengths and Substituents

Hasegawa

Hishiki

2020

Polymers

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A series of ester-linked diamines, with different lengths and substituents, was synthesized to obtain poly(ester imide)s (PEsIs) having improved properties. A substituent-free ester-linked diamine (AB-HQ) was poorly soluble in N-methyl-2-pyrrolidone at room temperature, which forced the need for polyaddition by adding tetracarboxylic dianhydride solid into a hot diamine solution. This procedure enabled the smooth progress of polymerization, however, accompanied by a significant decrease in the molecular weights of poly(amic acid)s (PAAs), particularly when using hydrolytically less stable pyromellitic dianhydride. On the other hand, the incorporation of various substituents (–CH3, –OCH3, and phenyl groups) to AB-HQ was highly effective in improving diamine solubility, which enabled the application of the simple polymerization process without the initial heating of the diamine solutions, and led to PAAs with sufficiently high molecular weights. The introduction of bulkier phenyl substituent tends to increase the coefficients of thermal expansion (CTE) of the PEsI films, in contrast to that of the small substituents (–CH3, –OCH3). The effects of ester-linked diamines, consisting of longitudinally further extended structures, were also investigated. However, this approach was unsuccessful due to the solubility problems of these diamines. Consequently, the CTE values of the PEsIs, obtained using longitudinally further extended diamines, were not as low as we had expected initially. The effects of substituent bulkiness on the target properties, and the dominant factors for water uptake (WA) and the coefficients of hygroscopic expansion (CHE), are also discussed in this study. The PEsI derived from methoxy-sustituted AB-HQ analog and 3,3′,4,4′-biphenyltetracarboxylic dianhydride achieved well-balanced properties, i.e., a very high Tg (424 °C), a very low CTE (5.6 ppm K−1), a low WA (0.41%), a very low CHE value (3.1 ppm/RH%), and sufficient ductility, although the 26 μm-thick film narrowly missed certification of the V-0 standard in the UL-94V test. This PEsI film also displayed a moderate εr (3.18) and a low tan δ (3.14 × 10−3) at 10 GHz under 50% RH and at 23 °C. Thus, this PEsI system is a promising candidate as a novel dielectric substrate material for use in the next generation of high-performance flexible printed circuit boards operating at higher frequencies (≥10 GHz).

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Section: Introductionmentioning

confidence: 99%

Poly(ester imide)s Possessing Low Coefficients of Thermal Expansion and Low Water Absorption (V). Effects of Ester-linked Diamines with Different Lengths and Substituents

Hasegawa

Hishiki

2020

Polymers

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“…As an outstanding polymer material, polyimides (PIs) exhibit high thermal stability, excellent mechanical and dielectric properties as well as good chemical resistance, and are applied in diverse fields such as aerospace, composites, gas separation and optoelectronics . However, a deep color and the poor processing ability of PI films are the main limitations for their applications as optical film.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of highly transparent and heat‐resistant polyimides containing bulky pendant moieties

Zheng

et al. 2019

Polymer International

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A new diamine with bulky pendant biphenyl and ortho-position dimethyl structures, 4,4 ′ -((1,1 ′ -biphenyl)-4-ylmethylene)bis(2,6dimethylaniline), was synthesized via a one-pot reaction of 4-biphenyl carboxaldehyde and 2,6-dimethylaniline. The diamine was employed to polymerize with several dianhydrides via one-step condensation under high-temperature conditions. The light yellow or colorless polyimide (PI) films obtained were found to have cut-off wavelengths in the range 286-358 nm and transmittance over 80% in the visible region (400-780 nm). Meanwhile, these PIs possessed excellent solubility in common organic solvents, even in low-boiling-point solvents such as chloroform (CHCl 3 ), dichloromethane (CH 2 Cl 2 ) and tetrahydrofuran. The glass transition temperatures (T g ) of the PIs were determined to exceed 343 ∘ C, even to 456 ∘ C. All PI films were flexible with a tensile strength of 78-119 MPa, a Young's modulus of 2.0-2.5 GPa and elongation at break of 4.0%-8.2%. Therefore, these colorless PIs can be used as candidate materials for flexible display substrates.

