Effects on Physical Properties of Polyimide Urethanes by Introduction of Pyromellitic Imide Bonds and Addition of Fullerene

Abstract

After fullerene C ₆₀ was dissolved in o-tolidine diisocyanate (TODI), isocyanate-terminated prepolymers were synthesized by reaction of the C ₆₀ /TODI solution and poly(oxy-tetramethylene)glycol 2000 (PTMG). The prescribed C ₆₀ contents for polyimide urethane elastomers (PIUEs) were varied at 0~1,000 ppm. In the next step, the prepolymers were reacted with chain extender 1,4-butanediol (BD), additionally in the other systems, composites of PIUEs and fullerene were prepared by replacing a part of BD with pyromellitic dianhydride (PMDA). In this way, the pyromellitic imide bonds were introduced into the hard segments of PIUEs. These composites were evaluated by tensile properties, dynamic mechanical analysis, differential scanning calorimetry and scanning probe microscopy. It was found that the tensile strength has a greater effect on the physical properties at break than the modulus of low elongation region, and the effect of fullerene and pyromellitic imide bonds greatly increases the tensile strength. Moreover, from higher-order structure analysis, as reported previously, it was clarified that both the addition of fullerene and the introduction of pyromellitic imide bonds promoted the formation of micro phase separation of PIUEs. As a result, it was found that a stronger and finer hard segment domains were formed by synergistic effect of both.