Highly transparent preimidized semi-alicyclic polyimide varnishes with low curing temperatures and desirable processing viscosities at high solid contents: preparation and applications for LED chip passivation

Wu, Xiaowen; Liu, Jingang; Jiang, Ganglan; Zhang, Yan; Guo, Chenyu; Zhang, Yaojia; Lin, Qi; Zhang, Xiumin

doi:10.1007/s10854-018-0321-5

Cited by 11 publications

(13 citation statements)

References 24 publications

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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.…”

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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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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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“…Hydrogenated 3,3 ,4,4 -biphenyltetracarboxylic dianhydride (HBPDA) was synthesized in our laboratory according to our previous work [9], or it can be purchased from Xinyuankesheng Co. Ltd. (Shandong, China) and dried at 150 • C in vacuo for 24 h prior to use. 4,4 -Oxydianiline (ODA) was purchased from Wakayama Co. Ltd. (Osaka, Japan) and used as received.…”

Section: Methodsmentioning

confidence: 99%

“…The PI (HBPDA-ODA) matrix (PI-1) was synthesized according to our previously reported procedure [9]. The white fibrous resin was dried at 80 • C in vacuo for 24 h. 1 H-NMR (DMSO-d 6 , ppm): 7.34-7.31 (d, 2H), 7.16-7.13 (d, 4H), 3.20-2.97 (m, 2H), 2.95-2.78 (m, 2H), 2.17-1.96 (m, 4H), 1.63-1.59 (m, 4H), 1.32-1.14 (m, 4H), and 1.03-0.96 (m, 2H).…”

Section: Pi Synthesis and Film Preparationmentioning

confidence: 99%

“…Colorless and transparent polyimide (CPI) films have been paid ever-increasing attention in recent years due to their excellent combined thermal, optical, and dielectric properties [1][2][3]. CPI films have been thought to be good candidates for functional components for advanced optoelectronic fabrication, such as substrates for flexible display devices [4][5][6], flexible organic solar cells [7], and flexible heater for wearable sensors [8]; encapsulants for displays or electronic chips [9]; and other high-tech applications. Various CPI films, including the wholly aromatic ones containing fluoro-containing units [10][11][12] and the wholly alicyclic or semi-alicyclic ones containing alicyclic or aliphatic segments [13][14][15], have been well designed and developed in the past decades.…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of Flame Retardancy of Colorless and Transparent Semi-Alicyclic Polyimide Film from Hydrogenated-BPDA and 4,4′-oxydianiline via the Incorporation of Phosphazene Oligomer

Jiang

Zhang

et al. 2020

Polymers

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Enhancement of flame retardancy of a colorless and transparent semi-alicyclic polyimide (PI) film was carried out by the incorporation of phosphazene (PPZ) flame retardant (FR). For this purpose, PI-1 matrix was first synthesized from hydrogenated 3,3′,4,4′-biphenyltetracarboxylic dianhydride (HBPDA) and 4,4′-oxydianiline (ODA). The soluble PI-1 resin was dissolved in N,N-dimethylacetamide (DMAc) to afford the PI-1 solution, which was then physically blended with PPZ FR with the loading amounts in the range of 0–25 wt.%. The PPZ FR exhibited good miscibility with the PI-1 matrix when its proportion was lower than 10 wt.% in the composite films. PI-3 composite film with the PPZ loading of 10 wt.% showed an optical transmittance of 75% at the wavelength of 450 nm with a thickness of 50 μm. More importantly, PI-3 exhibited a flame retardancy class of UL 94 VTM-0 and reduced total heat release (THR), heat release rate (HRR), smoke production rate (SPR), and rate of smoke release (RSR) values during combustion compared with the original PI-1 film. In addition, PI-3 film had a limiting oxygen index (LOI) of 30.9%, which is much higher than that of PI-1 matrix (LOI: 20.1%). Finally, incorporation of PPZ FR decreased the thermal stability of the PI films. The 10% weight loss temperature (T10%) and the glass transition temperature (Tg) of the PI-3 film were 411.6 °C and 227.4 °C, respectively, which were lower than those of the PI-1 matrix (T10%: 487.3 °C; Tg: 260.6 °C)

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“…The liquid crystal cells fabricated with the organo-soluble PI alignment layer exhibited low curing temperature (<200°C), high VHR, and good alignment ability to liquid crystal molecules. In the current work, as one of continuous work developing high performance PI materials for optoelectronic applications [31][32][33][34], a series of imidized PIs were prepared from an ester-linked semi-alicyclic dianhydride and aromatic diamines. Compared with the PI alignment layers derived from substitutedtetralin dianhydrides in our previous work [34], the current PI systems are expected to provide better comprehensive properties for the derived PI alignment layers, including higher optical transparency, lower curing temperature, and higher degree of imidization at the TFT-LCD processing temperature (230°C).…”

mentioning

confidence: 99%

Synthesis and characterization of soluble ester-containing polyimide alignment layers with high voltage holding ratio features and potential applications in TFT-LCDs

Zhi¹,

Bi²,

Liu³

et al. 2019

Express Polym. Lett.

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Polyimide (PI) represents a class of high performance heteroaromatic polymers characterized by excellent thermal and environmental stability, high mechanical and dielectric properties as well as flexible molecular structure designability [1-3]. Various functionalities have been achieved for PIs via elaborate combination of specific dianhydride and diamine monomers so as to meet the property demands of high-tech applications [4-6]. Among the various functional PIs, semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines proved to possess the best combined properties considering the polymerization reactivity and the acidity/basicity of the starting monomers [7]. Thus, such kinds of semi-alicyclic PIs usually exhibited superior thermal and mechanical properties, and higher molecular weights to their analogous PIs derived from aromatic dianhydrides and alicyclic diamines or from both of alicyclic dianhydride and diamines [8]. Good comprehensive properties of semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines make them much attractive in optoelectronic fields in recent years [9-11]. The successful 923

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Highly transparent preimidized semi-alicyclic polyimide varnishes with low curing temperatures and desirable processing viscosities at high solid contents: preparation and applications for LED chip passivation

Cited by 11 publications

References 24 publications

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

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

Enhancement of Flame Retardancy of Colorless and Transparent Semi-Alicyclic Polyimide Film from Hydrogenated-BPDA and 4,4′-oxydianiline via the Incorporation of Phosphazene Oligomer

Synthesis and characterization of soluble ester-containing polyimide alignment layers with high voltage holding ratio features and potential applications in TFT-LCDs

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