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“…Based on the previous decades of research on the origination of coloration in traditional all-aromatic PI films, the researchers revealed many effective procedures to prohibit the formation of intra-or intermolecular charge transfer complexes (CTC) between the electron-donating diamine moiety and the electron-accepting dianhydride moiety so as to improve the optical transparency of the PI films [11][12][13]. At present, the effective means to develop CPI films mainly include introducing groups with high electronegativity characteristics, such as trifluoromethyl groups, sulphone groups, or substituents with non-conjugated characteristics, such as aliphatic or alicyclic groups, or groups with large molar volume-such as naphthalene, fluorene, or cardo groups-into the PI molecular chains [14][15][16][17][18][19][20]. Although various CPI films have been developed in the literature by these methodologies, much of them still cannot be practically used due to the absence of dimensional stability at elevated temperatures.…”

mentioning

confidence: 99%

Reduced Coefficients of Linear Thermal Expansion of Colorless and Transparent Semi-Alicyclic Polyimide Films via Incorporation of Rigid-Rod Amide Moiety: Preparation and Properties

Jiang

Wang

et al. 2020

Polymers

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Semi-alicyclic colorless and transparent polyimide (CPI) films usually suffer from the high linear coefficients of thermal expansion (CTEs) due to the intrinsic thermo-sensitive alicyclic segments in the polymers. A series of semi-alicyclic CPI films containing rigid-rod amide moieties were successfully prepared in the current work in order to reduce the CTEs of the CPI films while maintaining their original optical transparency and solution-processability. For this purpose, two alicyclic dianhydrides, hydrogenated pyromellitic anhydride (HPMDA, I), and hydrogenated 3,3',4,4'-biphenyltetracarboxylic dianhydride (HBPDA, II) were polymerized with two amide-bridged aromatic diamines, 2-methyl-4,4'-diaminobenzanilide (MeDABA, a) and 2-chloro-4,4'-diaminobenzanilide (ClDABA, b) respectively to afford four CPI resins. The derived CPI resins were all soluble in polar aprotic solvents, including N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc). Flexible and tough CPI films were successfully prepared by casing the PI solutions onto glass substrates followed by thermally cured at elevated temperatures from 80 • C to 250 • C. The MeDABA derived PI-I a (HPMDA-MeDABA) and PI-II a (HBPDA-MeDABA) exhibited superior optical transparency compared to those derived from ClDABA (PI-I b and PI-II b ). PI-I a and PI-II a showed the optical transmittances of 82.3% and 85.8% at the wavelength of 400 nm with a thickness around 25 µm, respectively. Introduction of rigid-rod amide moiety endowed the HPMDA-PI films good thermal stability at elevated temperatures with the CTE values of 33.4 × 10 −6 /K for PI-I a and 27.7 × 10 −6 /K for PI-I b in the temperature range of 50-250 • C. Comparatively, the HBPDA-PI films exhibited much higher CTE values. In addition, the HPMDA-PI films exhibited good thermal stability with the 5% weight loss temperatures (T 5% ) higher than 430 • C and glass transition temperatures (T g ) in the range of 349-351 • C.The polymeric optical films with high thermal stability, high dimensional stability at elevated temperatures, high optical transparency, and high tensile properties are highly desired in modern optoelectronic areas, such as substrates or covering windows for flexible active matrix organic light-emitting diodes (AMOLED) devices, substrates for organic photovoltaic (OPV) solar cells, and so on [1][2][3]. Conventional polymeric optical films, such as polyolefin and polyester films usually suffer from the poor thermal and dimensional stability while the standard high-temperature resistant polymer films, such as the wholly aromatic polyimide (PI) films often exhibit highly colored appearance and poor optical transparency in the visible light region [4]. That is to say, the molecular structure factors that affect the optical and thermal properties of polymer films are usually contradictory. The structural factors that can improve the thermal stability of polymer films often reduce the optical properties of the films at the same time, and vice versa. Thus, it is a changeling research topic to dev...

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Highly transparent polyimide hybrids for optoelectronic applications

Cited by 129 publications

References 242 publications

Poly(ester imide)s Possessing Low Coefficients of Thermal Expansion and Low Water Absorption (V). Effects of Ester-linked Diamines with Different Lengths and Substituents

Poly(ester imide)s Possessing Low Coefficients of Thermal Expansion and Low Water Absorption (V). Effects of Ester-linked Diamines with Different Lengths and Substituents

Synthesis of highly transparent and heat‐resistant polyimides containing bulky pendant moieties

Reduced Coefficients of Linear Thermal Expansion of Colorless and Transparent Semi-Alicyclic Polyimide Films via Incorporation of Rigid-Rod Amide Moiety: Preparation and Properties

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