Functional Polyimide Research Articles

Surface modification enabling 4.7 V Nickel-rich layered cathode with superior long-term cyclability via novel functional polyimide binders

High voltage operation of LiNi0.8Co0.1Mn0.1O2 (NCM) for high energy density lithium-ion batteries has poor cycling performance, due to the unstable cathode-electrolyte interface. Herein, two functional polyimides (PIs), one polyimide with hydroxyl group is abbreviated as PI-OH and the other polyimide with carboxyl group is abbreviated as PI-COOH, are designed to contain hydroxyl, carboxyl, trifluoromethyl and ether groups and used as cathode binder, which allows a strong hydrogen bond interaction, abundant chemical bonding sites, superior electrochemical oxidation resistance, and excellent flexibility. Experimental results reveal that both PI-OH and PI-COOH binders show the impressive efficiency on improving the cathode-electrolyte interface stability and long-term cyclability. Especially, the NCM cathode using PI-COOH binder exhibits the highest cyclability (205 mAh g−1 at 40 mA g−1 with 73% capacity retention after 100 cycles at 4.7 V), contrasting to NCM cathode with commonly-used polyvinylidene fluoride (PVDF) binder (208 mAh g−1 with 34% capacity retention). Furthermore, the fully-charged NCM cathode with PI-COOH binder releases the less heat than the NCM/PVDF cathode during high-temp treatment to 300 °C, demonstrating the superiority of polyimide binders in improving the safety of the cathode materials.

Improving of the structures and properties of functional polyimide films by direct blend method

AbstractTriphenylamine (TPA)‐based polyimides (PIs) have excellent discoloration characteristics and widely used as functional films. However, these PIs usually exhibit lower mechanical and thermal properties, and TPA units as the electron donor also weaken the optical transmittance of PIs. Utilized blending with diaminodiphenyl ether (ODA)‐based PIs, we successfully prepared the blend polyimide (BPI) films containing ODA/TPA units, to realize complementary advantages of excellent mechanical, thermal, optical, and electrochemical properties. Among them, the tensile strength of BPI‐53 film (mole ratio of TPA/ODA = 5:3) is reached up to 105.5 MPa, which is 641.9% much higher than 14.22 MPa of TPA‐PI film. Moreover, the thermal stability of BPI‐53 film is also significantly improved. T5 (temperature of 5% weight loss) can be increased to 548.26°C for BPI‐53 film, and the weight residual rate at 800°C in N2 atmosphere is increased by an addition of 4%. Besides, BPI‐53 film also has good transmittance property in district of 400–700 nm, and the variation range of transmittance under 1.0 V positive bias voltage is of 36.61%. For the electrochromics, the discoloration properties of blend polyamide acid (BPAA) dry film can be well maintained.

Highly Self-Healable Polymeric Blend Synthesized Using Polymeric Glue with Outstanding Mechanical Properties

A highly self-healable polymeric system with enhanced mechanical properties is prepared by blending conventional polyurethane (PU) with functional polyimide (PI). PU and PI synthesized in this stud...

Symmetric All-Organic Battery Containing a Dual Redox-Active Polymer as Cathode and Anode Material.

All-organic batteries are a promising sustainable energy storage technology owing to the wide availability, flexibility, and recyclability of organic/polymeric compounds. The development of all-organic or polymer batteries is still a challenge, as both electrode materials need to be carefully optimized to have a wide difference of redox potential and compatibility with the electrolyte. Herein, dual redox-active polyimides based on phenothiazine and naphthalene tetracarboxylic dianhydride units are presented. After only one optimization step, the electrodes based on these dual redox polymers can be applied simultaneously as anode and cathode in a symmetric all-organic battery. The phenothiazine functional polyimide shows two redox active voltages at around 2.5 and 3.7 V (vs. Li/Li+ ) with high discharge capacities of 160 mAh g-1 . Moreover, the symmetric full battery delivers high power density up to 1542 W kg-1 with stable cyclability for 1000 cycles. This work demonstrates an efficient strategy to develop dual redox active polymer electrodes for next generation all-polymer batteries.

