An anhydride monomer containing ether oxide bridge,7-oxa-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic anhydride (ONA),was successfully synthesized by Diels-Alder reaction of furan and maleic anhydride.The ONA was also studied as an end-cap for the polymerization of monomer reactant(PMR) type polyimides.Three molecular weight levels of the ONA end-capped PMR resins were evaluated.The effects of process conditions of these novel PMR resins on thermal and mechanical properties were investigated.It was demonstrated that the imidized prepolymers using the end-cap have good processability,and the cured polyimide specimens exhibited good thermal stability.The initial decomposition temperature, T_d(ca.580℃) and glass transition temperature,T_g(330℃) of the novel resin(PI-20),prepared under optimum process conditions,compare favorably with the T_d(ca.620℃) and T_g(ca.348℃) of the state-of-the-art resin(PI’-20),respectively. An anhydride monomer containing ether oxide bridge, 7-oxa-bicyclo [2,2,1] hept-5-ene-2,3-dicarboxylic anhydride (ONA), was synthesized by Diels-Alder reaction of furan and maleic anhydride. The ONA was also studied as an end-cap for the polymerization of monomer reactant (PMR) type polyimides. Thih molecular weight levels of the ONA end-capped PMR resins were evaluated.The effects of process conditions of these novel PMR resins on thermal and mechanical properties were investigated. It was demonstrated that the imidized prepolymers using the end-cap have good processability, and the cured polyimide specimens exhibit good thermal stability. The initial decomposition temperature, T_d (ca.580 ° C) and glass transition temperature, T_g ( 330 ° C) of the novel resin (PI-20), prepared under optimum process conditions, compare favorably with the T_d (ca.620 ° C) and T_g (ca.348 ° C) of the state-of- ’-20), respectively.