Design and synthesis of a tribranched phenylethynyl‐terminated aryl ether compound and its use as a reactive diluent for PETI‐5

In this study, a tribranched, phenylethynyl‐terminated aryl ether compound (Tri‐PE‐PAEK) was synthesized. This novel star‐shaped compound exhibits a good combination of properties, such as a low melting temperature (252 °C) and good solubility in aprotic solvents, as well as a low melt viscosity (0.1 P at 280 °C). All these advantages make it a good candidate material for modern processing techniques such as resin infusion and resin transfer molding, which are the most favorable methodologies for current economical manufacturing of polymer matrix/carbon fiber composites. Furthermore, after undergoing thermal curing to yield a network at 370 °C for 1 h, a cured sample exhibited an unexpectedly higher glass transition temperature (370 °C), storage modulus retention above the glass transition temperature, and good thermal stability. In addition, this compound can be used as a reactive diluent for phenylethynyl‐terminated imide oligomer, which has the molecular weight of 5000 g/mol (PETI‐5) to reduce its viscosity and lower the minimum temperature of the minimum viscosity. Meanwhile, the toughness of a cured blended resin can be greatly increased with the addition of just 10% Tri‐PE‐PAEK to PETI‐5. Further loading levels of Tri‐PE‐PAEK in the blending would lead to a higher storage modulus and a higher mechanical strength without compromising the thermal stability.