Polyamide-imide Films Research Articles

Synthesis and characterization of high Tg and colorless polyamide-imide films derived from amide-containing diamines with different trifluoromethyl substitution

Four new diamines (3TFDABA, 2TFDABA, 22TFDABA and TFAPTA) were successfully synthesized to investigate the effect of different trifluoromethyl (CF3) substitution position on poly(amide-imide)s (PAIs) properties. High-performance PAIs were prepared from high-temperature polycondensation of these diamines with 6FDA dianhydride. All the PAI films exhibited good heat resistance with glass-transition temperatures (Tgs) of 311–392 °C, good 5% weight loss temperatures (Td5%s) of 480–510 °C in nitrogen, and excellent optical transparency with T450 ranging from 52% to 84%. According to the monomer structural design, a high heat resistant and colorless poly(amide-imide) film (PAI-2-6FDA), with excellent optical properties (T450 of 82%), outstanding thermal properties (Td5% of 499 °C and Tg of 392 °C), and good mechanical properties (tensile strength of 123 MPa, tensile modulus of 4.4 GPa) was achieved. A comprehensive structure-to-property relationship study revealed that the CF3 in ortho-position of the amino group effectively inhibited the rotation between imide ring and benzene, thus improved the heat resistance of the film. Moreover, it could also weaken the generation of charge transfer complexes through strong electron-withdrawing ability, which is beneficial for the synthesis of colorless polyimides.

Effects of rigid end-capped groups on the structure and properties of colorless polyamide-imide films

In this work, we use 2-aminobenzimidazole and 2-aminobenzoxazole to end-cap colorless polymer, PAITFDB-TPC-6FDA, in order to investigate methods for reducing the CTE value of products and their effects on other properties. Results show that, as the ratio of 2-aminobenzimidazole to the raw material, diamine TFDB, increases from 0:100 to 2:99, the CTE value of products gradually decreases from 20.0 to 12.9 ppm/K (a decrease of 36%). Nevertheless, the CTE value of products rebounds as the dosage of the end-capped groups exceeds this ratio. Among all the products obtained, PAI-1M film has the best overall properties: its CTE is 12.9 ppm/K, Td5 is 518 ℃, Tg is 366 ℃, TS is 191 MPa, T430 is 85.1%, WA is 85.4% and CA is 0.8%. The two end-capped groups are of highly linear and rigid structures. They also help to enhance the hydrogen bonding between molecules, resulting in a decrease in d-spacing values. The results of molecular configuration simulation and calculation indicate that, using 2-aminobenzimidazole to end-cap the chains of PAI molecules is beneficial for suppressing the formation of the charge-transfer complexes (CTCs), and thereby offsetting impacts of the reduced molecular chain spacing on the transparency of films. Based on these two influencing factors, we confidently conclude that linear and rigid end-capped groups can effectively improve the dimensional stability and mechanical properties of PAI films without damaging their optical properties.

Highly tough, colorless, transparent polyamide-imide films from one reaction vessel without purification

Highly tough, colorless, transparent polyamide-imide films from one reaction vessel without purification

High efficiency synthesis of temperature resistant polyamideimide resin with branched structure using microreactor

Polyamideimide (PAI) resins have a wide range of applications. It is significant to explore novel and efficient synthesis methods. This paper describes a method for the rapid synthesis of branched PAIs in a microreactor using 4,4-methylenediphenyl diisocyanate (MDI) and 1,2,4-benzoic acid anhydride (TMA) as substrates. The isocyanate group reacts with the amide bond to build the branched structure. A high molar ratio of substrate helps to form more branched structures. High molar ratios also lead to high molecular weight products with narrow distribution, where the number average molecular weight of PAI-1.35 is as high as 1828.14 kg/mol and the molecular weight distribution index is only 1.09. Some oligomers are present in the products obtained at low molar ratios, which affect the mechanical and thermal properties of the products. Curing with epoxy resin can form a bulk structure and eliminate the effect of oligomers. The PAI films obtained after curing have excellent mechanical and thermal properties.

