Composition design and properties investigation of BPDA/PDA/TFDB co‐polyimide films with low dielectric permittivity

Li, Xiaolan; Lei, Huanyu; Guo, Jiacong; Wang, Jianhua; Qi, Shengli; Tian, Guofeng; Wu, Dezhen

doi:10.1002/app.47989

Cited by 45 publications

(28 citation statements)

References 39 publications

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“…In general, 2,2′-bis(trifluoromethyl)-[1,1′-biphenyl]-4,4′-diamine (TFDB) based PIs possessed high rigidity and showed good thermal stability. − Thus, in this work, the polymers were designed based on the polycondensation of 1S,2R,4S,5R-cyclohexanetetracarboxylic dianhydride (HPMDA) and TFDB to balance the high-temperature stability, optical transparency, and other properties. Because of its reduced ring strain, HPMDA was less reactive in polycondensation reaction in the presence of isoquinoline (Figure a), which consequently gave rise to poly(amic acid) with low molecular weights that were inadequate to form a continuous film as described in detail in section .…”

Section: Resultsmentioning

confidence: 99%

Uniformly Dispersed Nanoparticles in Modified Polyimides Exhibiting High Thermal Stability and Bright Emissions in the Telecommunication Window

Fan

Pang

et al. 2021

ACS Appl. Nano Mater.

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Excellent optically active photonic composites are indispensable for designing polymeric waveguide amplifiers which may spur the development of the next generation of high efficiency communication systems. However, due to the poor thermal stability, low light transmittance, low solids loading and non-uniform nanoparticle dispersion, most existing materials and composites are unable to meet the waveguide requirements for operation at high-power needed to achieve high optical gain. Thus, 30 nm-sized core–shell NaYF4:Yb,Er,Ce@NaYF4 nanoparticles coated with oleic acid (OA) were designed to emit strongly at ∼1530 nm which is within the low loss telecommunication window of 1300–1650 nm which most communication devices operate in. By engineering the nanoparticle interfacial interactions within the solution and polymer matrices, nanoparticle agglomeration is prevented to limit any undesired scattering losses. In this work, we report the synthesis of a series of polyimide (PI)-based matrices that were modified to improve their compatibility with the nanoparticle’s surface chemistry and at the same time exhibit excellent thermal stability and optical transparency. Specifically, the carboxyl group was introduced to improve the dispersion of nanoparticles at high solids loading and also the solubility of PIs in solvents required for composite film formation. After incorporating the nanoparticles together with the modified polyimide matrix, a photonic composite film with excellent thermal stability (T g = 314 °C, T degrade = 383 °C), high solids loading (∼10.2 vol %), and bright emissions (1530 nm) within the telecommunication window was fabricated.

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Section: Resultsmentioning

confidence: 99%

Uniformly Dispersed Nanoparticles in Modified Polyimides Exhibiting High Thermal Stability and Bright Emissions in the Telecommunication Window

Fan

Pang

et al. 2021

ACS Appl. Nano Mater.

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“…Models with a large number of repeat units require an extremely long simulation time and large computer memory, whereas many too few repeat units are not enough to represent the conformations of a real polymer chain. Fortunately, previous researchers − have reported reasonable results when they used 10–20 repeat units for PI simulation.…”

Section: Experimental Sectionmentioning

confidence: 91%

Structural Evolution of Macromolecular Chain During Pre-imidization Process and Its Effects on Polyimide Film Properties

et al. 2020

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Pre-imidization has been found to have a determining role on the final properties of polyimide (PI) films. In this work, a series of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)/2,2′-bis(trifluoromethyl)benzidine (TFMB) PI models with specified pre-imidization degree (pre-ID) were constructed and analyzed on the basis of molecular dynamic (MD) simulation to reveal the real-time evolution of structure and properties that occurred during the pre-imidization process. The MD results indicated that the T g of the models increased obviously with increasing pre-ID, which corresponded to the increase of rigid PI chain segments that restricted the mobility of molecular chains. In addition, the increase of fractional free volume and mean square end-to-end distance indicated looser chain packing and more extended chain conformation during the pre-imidization process. As a further verification, a series of corresponding PI films were experimentally prepared via a controlled partially pre-imidization process. Mechanical properties of the prepared PI films were tested to be significantly enhanced, and the coefficient of thermal expansion decreased from 61.5 to 47.6 ppm/°C with pre-ID increasing from 0% to 100%, which could be attributed to the orderly molecular chain arrangement formed during the chemical pre-imidization process, as disclosed by MD simulation. This work paves the way for the observation of the real-time structure and property evolutions of PI materials, especially during the pre-imidization process.

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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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Composition design and properties investigation of BPDA/PDA/TFDB co‐polyimide films with low dielectric permittivity

Cited by 45 publications

References 39 publications

Uniformly Dispersed Nanoparticles in Modified Polyimides Exhibiting High Thermal Stability and Bright Emissions in the Telecommunication Window

Uniformly Dispersed Nanoparticles in Modified Polyimides Exhibiting High Thermal Stability and Bright Emissions in the Telecommunication Window

Structural Evolution of Macromolecular Chain During Pre-imidization Process and Its Effects on Polyimide Film Properties

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

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