Studies on organosoluble polyimides based on a series of new asymmetric and symmetric dianhydrides: Structure/solubility and thermal property relationships

Redox-active polyimides for energy conversion and storage: from synthesis to application

As the demand for next-generation electronics is increasing, organic and polymer-based semiconductors are in the spotlight as suitable materials owing to their tailorable structures along with flexible properties. Especially, polyimide (PI) has been widely utilised in electronics because of its outstanding mechanical and thermal properties and chemical resistance originating from its crystallinity, conjugated structure and π-π interactions. PI has recently been receiving more attention in the energy storage and conversion fields due to its unique redox activity and charge transfer complex structure. In this review, we focus on the design of PI structures with improved electrochemical and photocatalytic activities for use as redox-active materials in photo- and electrocatalysts, batteries and supercapacitors. We anticipate that this review will offer insight into the utilisation of redox-active PI-based polymeric materials for the development of future electronics.

Highly optical transparency and thermally stable polyimides containing pyridine and phenyl pendant

In order to obtain highly optical transparency polyimides, two novel aromatic diamine monomers containing pyridine and kinky structures, 1,1-bis[4-(5-amino-2-pyridinoxy)phenyl]diphenylmethane (BAPDBP) and 1,1-bis[4-(5-amino-2-pyridinoxy)phenyl]-1-phenylethane (BAPDAP), were designed and synthesized. Polyimides based on BAPDBP, BAPDAP, 2,2-bis[4-(5-amino-2-pyridinoxy)phenyl]propane (BAPDP) with various commercial dianhydrides were prepared for comparison and structure-property relationships study. The structures of the polyimides were characterized by Fourier transform infrared (FT-IR) spectrometer, wide-angle X-ray diffractograms (XRD) and elemental analysis. Film properties including solubility, optical transparency, water uptake, thermal and mechanical properties were also evaluated. The introduction of pyridine and kinky structure into the backbones that polyimides presented good optical properties with 91-97% transparent at 500 nm and a low cut-off wavelength at 353-398 nm. Moreover, phenyl pendant groups of the polyimides showed high glass transition temperatures (Tg ) in the range of 257-281 °C. These results suggest that the incorporating pyridine, kinky and bulky substituents to polymer backbone can improve the optical transparency effectively without sacrificing the thermal properties.

Influence of terminating triamine by phthalic anhydride on polyimides’ properties

In this study, hyperbranched polyimides were prepared from 2,6-bis(4-aminophenyl)-4-(4-(4-aminophenoxy)phenyl)pyridine (BAAP) and commercial dianhydrides by strictly controlling the reaction conditions. Polyimides with phthalimide pendants were also prepared to study the influence mechanisms of terminating BAAP by phthalic anhydride (PA) on polyimides’ properties. Fourier transform infrared and proton nuclear magnetic resonance spectroscopies were utilized to observe the chemical structures of the hyperbranched polyimides. The influence of terminating BAAP by PA on polyimides’ properties was studied by comparing the two series of polyimides. All the polyimide samples held completely amorphous structures and possessed excellent solubility and thermal stability. Terminating BAAP by PA decreased the d-spacing values of the obtained polyimides and slightly weakened their solubility and thermal stability.

Study of thermal decomposition kinetics for polyimides based on 2,6-bis(4-aminophenyl)-4-(4-(4-aminophenoxy) phenyl) pyridine

This study reports on the preparation and thermal decomposition kinetics of a polyimide (PI) with phthalimide pendant (PI-1) and an analogous hyperbranched PI (PI-2). PI-1 was synthesized from 2,6-bis(4-aminophenyl)-4-(4-(4-aminophenoxy) phenyl) pyridine (BAAP) and 4,4′-(hexa-fluoroisopropylidene) diphthalic anhydride using a simple method with BAAP terminated by phthalic anhydride. The morphology of the PI structures was examined using X-ray diffraction. The thermal decomposition processes of the PIs were then studied according to a two-stage method using thermogravimetric analysis. The results indicated that both PIs exhibited excellent thermal stability, with a decomposition pattern of 5% mass loss beyond 508°C and 10% beyond 529°C. The two PIs exhibited similar levels of thermal stability in the first decomposition stage, but PI-1 exhibited higher stability in the second stage. The results indicate that PIs into which phthalimide pendants have been introduced retain their thermal stability in the first stage of decomposition and demonstrate enhanced thermal stability in the second stage.