Mechanically Robust and Transparent Polyamideimide Films via Consecutive Polycondensation, Amidation, Acid Removal, and Bluing Agent Addition

Mechanically Robust and Transparent Polyamideimide Films via Consecutive Polycondensation, Amidation, Acid Removal, and Bluing Agent Addition

Ultraflexible polyamide-imide films with simultaneously improved thermal conductive and mechanical properties: Design of assembled well-oriented boron nitride nanosheets

The highly thermally conductive yet electrically insulating polymeric materials are exhibiting tremendous potential for thermal management materials. However, the practical application of these materials is restrained by the limited thermal conductivity (TC) and deterioration of mechanical properties. In this work, an ultraflexible polyamide-imide (PAI) film with a sandwich-like structure composed with assembled well-oriented functionalized boron nitride nanosheets (FBN) by facile layer-by-layer solution-coating strategy is constructed. The design of the layered structure and highly oriented arrangement of interconnected FBN (Herman's orientation parameter ƒ up to 0.847) endows the obtained PAI composite film with super-flexibility, ultrahigh in-plane thermal conductivity (λ//), superior thermal transfer capability (ΔTmax = 24.4 °C) and excellent electrical insulation performance. The PBP composite film reaches an ultrahigh λ//of 45.7 W m−1 K−1 with only 23 wt% FBN loading and exhibits a remarkable TC enhancement factor over 23 because of the more continuous phonon transfer networks that constructed by interconnected well-oriented FBN which could effectively suppress the phonon scattering. Furthermore, the mechanical properties of the layered composite film (PB4P) exhibit noteworthy enhancement compared with uniform PBN composite film, in which the tensile strength is increased by 110% and toughness enhancement is 329%. Meaningfully, our fabrication strategy has the advantage of simplicity and adaptability for commercial amplification. The composite film developed in this work provides a promising prospect for the thermal management system of modern power electronic devices.

High-performance polyamide-imide films: Effect of functionalization degree of BN nanosheets

Chemical functionalization of boron nitride (BN) is necessary to improve the dispersion of the BN as well as interface compatibility within polymer matrix to enhance the properties of their composites. However, the degree of BN functionalization needs to be considered comprehensively to fully highlight the advantages. In the present work, a polyamide-imide (PAI) film with a parallel arrangement structure and designed functionalization of BN nanosheets by self-assembly technique is constructed. The design of optimum functionalization and defect control of the functionalized BN nanosheets (f-BNNSs) provides this flexible PAI/f-BNNSs composite film exhibits highly in-plane thermal conductivity, superior electrically insulating and improved mechanical properties. The thermal conductivity of the PAI/f-BNNSs film had an impressive improvement of 167%, from 5.06 W m−1 K−1 of PAI/BN film to 13.5 W m−1 K−1 of PAI/f-BNNSs film (PP1W3) at a low filler content of only 9 wt%. More importantly, systematic research was carried out in terms of the degree of functionalization, the quantities of defect of f-BNNSs and the performance of the composite films, which further revealed the mechanism of the thermal conductivity improvement of PAI/f-BNNSs composite films. This research provides significant guidance for the design of composite materials with excellent thermal conductivity based on the functionalization of low dimensional fillers, ensuring its application in the thermal management of high-power density electronic devices.

Synthesis and properties of transparent random and multi-block polyamide-imide films with high modulus and low CTE

Two new series of transparent polyamide-imides (PAIs) with high modulus and low coefficient of thermal expansion (CTE) were prepared by random or block copolymerization of 4,4′-biphthalic dianhydride (BPDA) and p-phthaloyl chloride (TPC) with 2,2′-bis(trifluoromethyl)benzidine (TFDB). These series of PAIs displayed low CTE of 16–42 ppm/K, good mechanical properties with high tensile modulus ranging from 4.9 to 6.6 GPa, tensile strengths of 112–170 MPa and elongations at break of 2.0–5.4%, as well as high transparency with transmittances at 500 nm (T500nm) of 84–87%, which was greatly affected by the feed ratio of monomer BPDA & TPC, and the block length caused by block polymerization. The block copolymer PAI-3-B1 presented the best comprehensive performance with high transparency (T500nm) of 87%, low CTE of 16 ppm/K and high tensile modulus of 6.1 GPa.

Transparent polyamide-imide films with high Tg and low coefficient of thermal expansion: Design and synthesis

Two series of optically transparent polyamide-imides (PAIs) were prepared by copolymerization of trimelletic acid chloride (TMAc), p-phthaloyl chloride (TPC), 2,2′-bis(trifluoromethyl)-[1,1′-biphenyl]-4,4′-diamine (TFDB) and 4,4’-(9-fluorenylidene) diamine (FDA). These series of PAIs displayed high glass transition temperatures (Tgs) ranging from 340 to 441 °C, 5% weight loss temperatures (T5%s) in nitrogen with 459–505 °C, and low coefficient of thermal expansion (CTE) of 21–56 ppm/K, which greatly affected by the feed ratio of rigid TPC units and cardo diamine in the polymer main chain. The transmittances at 500 nm (T500nm) of the PAI films were found in the range of 70.0–87.7%, All polymers demonstrated good organosolubility and mechanical properties with tensile strengths of 77–146 MPa, tensile moduli of 2.9–5.8 GPa and elongations at break of 2.9–8.2%. PAI-7-8 presented the best combination of high Tg of 401 °C and high tensile modulus of 5.0 GPa, low CTE value of 24 ppm/K, and high transparency (T500nm) of 87.2%.

