Synthesis and Characterization of an Alicyclic Acid Anhydride Containing Four Stereoisomers and the Derived Polyamideimides Using Diisocyanates.

An alicyclic acid anhydride containing four stereoisomers, racemic (1S,2R,3R,4R,5R)‐bicyclo[2.2.2]octane‐2,3,5‐tricarboxylic acid‐2,3‐anhydride (7a+7a′) and racemic (1S,2S,3S,4R,5R)‐bicyclo[2.2.2]octane‐2,3,5‐tricarboxylic acid‐2,3‐anhydride (7b+7b′) (BOTA), is synthesized using phthalic anhydride as the starting material. The chemical structures of the products in each step are fully characterized by nuclear magnetic resonance (NMR) spectroscopy, gas chromatography–mass spectrometry (GC–MS), elemental analysis, and single‐crystal X‐ray diffraction. The polycondensation process involving BOTA and several diisocyanates is applied to prepare polyamideimides (PAIs). Furthermore, PAI‐Xs are prepared using methylene diphenyl diisocyanate (MDI) and various mole ratios of BOTA and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA). PAI‐Xs exhibit good solubility in organic solvents such as dimethyl sulfoxide (DMSO), N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAc), γ‐butyrolactone (GBL), N,N‐dimethylformamide (DMF), and m‐cresol at room temperature. They can form flexible films with low coefficients of thermal expansion (CTE) (51–70 ppm °C−1) and high glass transition temperatures (Tg) (222–272 °C). They also demonstrate high transparency with transmittance at 500 nm (T500 nm) ranging from 77.2% to 82.5%. BOTA can be a significant building block in PAI synthesis, offering an alternative to 1,2,4‐trimellitic anhydride (TMA). [ABSTRACT FROM AUTHOR]