A Novel Polymerization Process of Poly(4,4'-oxydiphenylenepyromellitamic acid)

Preparation of Polyimides by Using Mixtures of Tetrahydrofuran and Methanol and Their Properties

“…The tensile modulus and strength and also the thermal stability are slightly higher for PI based on PAA (NMP). Echigo 3 found the values of tensile modulus and strength 286 MPa and 17 MPa, respectively. The properties characterizing the chain packing are compared in Table II.…”

“…1 These monomers were also frequently employed in studies devoted to PI synthesis using THF/MeOH mixed solvent. [3][4][5] Concentrations of solutions of polyimide precursors (PAA) in NMP for commercial and research purposes usually range from 10 to 15 wt%. Echigo 3,4 describes the preparation of a 15 wt% PAA solution based on the above mentioned monomers using THF/MeOH mixtures with composition ratio 4:1 (w/w).…”

“…10 The role of the THF/MeOH mixed solvent in the synthesis of PAA(THF/MeOH) is not clear. It was found, 3 that the reaction of the pyromellitic acid dimethyl ester with ODA in THF/MeOH did not practically proceed. To elucidate this role -at least partly-the properties of mixed solvent were investigated in dependence on its composition.…”

“…2 From this point of view the preparation of PAA in the tetrahydrofuran/methanol mixed solvent (THF/MeOH) appears to be promising. [3][4][5][6][7][8] However, in our preliminary tests we were unable to reproduce the preparation of 15 wt% solutions of PAA based on pyromellitic dianhydride (PMDA) and 4, 4 -oxydianiline (ODA) in THF/MeOH with component ratio 4:1 (w/w) as described by Echigo et al 3,4 The reaction conditions of the preparation of PAA solutions (based on PMDA and ODA) in THF/MeOH mixtures and the transformation of the resulting PAA into PI are studied in this work. The properties of final films are compared with those prepared by using NMP as the solvent.…”

Preparation and properties of polyimides and polyamide-imides from diisocyanates

“…4 They are conventionally prepared by reaction of a diamine and a dianhydride in a polar solvent to provide a poly(amic acid) that, on subsequent heating, loses water and forms a polyimide. Research and study in this field are growing, including the use of a novel solvent system for polyimide synthesis 5 and a high pressure synthesis of polyimides. 6 In another important method, diisocyanates are reacted with different reactants.…”