High-performance polyamide-imide films and electrospun aligned nanofibers from an amide-containing diamine

Polyamide-imides (PAIs) are highly desired in many applications because of their superior thermal and mechanical properties. In this work, PAI was prepared from an amide-containing diamine and dianhydride by polycondensation and thermal treatment. Both PAI films and aligned electrospun nanofibers (ANFs) were fabricated. FT-IR was used to determine the structure formation of PAI at different annealing temperatures. DSC and TGA were used to evaluate the thermal properties of PAI, while tensile test was applied to evaluate the mechanical properties of PAI films and ANFs. The results indicated that the PAI possessed both outstanding thermal stability and mechanical properties, which provide opportunities for applications in gas separation, high temperature filtration, reinforcement, etc.

Preparation of solution-processable colorless polyamide-imides with extremely low thermal expansion coefficients through an in-situ silylation method for potential space optical applications

AbstractSeveral tough and flexible fluorinated polyamide-imide films were prepared from trimellitic anhydride chloride and 2,2′-bis(trifluoromethyl)benzidine through a facile one-pot in-situ silylation method. By incorporating fluorinated side groups, the solubility of the prepared polyamide-imide was greatly enhanced. Meanwhile, due to their linear chain configuration and the existence of hydrogen bonding, the prepared polyamide-imide films revealed high tensile strength, high tensile modulus, high glass transition temperature (Tg) and most interestingly, very low coefficient of thermal expansion (CTE) of 11 ppm/°C. Copolymerization with pyromellitic dianhydride (PMDA) led to an extremely low CTE of 4 ppm/°C which should be among the lowest values available for soluble polyamide-imides. The optical homogeneity and stress homogeneity of the obtained polyamide-imide films were also tested. After non-contact with substance and thermal treatment at 300°C, they revealed a better optical homogeneity and stress homogeneity than that of the commercially available Kapton polyimide (PI) films, with a PV value of 0.915 λ and RMS value of 0.163 λ. Thus, these colorless and soluble polyamide-imide films simultaneously possessing promising optical imaging performance are good candidates as novel diffractive membrane optical system architectures.

Enhanced gas barrier and mechanical properties in organoclay reinforced multi-layer poly(amide-imide) nanocomposite film

Multifunctional single and triple-layer films exhibiting flexibility, enhanced modulus and gas barrier properties were developed using a soluble polyamide-imide (PAI) in dimethylacetamide (DMAc) with ammonium-modified montmorillonite (MMT, Cloisite 30B) mineral clay. The drying behavior and associated anisotropy development were determined real-time, using a newly developed real-time measurement system. Out-of-plane birefringence development takes place earlier for thinner neat samples caused primarily by increased depletion rate of solvent. Addition of organoclay content resulted in a decrease in evaporation rate of solvent due to planar orientation of well exfoliated nanoplatelets as shown by TEM images and WAXS. This is in agreement with the out-of-plane anisotropy development observed during drying. Beyond a critical solid wt%, out-of-plane birefringence started to increase earlier with organoclay addition. In the case of multi-layer organoclay reinforced PAI films, the drying behavior of each individual layer was tracked and a complementary drying model is proposed. Planar orientation of nanoplatelets resulted in high helium-barrier properties.

Preparation and Properties of Thermoplastic Polyamide-imide and Polyurea-amide-imide/Copper Foil Composites

Polyamide-imide (PAI) and polyurea-amide-imide (PUAI) resins were polymerized from five reactants: 4,4'-oxydianiline, 4-nitrobenzoyl chloride, 4,4'-diphenylmethane diisocyanate, 1,2,4,5-benzenetetracarboxylic dianhydride, and 3,3'-4,4'-benzophenone tetracarboxylic dianhydride. Their chemical structures were characterized using elemental analysis, FTIR and 1H NMR spectroscopy. Their thermal properties, adhesive properties, electrical properties, heat resistance, and chemical resistance were studied. The experimental results show that the glass transition temperatures of PAI and PUAI films occurred respectively at 360 °C and 229 °C, and the 10% weight loss occurred respectively at approximately 481 °C and 420 °C. The optimal hot-press conditions for PAI/copper foil (CU) composite were 380°C and 4.90 MPa, whereas those for PUAI/copper foil (CU) composites were 250 °C and 4.90 MPa. Values of the peel strength, dielectric constant, and dissipation factor were obtained and the peel strength was re-measured after a thermal stability test. The chemical resistance tests showed that the peel strength retention values of the PAI/CU and PUAI/CU composites were respectively more than 95% and more than 94% after immersing in 10% H2SO4 solution at 70 °C for 1 h.

