High performance poly (urethane-imide) prepared by introducing imide blocks into the polyurethane backbone

A series of novel linear poly(urethanc-imide)s were synthesized by the reaction between isocyanate-terminated polyurethane (PU) prepolymer and amine- or anhydride-terminated oligoimide. PU prepolymer was synthesized by reacting polyethylene adipatediol of molecular weight 1000 with tolylene-2,4-diisocyanate at the molar ratio of 2:3 or 1:2. Oligoimide was synthesized front the reaction of 4,4'-(hexafluoroisopropylidene) diphthalic acid with 4,4'-oxydianiline it various molar ratios. Equimolar amounts of PU prepolymer and oligoirnide were reacted in N-methyl-2-pyrrolidone, followed by casting on glass plates and heat treatment at 100 and 150 degrees C for 1 h each to give linear poly(urethanc-imide)s as transparent yellowish brown films. Poly(urethane-imide) films with less of 30% of imide component became elastomer, and films with more than 36% imide component became plastic. The effects of end-groups Of OligOirrlide, molecular weight of oligoirnide, and molecular weight of PU prepolymer on the solvent resistance, the tensile properties, viscoelastic properties, and thermogravimetric properties of poly(urethane-imide) films were systematically examined. Solvent resistance and tensile modulus of poly(urethane-imide) films from arnine-terminated oligoimides were better than those from anhydride-terminated oligoimides. On the other hand, thermal stability and elongation at break for the poly(urethanc-imide) films front anhydride-terminated oligoimides were higher than those front amine-terminated oligoirnides. (c) 2005 Elsevier Ltd. All rights reserved.