Enhancing photoconductivity of aromatic polyimide films by incorporating fluorinated dianhydrides and main chain triphenylamine structure

Takizawa, Kazuhiro; Fukuchi, S.; Chiaki, T Oguchi; Ishige, Ryohei; Asai, Shigeo; Ando, Shinji

doi:10.1016/j.polymer.2018.10.025

Cited by 9 publications

(9 citation statements)

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“…Classically, intra- and intermolecular charge transfer (CT) interactions between the electron-donating diamine and electron-accepting aromatic dianhydride are considered the main reason for the coloration of aromatic polyimides, and the stiff and ordered structure of the molecular chains led to the insolubility or infusibility of aromatic polyimides, which deteriorate their processing and applications [6,7,8,9]. In this regard, extensive reports [10,11,12,13] have focused on the structure modification of polyimides, e.g., the introduction of a fluorinated structure, cycloaliphatic segments, bulky pendant substituents, flexible and unsymmetrical linkages and electron withdrawing chlorine atoms in the backbone of polymers, aiming at reducing several types of chain-chain interactions such as CT complexes, electronic polarization interactions and chain packing (e.g., crystallinity) to obtain colorless and soluble polyimides.…”

Section: Introductionmentioning

confidence: 99%

Soluble Polyimides Bearing (cis, trans)-Hydrogenated Bisphenol A and (trans, trans)-Hydrogenated Bisphenol A Moieties: Synthesis, Properties and the Conformational Effect

Wang

Hou

et al. 2019

Polymers

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In this work, hydrogenated bisphenol A (HBPA) based dinitro mixed isomers (1a′ and 1a) were synthesized and separated via vacuum distillation under the monitor of DSC and 1H NMR. Corresponding diamines (2a′ and 2a) were separately polycondensed with five commercial dianhydrides via a two-step thermal imidization to obtain PI-(1′-5′) and PI-(1-5). All the polyimides could afford flexible, tough, and transparent films, and most of them were readily soluble not only in common polar solvents like DMAc, but also in low boiling point solvents such as chloroform. 1H NMR spectra of the polyimides demonstrated that HBPA moiety showed no conformation changes during the preparation of polymers. For a given dianhydride, PI-(1-5) exhibited better thermal stability than that of PI-(1′-5′), this can be attributed that the equatorial, equatorial C–O in PI-(1-5) promoted denser and more regular molecular chain stacking, as can be evidenced by the WAXD and geometric optimization results. Additionally, when the dianhydride was ODPA, BPADA or 6FDA, no apparent difference was found in either the transmittance or solubility between two series of polyimides, which could be attributed that twisted and flexible ether linkages, as well as bulky substituents, led to the “already weakened” inter- and intramolecular CT interaction and cohesive force. However, when it came to rigid and stiff dianhydride, e.g., BPDA, PI-3′ took an obvious advantage over PI-3 in transmittance and solubility, which was possibly owed to the larger molecular chain d-spacing imparted by equatorial, axial C–O. An overall investigation of PI-(1′-5′) and PI-(1-5) on aspects of thermal, mechanical, morphological, soluble and optical performance values was carried out, and the conformation effects of HBPA isomers on the properties of two series of polyimides were discussed in detail.

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Section: Introductionmentioning

confidence: 99%

Soluble Polyimides Bearing (cis, trans)-Hydrogenated Bisphenol A and (trans, trans)-Hydrogenated Bisphenol A Moieties: Synthesis, Properties and the Conformational Effect

Wang

Hou

et al. 2019

Polymers

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“…For fully-aromatic PIs, their intense coloration and high absorption in the ultraviolet-visible region have proved to be a consequence of easily formed charge transfer complexes (CTC) in their highly conjugated molecular chains. Ando and coworkers have systematically investigated the relationship between molecular structures and coloration of PIs [ 15 , 16 , 17 ]. In general, the electron-deficient dianhydride units and electron-rich diamine units act as the electron donor and acceptor, respectively.…”

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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“…In recent years, with the rapid development of the microelectronic and optoelectronic industry, the applications of PI films in these areas have attracted increasing attention from both academic research and engineering fabrications. For instance, the research on the adjustment of optical transparency and colors of PI films so as to meet the property requirements of high-tech areas has been becoming one of the most vigorous topics in the PI materials [4][5][6]. Standard PI films, characterized by the first commercially available poly(pyromellitic dianhydride-co-4,4 -oxydianline) (PMDA-ODA) commercialized by DuPont company, USA in the 1960s with the trademark of Kapton ® , usually exhibit a golden yellow color and a certain extent of optical transparency owing to the absorption of visible light caused by the intra-and intermolecular charge transfer behaviors in the polymer chains [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Preparation and Properties of Inherently Black Polyimide Films with Extremely Low Coefficients of Thermal Expansion and Potential Applications for Black Flexible Copper Clad Laminates

et al. 2020

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In the current work, a series of black polyimide (PI) films with excellent thermal and dimensional stability at elevated temperatures were successfully developed. For this purpose, two aromatic diamines including 4,4′-iminodianline (NDA) and 2-(4-aminophenyl)-5- aminobenzimidazole (APBI) were copolymerized with pyromellitic dianhydride (PMDA) to afford PIs containing imino groups (–NH–) in the molecular structures. The referenced PI film, PI-ref, was simultaneously prepared from PMDA and 4,4′-oxydianiline (ODA). The introduction of imino groups endowed the PI films with excellent blackness and opaqueness with the optical transmittance lower than 2% at the wavelength of 600 nm at a thickness of 25 μm and lightness (L*) below 10 for the CIE (Commission International Eclairage) Lab optical parameters. Meanwhile, the introduction of rigid benzimidazole units apparently improved the thermal and dimensional stability of the PI films. The PI-d film based on PMDA and mixed diamines (NDA:APBI = 70:30, molar ratio) showed a glass transition temperature (Tg) of 445.5 °C and a coefficient of thermal expansion (CTE) of 8.9 × 10−6/K in the temperature range of 50 to 250 °C, respectively. It is obviously superior to those of the PI-a (PMDA-NDA, Tg = 431.6 °C; CTE = 18.8 × 10−6/K) and PI-ref (PMDA-ODA, Tg = 418.8 °C; CTE: 29.5 × 10−6/K) films.

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Enhancing photoconductivity of aromatic polyimide films by incorporating fluorinated dianhydrides and main chain triphenylamine structure

Cited by 9 publications

References 50 publications

Soluble Polyimides Bearing (cis, trans)-Hydrogenated Bisphenol A and (trans, trans)-Hydrogenated Bisphenol A Moieties: Synthesis, Properties and the Conformational Effect

Soluble Polyimides Bearing (cis, trans)-Hydrogenated Bisphenol A and (trans, trans)-Hydrogenated Bisphenol A Moieties: Synthesis, Properties and the Conformational Effect

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

Preparation and Properties of Inherently Black Polyimide Films with Extremely Low Coefficients of Thermal Expansion and Potential Applications for Black Flexible Copper Clad Laminates

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