Polyamide-imide polymer thin films for integrated optics

The applicability of a polyamide-imide (PAI) polymer to thin film optical applications was investigated. The polymer preparation and spin characteristics are described in detail. The films exhibited good adhesion to silicon, glass, and benzocyclobutene polymer. The refractive index was measured in the near infrared region. To demonstrate feasibility for devices, features were plasma etched into PAI films. Oversized inverted rib waveguides were also fabricated using PAI as a core material, and losses as low as 0.2 dB/cm were measured at 830 nm. Polyamide-imide is a highly robust and stable polymer, similar to the widely used polyimides, and is an excellent candidate material for integrated optics applications.

Polyamide-imide polymer thin films for integrated optics

The applicability of a polyamide-imide (PAI) polymer to thin film optical applications was investigated. The polymer preparation and spin characteristics are described in detail. The films exhibited good adhesion to silicon, glass, and benzocyclobutene polymer. The refractive index was measured in the near infrared region. To demonstrate feasibility for devices, features were plasma etched into PAI films. Oversized inverted rib waveguides were also fabricated using PAI as a core material, and losses as low as 0.2 dB/cm were measured at 830 nm. Polyamide-imide is a highly robust and stable polymer, similar to the widely used polyimides, and is an excellent candidate material for integrated optics applications.

ゾルーゲル法によるガラスーポリアミドイミド複合体の絶縁破壊特性と熱劣化

ゾルーゲル法によるガラスーポリアミドイミド複合体の絶縁破壊特性と熱劣化

Composite conduction in ion-implanted polymers

The temperature dependence of the dc conductivity for polyamide-imide films, implanted with 50 keV As ions to different fluences, has been studied. Our high-resolution data reveal a two-component conductivity that depends on both one-dimensional variable range hopping (VRH) and three-dimensional VRH. For low fluence levels (5×1015 ions/cm2), the one-dimensional VRH is dominant while at higher fluences (1×1017 ions/cm2), the three-dimensional VRH dominates. These materials become highly disordered and form hard carbon materials along the ion track. The conductivity may be explained by 1D VRH along the ion track at low fluences while at higher fluences, regions of carbon rich material form three-dimensional structures where 3D VRH exists. This rather simple model and its composite conductivity can explain the exact curvature of the temperature dependent conductivity, while single VRH models and percolation models cannot.

Synthesis and characterization of polyamide‐imides

AbstractA series of thermally stable, tough, linear polyimides containing amide linkages was prepared. The new polyamide‐imides were synthesized by reacting a group of isomers of diaminobenzanilide (DABA) with various dianhydrides, such as 4,4′‐oxydiphthalic anhydride (ODPA), 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), and 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). The resulting polyamide‐acids were thermally or chemically converted to the polyamide‐imide (PAI). Twelve polyimides were synthesized from unsubstituted and N‐methyl substituted amide diamines and their properties were compared with previously made polyamide‐imides and the polyimide LARC‐TPI. These polyimides exhibited high inherent viscosities and glass transition temperatures. They were made into tough, flexible films of which some showed good thermal stability and resistance to organic solvents. Overall, the mechanical properties of the PAI films were comparable to those of LARC‐TPI with the 4,4′‐systems exhibiting exceptional properties and crystallinity. These materials have potential as high temperature films, coatings and fibers, as well as molding and laminating resins.

High electrical field conduction in polymers under pressure

Abstract Electrical conductivity of Polyamide-imide films was measured from 1 to 400 bars, for temperatures ranging from 35 °C to 70 °C and for d.c. electrical field varying from 0.5 to 4 MV/cm. The increasing of the conductivity with pressure can be explained by the presence of ions in the polymer.

Water sorption in polyamide–imide films and its effect on dielectric loss

AbstractWater sorption and diffusion has been measured in polyamide–imide over a range of temperature and relative humidities. The results are compared to those obtained on Kapton and discussed in terms of chemical differences between these two materials. Changes in dielectric loss during hydrothermal aging under 85°C and 85% RH have been measured. These changes are correlated to the water sorption kinetics.