Homopolyimides containing both benzimidazole and benzoxazole with highT_gand low coefficient of thermal expansion

Abstract

A pair of isomer diamines containing both benzimidazole and benzoxazole and derived homopolyimides were synthesized for the first time. Due to rich rigid and linear benzoazole units, as well as the strong intermolecular interactions from the hydrogen bonding and the charge transfer complexation (CTC), the obtained polyimides (PIs) exhibited outstanding thermal properties, including high thermal weight loss temperature (T d5% = 540-561 C), high glass transition temperature (T g = 392-421 C), and low coefficient of thermal expansion (CTE = 1.3-20.9 ppm/ C). In addition, the obtained PIs also showed ideal mechanical properties (T S = 189-240 MPa, T M = 4.1-5.0 GPa and E B = 2.9%-4.7%). These potential novel PI films with high T g and low CTE were expected to be applied to next generation of flexible display substrate material.

Synthesis and properties of transparent poly(ester‐amide‐imide)s from tert‐butylhydroquinone bis(trimellitate anhydride) and p‐phthaloyl chloride

“…The T g s of the PEsAI‐a‐ x series were in the range 231–272 °C and the T g s of the PEsAI‐b‐ x series were in the range 235–301 °C. According to the T g values of the two series of PEsAI films, T g increased with increase of the TPC content, which was attributed to the increase in the number of hydrogen bonds and the increase in the interaction between molecular chains 40 . Typical DMA plots are presented in Fig.…”

“…The UV–visible absorption spectra of the films were measured on a Lambda 950 UV/Vis/NIR spectrophotometer. Wide‐angle X‐ray diffraction (WAXD) measurement of the films was conducted on a Bruker D8 Advance diffractometer 40 …”

Largely Enhanced High-Frequency Insulation Performances of Polyimide by Incorporating Siloxane-Based Fillers

“…The PI matrix is synthesized from diamine and dianhydride, where diamine donates electrons and dianhydride accepts electrons. This behavior is also called charge transfer complexation, which affects the arrangement of PI macromolecular chains . Under the irradiation of UV–vis light, electrons will be excited, and they will transit between different orbital energy levels.…”

Ultra‐highTgand ultra‐low coefficient of thermal expansion polyimide films based on hydrogen bond interaction

“…To realize the application of PI thin film in flexible substrate, PI substrate firstly needs a high T g > 450°C to avoid film deformation and to tolerate the 300–500°C processing temperature of LTPS–TFT. Secondly, a low CTE (0–5 ppm K −1 ) of PI is required to match the CTE of inorganic components in the device to avoid peeling off from each other during substrate layer stripping; peeling off is caused by temperature changes during device processing 8–12 . Unfortunately, the performance of commercial PI films, such as Kapton H® and Upilex S®, cannot meet the abovementioned requirement for flexible OLED substrates.…”

“…Secondly, a low CTE (0-5 ppm K À1 ) of PI is required to match the CTE of inorganic components in the device to avoid peeling off from each other during substrate layer stripping; peeling off is caused by temperature changes during device processing. [8][9][10][11][12] Unfortunately, the performance of commercial PI films, such as Kapton H ® and Upilex S ® , cannot meet the abovementioned requirement for flexible OLED substrates. Therefore, further improvement of T g and reduction of CTE have become hot research topics in the field of PI film materials.…”