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Synthesis and electro-optic properties of novel Y-type polyimide containing nitrothiazolylazodioxyphenyl group
摘要： New Y-type polyimide (5) containing nitrothiazolylazodioxyphenyl groups as nonlinear optical (NLO) chromophores, which are components of the polymer backbone, was prepared and characterized. Polyimide 5 is soluble in common organic solvents such as N,N-dimethylformamide and dimethylsulfoxide. Polyimide 5 shows a thermal stability up to 300 °C in thermogravimetric analysis with glass-transition temperature (Tg) obtained from differential scanning calorimetry near 130 °C. The second harmonic generation (SHG) coefficient (d33) of poled polymer film at the 1064 nm fundamental wavelength is around 2.32 pm/V. The dipole alignment of polymer 5 exhibits a thermal stability even at 5 °C higher than Tg, and there is no SHG decay below 135 °C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.
关键词： thermogravimetric analysis (TGA),NLO,dipole alignment,SHG coefficient,differential scanning calorimetry (DSC),polyimide
更新于2025-09-11 14:15:04
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The In-plane Orientation and Thermal Mechanical Properties of the Chemically Imidized Polyimide Films
摘要： The thermal and mechanical properties of the chemically imidized polyimide (CIPI) films and thermally imidized polyimide (TIPI) films were investigated systematically. Experimental results indicated that the CIPI films show dramatically enhanced tensile strength and modulus with obviously reduced coefficient of thermal expansion (CTE) in comparison with TIPI films. These enhancements results from the high in-plane orientation and close packing of the CIPI backbones. Compared with thermal imidization which starts at about 140 °C, the chemical imidization activated by acetic anhydride and isoquinoline initiates the cyclization even at room temperature. The resulting imide rings restrict the mobility of polymer chains and lead to the in-plane orientation with solvent evaporation. Additionally, fewer small molecules remain in the films after treated at 120 °C by chemical imidization than by thermal imidization. The polymer chain plasticization caused by the evaporation of small molecules at high temperature is obviously restricted. Moreover, the partially imidized polymer inhibits the decomposition of mainchains that occurs at subsequent high temperature process, being beneficial to the formation of high molecular weight PI films. Hence, chemical imidization pathway shows apparent advantage to produce PI films with great combined properties, including high modulus, strength and toughness, as well as high thermal dimension stability etc.
关键词： In-plane orientation,CTE,Thermal imidization,Chemical imidization,Polyimide film
更新于2025-09-10 09:29:36
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Towards solution-processable, thermally robust, transparent polyimide-chain-end tethered organosilicate nanohybrids
摘要： The main challenge to developing future display substrates is to synthesize flexible substrate materials that also have excellent optical and thermal properties, and low thermal expansion number. In this study, a novel trifluoromethylated asymmetric aromatic diamine, 4-[[4-(4-amino-2-trifluoromethylphenoxy)phenyl]sulfonyl-3-(trifluoromethyl)]benzenamine (AFPSFB), was synthesized through nucleophilic substitution. Conventional two-step polycondensation of AFPSFB with commercially available tetracarboxylic dianhydrides enabled the fabrication of fully or semi-aromatic polyimides (PIs). The resulting PIs were highly soluble in polar aprotic solvents with good optical and thermal properties. Next, polyhedral oligomeric silsesquioxane containing an amine group (NH2-POSS) was reacted with the resulting soluble PI. All the PI-POSS nanohybrids displayed excellent optical properties, including high transparency (> 91% at 400 nm), low refractive index (< 1.5589), and very small birefringence (< 0.0025 at 637 nm). End-capping of the POSS and chemical bonding between the POSS and PIs significantly enhanced the thermal and electrical properties. The results provide useful information for designing molecular architectures for manufacturing high-performance flexible substrates in future display devices.
关键词： Organosilicate,Optical transparency,Dielectric constant,Thermal stability,Soluble polyimide
更新于2025-09-10 09:29:36
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Improving the stability of silver nanowire/polyimide composite films for transparent film heaters
摘要： Flexible and transparent heaters have gradually attracted considerable attention because of its widely application in defrosting or demisting windows and medical thermotherapy. The stability of the heater under ambient conditions during working is one of the important properties. In this paper, we fabricated a highly stable and transparent film heater (TFH) through a simple drop-coating approach with burying silver nanowires (AgNWs) between colorless polyimide (cPI) and polymethyl methacrylate (PMMA). The developed TFH exhibited higher stability with the resistance increasing by 17% only for the initial value of 9.6 ? after accelerating test at 105 °C and 100% relative humidity for 36 h, which was much lower than that of 83% for TFH without PMMA. Furthermore, the fabricated film heater covered with PMMA showed extreme stability in hydrogen sulfide oven. Meanwhile, there was no significant influence in the transmittance, mechanical flexibility and heating performance after coating a PMMA layer. Finally, we applied the film heater to demisting demonstration.
关键词： transparent film heaters,polyimide,polymethyl methacrylate,silver nanowires,stability
更新于2025-09-10 09:29:36
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Preparation and properties of heat-sealable polyimide films with comparable coefficient of thermal expansion and good adhesion to copper matrix
摘要： A series of thermoplastic polyimide (PI) films (PI-1~PI-5) with intrinsic heat sealability have been synthesized by the high-temperature polycondensation reaction of asymmetrical 2,3,3?,4?-oxydiphthalic anhydride (aODPA) and various aromatic diamines in order to meet the demands of advanced flexible copper clad laminates (FCCL). The derived PI resins had good solubility in polar aprotic solvents, such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) at a solid content up to 20 wt%. Flexible and tough films could be cast from the PI/NMP solution and the films exhibited tensile strength higher than 83 MPa. Among the developed PIs, those derived from aODPA and benzimidazole-containing diamines, including PI-4 from aODPA and 2-(4-aminophenyl)-5-aminobenzimidazole (4APBI) and PI-5 from aODPA and 2-(3-aminophenyl)-5-aminobenzimidazole (3APBI) exhibited the highest thermal stability (glass transition temperatures, Tg > 340°C), lowest linear coefficients of thermal expansion (CTE < 35·10–6 1/K), and superior adhesion to copper foil (peeling strength >1.0 N/mm). Flexible copper clad laminate (FCCL) with no curling was successfully prepared from PI-4 and copper foil.
