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 degrees C) and good solubility in aprotic solvents, as well as a low melt viscosity (0.1 P at 280 degrees 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 degrees C for 1 h, a cured sample exhibited an unexpectedly higher glass transition temperature (370 degrees 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. (c) 2007 Wiley Periodicals, Inc.