Phthalonitrile resins, as a type of high performance thermosetting materials, have been widely studied in the past decades, due to the outstanding combination of properties such as thermal and oxidative-thermal stability, low water uptake and flame-retardance.1 However, the polymerization of the neat resin is extremely sluggish, thus limiting their application.2 On the other hand, phenylethynyl end-capped thermosetting resins have also received much attention.3 The derived polymers exhibit unique thermal and dimensional stability, excellent chemical resistance and mechanical properties, which offer promise for advanced composites application.However, the intensively curing exothermic effect of the phenylethynyl-based resins was an unbeneficial characteristic for fabrication of thick composite sections.In this study, the model compound with both phthalonitrile and phenylethynyl groups 3PN3PEODPA, the phthalonitrile or phenylethynyl end-capped imide compounds (3PNOPDA or 3PEODPA) were synthesized from 4, 4-oxydiphthalic anhydride (ODPA) with 4-(3-aminophenoxy) phthalonitrile or 3-phenylethynyl aniline by imidization of chemical dehydration (SCHEME 1), with an aim to combine their own curing characteristics, which may offer a new type of resin systems with adjustable processability and tailored properties.The rheological behavior of the imide compounds was studied by dynamic oscillation employing a TA Instruments AR-2000ex rheometer in conjunction with an environmental testing chamber for temperature control.In FIGURE 1, storage modulus is shown as a function of time at 330 ℃ for the three imide compounds.All of the samples exhibited a melt viscosity of less than 0.1 Pa.s at 330 ℃.When held at 330 ℃ for a period of time, the melt viscosity of the compound 3PN3PEODPA with both phenylethynyl and phthalonitrile groups increased, while that of 3PNODPA is very low, and maintained at about 0.1 Pa.s for a relatively long time.Interestingly,through a comparative study of the rheological behavior of 3PEODPA and 3PN3PEODPA, we could find that the trend of thermal polymerization rate of 3PN3PEODPA slowed down significantly compared with the neat compound 3PEODPA.The results also revealed that there is a moderate large process window, which is helpful in the fabrication of large size composite sections.These results offer promise for seeking new approach to design high performance thermosetting materials.