Optically transparent and thermally conductive composite films of α-alumina and highly refractive polyimide

Sato, Kimiyasu; Tominaga, Yoshihiro; Imai, Yusuke

doi:10.1007/s00289-022-04528-0

Cited by 4 publications

(4 citation statements)

References 36 publications

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“…In the case of PI composite films, the incorporation of inorganic fillers has been studied to enhance their mechanical and thermal properties. Inorganic materials such as metal oxides [ 14 ], organo-clays [ 15 ], boron nitride [ 16 ], carbon nanomaterials [ 17 , 18 ], silica nanoparticles [ 19 , 20 , 21 , 22 ], and polysilsesquioxane (POSS) [ 23 , 24 ] have been widely used to fabricate transparent PI/inorganic composite films [ 6 ]. Among these inorganic materials, silica nanoparticles offer advantages such as abundance, low cost, good adsorption, high mechanical strength, a low dielectric constant, and excellent chemical and thermal stabilities [ 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Mechanical and Thermal Properties of Polyimide Films Using Hydrophobic Fumed Silica Fillers

Yeob,

Hong,

Koh

et al. 2024

Polymers

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Polyimide (PI) composite films with enhanced mechanical properties were prepared by incorporating modified fumed silica (FS) particles while preserving their optical and thermal characteristics. The PI matrix was synthesized using a fluorinated diamine, a fluorinated dianhydride, and a rigid biphenyl dianhydride via chemical imidization. Commercially available FS particles, including unmodified FS particles (0-FS) and particles modified with dimethyl (2-FS), trimethyl (3-FS), octyl (8-FS), octamethylcyclotetrasiloxane (D4-FS), and polydimethylsiloxane (PDMS-FS) were used. Scanning electron microscope images and nitrogen adsorption–desorption isotherms revealed well-defined porous structures in the FS particles. The water contact angles on the composite films increased compared to those of the pristine PI films, indicating improved water resistance. The PI/0-FS films exhibited a typical trade-off relationship between tensile modulus and elongation at break, as observed in conventional composites. Owing to the poor compatibility and agglomeration of the PDMS-FS particles, the PI/PDMS-FS composite films exhibited poor mechanical performance and diminished optical characteristics. Although the longer-chained FS particles (8- and D4-FS) improved the tensile modulus of the PI film by up to 12%, a reduction of more than 20% in toughness was observed. The PI composite films containing the methylated FS particles (2- and 3-FS) outperformed 8- and D4-FS in terms of mechanical properties, with PI/3-FS films showing an over 10% increased tensile modulus (from 4.07 to 4.42 GPa) and 15% improved toughness (from 6.97 to 8.04 MJ/m3) at 7 wt. % silica loading. Except for the PI/PDMS-FS composites, all composite film samples exhibited more than 86% transmittance at 550 nm. Regarding thermal properties, the glass transition temperature (Tg) and thermal stability remained stable for most composite films. In addition, PI/3-FS films demonstrated enhanced dimensional stability with lower coefficients of thermal expansion (from 47.3 to 34.5 ppm/°C). Overall, this study highlights the potential of incorporating specific modified FS particles to tailor the mechanical, optical, and thermal properties of PI composite films.

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Section: Introductionmentioning

confidence: 99%

Enhanced Mechanical and Thermal Properties of Polyimide Films Using Hydrophobic Fumed Silica Fillers

Yeob,

Hong,

Koh

et al. 2024

Polymers

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“…13,14 Huge researches have been done to figure out this difficulty. [15][16][17][18][19] In terms of the theory of the CTC formation, 20,21 numerous approaches have been found out, including changing monomer linearity and stiffness, incorporations of bulky substituents, flexible segments and asymmetric units, and so on. Comparing with other approaches that sacrifices thermal performance to enhance optical property, the introduction of asymmetric moieties, which with noticeable steric effect can block the π-flip rotational motions and increase the interchain distance, can combine remarkable optical and thermal properties at the same time, 22,23 such as 2,2 0 -bis(trifluoromethyl)benzidine (TFMB) and 2,2 0dimethylbenzidine (DMB).…”