关键词： tailor-made polymers,flexible copper clad laminates,polyimide,heat sealability,low CTE
更新于2025-09-10 09:29:36
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Inkjet Printing of SiO2 Hollow Spheres/Polyimide Hybrid Films for Foldable Low-k ILD
摘要： We demonstrate inkjet printing as a viable method for flexible interlayer dielectrics (ILDs) films with a low dielectric constant, excellent mechanical characteristics, and thermal properties in foldable organic light emitting diodes (OLEDs). SiO2 hollow spheres (SHSs)/polyimide (PI) hybrid films were printed by SiO2 coated polystyrene (PS) ink and PI ink. The relative permittivity of the hybrid films decreased from 3.45 to 1.87. The thermally stable PI fims maintained their weight below 500 °C from the TGA result. The dielectric constant and current density retained their properties after 50,000 cycles of bending at a 1 mm bend radius. We propose that the inkjet printing of SHSs/PI hybrid films described herein is a promising approach for flexible ILDs in foldable OLEDs.
关键词： SiO2 hollow sphere,polyimide,foldable OLEDs,low-k material,inkjet printing,interlayer dielectric
更新于2025-09-10 09:29:36
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[IEEE 2017 IEEE 12th Nanotechnology Materials and Devices Conference (NMDC) - Singapore (2017.10.2-2017.10.4)] 2017 IEEE 12th Nanotechnology Materials and Devices Conference (NMDC) - Measurements of Polyimide/Silicon Nitride nanocomposite interphase
摘要： According to recent studies on electrical insulation systems, the nanocomposite organic/inorganic hybrid materials (NC) assure a distinct improvement of their high-temperature functioning and allow strengthening the dielectric properties of these systems. Recently it was shown that some modifications of the electrical properties such as the permittivity, dielectric breakdown and materials lifetime, were often awarded to the properties of what it is called the interphase. This interphase represents the interaction zone between the nanoparticles and the matrix and plays very often a leading part in the definition of the macroscopic properties. In this paper, Atomic Force Microscopy (AFM) is used to make, at the same time, qualitative and quantitative measurements of these interaction zones. For example, Peak Force Quantitative Nano Mechanical (PF QNM) mode, would allow to highlight the presence of the interphase by measuring mechanical properties (Young’s modulus, deformation and adhesion). As a result, this new and original study on Polyimide/Silicon Nitride (PI/Si3N4) nanocomposite confront experimental results with theoretical models.
关键词： Polyimide,PF-QNM,AFM,Nanocomposite,Si3N4 nanofillers,Interphase,Nanodielectrics
更新于2025-09-09 09:28:46
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15.1: <i>Invited Paper:</i> Bonding Spacer Technologies for Future Foldable LCDs using Ultra-Thin Polyimide Substrates
摘要： We have developed foldable LCD using ultra-thin polyimide substrates and bonding polymer spacer and successfully achieved small curvature of radius less than 2mm. We discuss the bonding spacer can suppress the deformation of plastic substrate and achieve high image quality in bending state.
关键词： Polyimide substrate,Small radius of curvature,Foldable LCD,Bending stress,Bonding spacer,Liquid crystal display
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Novel low dielectric loss polyimide film: synthesis and high frequency electrical properties
摘要： The thioether structure was introduced into the poly (N, N’- phenoxyphenyl pyromellitimide) (PMDA-ODA), owing to the extremely low dielectric loss of polyphenylene sulfide (PPS) in high frequency. Novel polyimide film containing 60% sulfide was synthesized through thermal imidization. The properties of these polyimide films morphology, thermal, dielectric characteristics and high frequency surface discharge lifetime, were studied. The films exhibited good thermal stability, having a mass loss less than 50% in decomposition temperature at 800 ?C. The phenyl sulfide containing polyimide films showed a lower dielectric loss tangent and longer lifetime in the effect high frequency high voltage surface discharge. The novel polyimide is more suitable in the insulation application of high frequency power electronic devices.
关键词： lifetime,high frequency,polyimide,phenyl sulfide,dielectric loss
更新于2025-09-09 09:28:46
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald, Germany (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Measurement of Surface Potential Distribution of Fluorinated Polyimide Film
摘要： Metal-Dielectric-Metal structure is widely applied in many pulsed power systems, such as electro-vacuum devices, high power microwave equipment and particle accelerators. This kind of composite insulation is suffered with high gradient electric field, which may result in phenomena of surface flashover across the dielectric. Corresponding surface charges and trap characteristics are important parameters, determining final flashover. This paper is focused on surface charges distribution (SCD) and trap measurement of fluorinated polyimide film, to investigate influences of fluorination on surface potential distribution. Additionally, the treatment methods of fluorination including fluorinated gas proportion and applied time have significant influences on SCD. The improvement of SCD can lead to flashover threshold improvement. These results are effective to illuminate theoretical mechanism of fluorination suppression and optimize the treatment process.
关键词： trap characteristics,polyimide film,surface potential distribution,surface fluorination
更新于2025-09-09 09:28:46