New poly(ether benzoxazole)s containing xanthene cardo groups

Abstract

A series of poly(ether benzoxazole)s (PEBOs) containing xanthene cardo groups were prepared via direct one-step condensation polymerization in poly(phosphoric acid/phosphorus pentoxide solution from 9,9-bis[4-(4-carboxyphenoxy)phenyl]xanthene and various bis(o-aminophenol)s. The resulting PEBOs with inherent viscosities of 0.87–1.08 dL g⁻¹ were amorphous and exhibited glass transition temperatures in the range of 245–320°C. These new PEBOs exhibited improved solubility and could be processable from solution. Additionally, the obtained PEBOs showed excellent thermal stability, and did not show a significant weight loss up to 500°C in air or nitrogen, and the temperatures at 10% weight loss were in the range of 533–590°C in nitrogen and 508–570°C in air, with char yields more than 50% at 800°C in nitrogen. All the PEBOs formed strong and flexible films with tensile strengths of 53–80 MPa, tensile moduli of 2.3–2.6 GPa, and elongations at break of 3.2–3.7%.