Section: Introductionmentioning

confidence: 99%

“…While, common PI films expose deep yellow or brown in color on account of charge transfer complex (CTC), influencing the application in optical field 13,14 . Huge researches have been done to figure out this difficulty 15–19 . In terms of the theory of the CTC formation, 20,21 numerous approaches have been found out, including changing monomer linearity and stiffness, incorporations of bulky substituents, flexible segments and asymmetric units, and so on.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of novel colorless polyimides from benzimidazole diamines with various linearity

Xu,

Ke,

et al. 2024

Journal of Polymer Science

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To synthesize colorless superheat‐resistant polyimide films, one of the valid approaches is the incorporation of the asymmetric and warped structures in the main chain. Applying this approach on 5(6)‐amino‐2‐(4‐aminobenzene)benzimidazole (PABZ) and changing its linearity, 6, 5′‐diamine‐2′‐methyl‐1‐methyl‐2‐phenylbenzimidazole (5a) and 6, 3′‐diamine‐2′‐methyl‐1‐methyl‐2‐phenylbenzimidazole (5b) were devised and synthesized successfully, then polymerized with 1,2,4,5‐cyclohexanetetracarboxylic dianhydride (HPMDA). The prepared poly(benzimidazole imide)s (PBIIs) with the rigid main chain and loose packing had the excellent heat‐resistant level (Tg > 400°C) and optical properties (T400 > 80%). Besides, the alterations resulting from various linearities were discussed comprehensively. This research is beneficial to the application of optical field, providing a promising candidate of heat‐resistant colorless materials.

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“…To maintain high electrical insulating properties, ceramic fillers must be used. Among the ceramic fillers, the most widely explored ones include: carbides, such as carbide-based MXenes [16] and silicon carbide (SiC) [23,24]; oxides, such as silicon oxide (SiO 2 ) [25,26], aluminum oxide (Al 2 O 3 ) [27], and magnesium oxide (MgO) [28,29]; and nitrides, such as aluminum nitride (AlN) [30,31] and boron nitride (BN) [32][33][34]. Among these, hexagonal boron nitride (BN) is considered highly promising [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Thermally Conductive and Electrically Insulating Polymer-Based Composites Heat Sinks Fabricated by Fusion Deposition Modeling

Bagatella,

Cereti,

Manarini

et al. 2024

Polymers

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This study explores the potential of novel boron nitride (BN) microplatelet composites with combined thermal conduction and electrical insulation properties. These composites are manufactured through Fusion Deposition Modeling (FDM), and their application for thermal management in electronic devices is demonstrated. The primary focus of this work is, therefore, the investigation of the thermoplastic composite properties to show the 3D printing of lightweight polymeric heat sinks with remarkable thermal performance. By comparing various microfillers, including BN and MgO particles, their effects on material properties and alignment within the polymer matrix during filament fabrication and FDM processing are analyzed. The characterization includes the evaluation of morphology, thermal conductivity, and mechanical and electrical properties. Particularly, a composite with 32 wt% of BN microplatelets shows an in-plane thermal conductivity of 1.97 W m−1 K−1, offering electrical insulation and excellent printability. To assess practical applications, lightweight pin fin heat sinks using these composites are designed and 3D printed. Their thermal performance is evaluated via thermography under different heating conditions. The findings are very promising for an efficient and cost-effective fabrication of thermal devices, which can be obtained through extrusion-based Additive Manufacturing (AM), such as FDM, and exploited as enhanced thermal management solutions in electronic devices.

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Optically transparent and thermally conductive composite films of α-alumina and highly refractive polyimide

Cited by 4 publications

References 36 publications

Enhanced Mechanical and Thermal Properties of Polyimide Films Using Hydrophobic Fumed Silica Fillers

Enhanced Mechanical and Thermal Properties of Polyimide Films Using Hydrophobic Fumed Silica Fillers

Synthesis of novel colorless polyimides from benzimidazole diamines with various linearity

Thermally Conductive and Electrically Insulating Polymer-Based Composites Heat Sinks Fabricated by Fusion Deposition Modeling

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