Non-flammable LiNi0.8Co0.1Mn0.1O2 cathode via functional binder; stabilizing high-voltage interface and performance for safer and high-energy lithium rechargeable batteries

Demands of increased energy density and high-safety of lithium-ion and lithium metal batteries are growing for advanced electronics, electric vehicles and energy storage systems. Nickel-rich layered oxides such as LiNi0.8Co0.1Mn0.1O2 (NCM811) are appealing as promising high-capacity cathode materials. Their reversible capacity increases further by charging to higher voltages than conventional 4.2 V, which is however difficult to make because of unstable cathode-electrolyte interface and structural degradation. Herein, we report the combination of NCM811 cathode active material with non-aqueous functional polyimide binder to imparts enhanced thermal stability and highly stable interface originating from in situ building-up of surface protective polyimide layer at cathode through monodentate metal-carboxylate chemical bonds during slurry preparation, which permits to charge to 4.4 V despite in commercial electrolyte without any additive. This unique active material-binder combination not only suppresses metal-dissolution and cathode degradation and produces increased reversible capacity higher than 200 mAh g−1 but also provides unprecedented non-flammable characteristics contrary to the case of conventional binder, enabling a stable operation of higher energy and safer batteries.

53‐2: Highly Self‐healable Coating Materials with Improved Mechanical Surface Properties for Flexible Electronic Displays

A new self‐healable coating material is prepared by blending conventional polyurethane and functional polyimide. The blended coating material has outstanding self‐healing abilities and, interestingly, significantly increased surface hardness and modulus compared with polyurethane only, which is attributed to the strong supramolecular networks resulting from interactions between polyurethane and functional polyimide.

A bulky aromatic functional polyimide composite as a sensitive layer for the detection of organic compound biomarkers

A conductive polymer composite (CPC) was designed as a gas sensor for the detection of lung cancer biomarkers. A poly(ether-imide) with aromatic bulky pendant groups was synthesized and used as a CPC transducer by introducing multi-walled carbon nanotubes for the detection of acetone, toluene, methanol, ethanol and water vapor as lung cancer biomarkers. The following trend in CPC response was observed for different vapors: AR (acetone) > AR (toluene) > AR (ethanol) > AR (methanol) > AR (water). The sensing ability of the conductive polymer composite towards the above biomarkers was evaluated based on Hansen solubility parameters of the analytes. The prepared sensitive layer showed a good sensitivity against a wide range of analytes with various polarities. The good sensitivity of designed sensitive layer was attributed to the non-polar –CH3 groups besides the bulky aromatic pendant groups of the as-synthesized polymer. The aromatic pendant groups have established relatively strong attractions with the carbon nanotube (CNT) surfaces leading to the creation of significant active sites in the CNTs’ junctions. As a result of adsorption of the analyte molecules on those active sites, especially at low concentrations, the bulky aromatic groups were found much to improve the sensitivity of the prepared gas detector by affecting the electron tunneling of 3-D nano-conductive filler architecture. The experimental results illustrated that the synthesized CPC has a promising potential as a lung cancer biomarker detector.

High-performance flexible electromagnetic shielding polyimide fabric prepared by nickel-tungsten-phosphorus electroless plating

In this paper, functional polyimide (PI) fabric with high electrically conductive and electromagnetic shielding effect was prepared by nickel-tungsten-phosphorus (Ni-W-P) electroless plating. Firstly, a wave-absorbing and conductive polyaniline (PANI) layer was in-situ polymerized on the surface of fabric. Secondly, the PANI reduced the palladium ions to palladium particles acting as catalytically active sites. Finally, Ni-W-P electroless plating was initiated and formed a uniform and dense layer. The features of Ni-W-P alloy layer on PI fabric were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The thermal stability of the sample was also evaluated by thermogravimetric analysis (TGA). The results showed that the electrical conductivity was 0.08 Ω/sq and the outstanding electromagnetic shielding effectiveness (SE) could reach 103 dB. Moreover, the robust SE performance after multiple ultrasonic washing and bending tests also implied the resultant material had a great potential in the textile protection fields.

