Design and synthesis of organosoluble and transparent polyimides containing bulky substituents and noncoplanar structures

A new diamine monomer, 3,3′‐diisopropyl‐4,4′‐diaminophenyl‐4″‐phenyltouene, was designed, synthesized, and then polymerized with five commercial dianhydrides to obtain a series of novel polyimides via a one‐step method. The obtained polymers showed excellent solubility in most common solvents, even in low‐boiling solvents, such as chloroform, dichloromethane, and tetrahydrofuran. They exhibited a high thermal stability with the glass‐transition temperature in the range 262–318°C and 10% weight loss temperatures in the range 464–488°C under a nitrogen atmospheres. Meanwhile, these polymer films also displayed a high optical transparency with a cutoff wavelength in the range 305–365 nm; prominent mechanical properties with a tensile strength of 65.6–94.9 MPa, a Young's modulus of 1.6–2.8 GPa, and an elongation at break of 9.3–13.7%; a low dielectric constant in the range of 2.91–3.18 at 1 MHz; and an outstanding hydrophobicity with a contact angle above 90.6°. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43266.