Synthesis of Novel Nonisocyanate Poly(imide-urea)s from CO2-based Polyureas

Polyimides show excellent thermal stability and mechanical properties, but the high glass transition temperature (Tg) renders difficulty to their processing. To solve such a problem, herein, a series of novel poly(imide-urea)s (PIUs) were synthesized from CO2-based polyureas (PUas) with 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) and 4,4′-diaminodiphenyl ether (ODA) in the absence of isocyanate. The PIUs with adjustable thermal and mechanical properties and variable solubility were obtained by altering the molar ratio and molecular weight of CO2-based PUas. Incorporating CO2-based PUas at a 5% molar ratio could significantly lower the Tg by nearly 70 °C compared to the polyimide (based on s-BPDA and ODA), leading to a large improvement in the processing performance and simultaneously preserving the high thermal and mechanical properties of polyimide, where a tensile strength reached 146 MPa, Young's modulus was 3.0 GPa and a 10% weight loss temperature remained at 411 °C.