Nonvolatile Bistable Resistive Switching in Polyimide Bearing Trifluoromethyl Film

A functional polyimide (CF3 PI) was used as the active layer in our present work for electrical resistive memory device applications. Current–voltage ([Formula: see text]–[Formula: see text]) characteristics analysis on the polyimide memory devices indicates that the polyimide possesses a nonvolatile rewritable flash characteristic with an ON/OFF current ratio of about 104 at the threshold voltage of around [Formula: see text][Formula: see text]V and 3.8[Formula: see text]V. In addition, the device using the CF3 PI as the active layer reveals excellent long-term operation stability with the endurance of reading cycles up to 108 under a voltage pulse and retention times for at least 106[Formula: see text]s under constant voltage stress (1[Formula: see text]V). The conduction mechanisms are elucidated on the basis of the thermionic emission theory and filament conduction.

Electrical Bistability and Erasable Memory Effect of a Functional Polyimide Film: Synthesis and Investigation of Mechanism

A functional polyimide (PI) film, (hexafluoroisopropylidene)diphthalic anhydride–2-(9H-carbazol-9-yl)ethyl 3,5-diaminobenzoate (6FDA–DADBC), in which DADBC serves as electron donor and 6FDA as electron acceptor, was synthesized in this work. The PI has electrical bistability and the sandwich device ITO‖6FDA–DADBC–PI‖Au made by using this functional PI as the active layer has nonvolatile memory-storage properties. It can be changed between the insulating state (Off state) and the conducting state (On state) by application of potentials of approximately 0.5 V and −2.5 V, respectively, with an On/Off current ratio of approximately 102, which is suitable for use as flash memory. Mechanisms of the charge transfer occurring in the materials were investigated, and are thoroughly discussed on the basis of molecular simulation. The PI has good thermal stability up to 400°C.

Design and synthesis of polyimide – Gold nanofibers with tunable optical properties

Aromatic polyimides possess high thermal stability, flexibility, good chemical resistance, mechanical strength, enhanced dielectric properties, being thus widespread used in electronic and microelectronic industry or as a support in high temperature applications. Herein, a soluble functional polyimide with pendant phenol groups was synthesized and its potential to stabilize gold nanoparticles was highlighted by comparison with an aromatic polyimide with similar backbone but lacking the phenol units. Furthermore, composite nanofibers based on the polyimide bearing phenol units and gold nanoparticles were prepared by using an in-situ e-spinning approach. Electrostatic spinning revealed homogenous fiber formation with diameters in the range of 0.28–0.77μm for pure polyimide, whereas for gold containing polyimide beaded fiber morphologies with diameters in the range of 50–60nm were determined. A clear influence of the solution properties was measured regarding fiber diameters. Thermal treatment of the composite nanofibers yielded highly dispersed embedded metallic gold particles exhibiting diameters in the range of 9–22nm, with an increase in particle diameters by enlarging the thermal exposure time. The thermal stability of the composite nanofibers was evaluated by thermogravimetric analysis (TGA) and only a slight decrease in the decomposition temperature in comparison to the pristine polyimide-based nanofibers was observed. Finally, we investigated the effect of thermal treatment on the optical properties of the new nanofibers and we revealed the possibility of tuning the reflective characteristics of the nanofibrous surfaces in function of the annealing time.

Volatile static random access memory behavior of an aromatic polyimide bearing carbazole-tethered triphenylamine moieties

A functional polyimide (6F/CzTPA PI), 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)/ 4,4′-diamino-4″-N-carbazolyltriphenylamine (DACzTPA), was synthesized in our present work for electrical resistive memory device applications. Semiconductor parameter analysis on the polyimide memory devices indicates that the synthesized polyimide possesses a volatile static random access memory (SRAM) characteristic with an ON/OFF current ratio of about 105 at the threshold voltage of around 1.5 V and −1.8 V. In addition, the device using the 6F/CzTPA PI as the active layer reveals excellent long-term operation stability with the endurance of reading cycles up to 108 under a voltage pulse and retention times for at least 8 h under constant voltage stress (−1 V). The charge transfer mechanisms and the roles of the donor and acceptor components in the PI macromolecules associated with the electrical switching effect are elucidated on the basis of the experimental and quantum simulation results.

Nonvolatile electrical switching behavior observed in a functional polyimide thin film embedded with silver nanoparticles

In this paper, we report our works on the synthesis of a silver-nanoparticle-embedded polyimide (PI) thin film and its electrical bistability. A soluble PI, (4,4′-(hexafluoroisopropylidene) diphthalic anhydride/4,4′-oxydianiline (6FDA/ODA), where the 6FDA part serves as an effective electron-accepting moiety, was synthesized in our current work as the polymer matrix. Silver nanoparticles (Ag NPs) with diameters less than 7 nm were subsequently generated in situ in the parent PI film via ultraviolet (UV) reduction of the (1,1,1-trifluoro-2,4-pentadionato) silver(I) complex (AgTFA) previously incorporated in the matrix. Electrical characterization results on the sandwiched device (ITO|PI (6FDA/ODA)/silver nanohybrid film|Au) indicate that the nanohybrid material possesses electrical bistability and the device exhibits two accessible conductivity states, which can be reversibly switched from the low-conductivity state to the high-conductivity state with an ON/OFF current ratio of about 102. The device with the PI (6FDA/ODA)/silver nanohybrid film as the active layer shows nonvolatile memory behavior. The high-conductivity state and the low-conductivity state of the device can be sustained after the removal of the applied voltage. Mechanisms regarding the charge transfer in the nanohybrid material were discussed.

Novel high‐performance polymer memory devices containing (OMe)2tetraphenyl‐p‐phenylenediamine moieties

AbstractThe functional polyimide (OMe)2TPPA‐6FPI (PI) and the polyamide (OMe)2TPPA‐6FPA (PA) consisting of electron‐donating N,N′‐bis(4‐aminophenyl)‐N,N′‐di(4‐methoxylphenyl)1,4‐phenylenediamine [(OMe)2TPPA‐diamine] for memory application were prepared in this study. These polyimide and polyamide memory devices were fabricated with the sandwich configuration of indium tin oxide (ITO)/polymer/Al, and could be switched from the initial low‐conductivity (OFF) state to the high‐conductivity (ON) state with high ON/OFF current ratios of 107 and 109, respectively. PI exhibited dynamic random access memory (DRAM) performance, whereas PA showed static random access memory (SRAM) behavior. To get more insight into the memory behaviors of these two different types of polymer memory devices, molecular simulation on the basic unit was carried out. Furthermore, the differences of highest occupied molecular orbital (HOMO) energy level, lowest unoccupied molecular orbital (LUMO) charge density isosurfaces, dipole moment, and linkage conformation between PI and PA were found to affect the volatile memory behavior. Both polymer memory devices revealed excellent stability with long operation time of 104 s at continuous applied voltage of ‐2 V. The effect of polymer thickness on the volatile memory behavior of PA was also investigated in this study. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Nonvolatile memory effect of a functional polyimide containing ferrocene as the electroactive moiety

A functional polyimide, hexafluoroisopropyl bis(phthalic dianhydride)/4-(bis(4-aminophenyl) methyl)phenol grafted with ferrocene, was synthesized. Electrical characterization results indicate that the sandwiched devices using our synthesized polyimide as the active layer possess electrical bistability and exhibit nonvolatile memory behavior with an ON/OFF current ratio of about 103. Molecular orbitals and electronic properties are investigated by molecular simulation and cyclic voltammetry characterization. The charge transfer mechanisms in the OFF and ON states of the memory device were reasonably interpreted by using the thermionic emission and space-charge-limited-current model, respectively.

Dynamic Random Access Memory Effect and Memory Device Derived from a Functional Polyimide Containing Electron Donor‐Acceptor Pairs in the Main Chain

A functional polyimide, hexafluoroisopropyl bis(phthalic dianhydride)/3,6-diaminocarbazole (6FDA/DAC), in which DAC serves as electron donor and 6FDA as electron acceptor, has been synthesized in our present work. Electrical characterization results on the sandwiched polyimide memory device (ITO/Thin polyimide Layer/Au) indicate that the polyimide possesses electrical bistability and the device exhibits two accessible conductivity states, which can be reversibly switched from the low-conductivity (OFF) state to the high-conductivity (ON) state with an ON/OFF current ratio of about 10(4). Different from the widely reported write-once-read-many-times (WORM) effects, the device with the 6FDA/DAC polyimide as the active layer shows dynamic random access memory (DRAM) behavior. The ON state of the device was lost immediately after removal of the applied voltage, while by applying a constant bias (e.g., 3 V) the ON state can be electrically sustained. The roles of donor and acceptor components in the polyimide main chain were elucidated through molecular simulation.

Volatile Electrical Switching and Static Random Access Memory Effect in a Functional Polyimide Containing Oxadiazole Moieties

A solution-processable functional polyimide, P(BPPO)-PI, containing oxadiazole moieties (electron donors) and phthalimide moieties (electron acceptors) was synthesized. A switching device, based on a solution-cast thin film of P(BPPO)-PI sandwiched between an indium−tin oxide (ITO) bottom electrode and an Al top electrode, exhibits two accessible conductivity states and can be switched from the low-conductivity (OFF) state to the high-conductivity (ON) state when swept positively or negatively, with an ON/OFF current ratio on the order of 1 × 104. The device exhibits ON state “remanence”, with the ON state retainable for a period of about 4 min after turning off the power. The ON state can be electrically sustained either by a refreshing voltage pulse of −1 V or by a continuous bias of −1 V. The “remanent” but volatile nature of the ON state and the ability to write, read, and sustain the electrical states with bias are characteristic features observed in a static random access memory (SRAM). The mechanis...

Volatile electrical switching in a functional polyimide containing electron-donor and -acceptor moieties

A solution-processable functional polyimide (PYTPA-PI), containing triphenylamine-substituted diphenylpyridine moieties (PYTPA, electron donors) and phthalimide moieties (PI, electron acceptors), was synthesized. The copolymer exhibits a high glass transition temperature of 342 °C. A switching device, based on a solution-cast thin film of PYTPA-PI sandwiched between an indium-tin oxide (ITO) bottom electrode and an Al top electrode, exhibits two accessible conductivity states and can be switched from the low-conductivity (OFF) state to the high-conductivity (ON) state, with an ON/OFF current ratio of more than 103, at the threshold voltage of about 2.7 V. The ON state is volatile and relaxes readily to the OFF state. However, it can be electrically sustained by a refreshing voltage pulse of 2 V. The ON state can also be reset to the initial OFF state by a reverse bias of −0.9 V. The ability to write, erase, read, and refresh the electrical states fulfills the functionality of a dynamic random access memory. The electronic transitions and transport mechanisms associated with the memory effect were elucidated from molecular simulation. In comparison with that of other functional polyimides, the electrical switching performance in PYTPA-PI illustrates the possibility of tuning memory properties in imide polymers via molecular design and synthesis.

Development and Application of Functional Polyimide Particles

ポリイミド微粒子は優れた耐熱性,機械的性質,耐薬品性を有する。そのため長期的に安定した性能を維持する。また,微粒子表面への官能基の導入や機能性材料による修飾が可能である。今後,ポリイミド微粒子は各種先端分野のキーマテリアルになると期待できる。本稿では,ポリイミド微粒子の調製方法と応用技術について紹介する。

Synthesis and Dynamic Random Access Memory Behavior of a Functional Polyimide

The device under testing was a plastic dynamic random access memory based on a donor-functionalized polyimide (TP6F-PI), which exhibited the ability to write, read, erase, and refresh the electrical states. The device had an ON/OFF current ratio up to 105, promising minimal misreading error. Both the on and off states were stable under a constant voltage stress of 1 V and survived up to 108 read cycles at 1 V.