SYNTHESIS AND DIELS-ALDER POLYMERIZATION OF FURFURYLIDENE AND FURFURYL-SUBSTITUTED MALEAMIC ACIDS

The reactions of monomaleamic acid derived from an aromatic diamine with furfural afforded a novel class of furfurylidene-substituted maleamic acids 2a-2d. The latter were cyclodehydrated to yield maleimides 3a-3d which are AB-monomers for a Diels-Alder polymerization. In addition, N-furfurylmaleamic acid (4) was synthesized by reacting furfurylamine with maleic anhydride at ambient temperature. Cyclodehydration of 4 afforded N-furfurylmaleimide (5). The polymer precursors were characterized by IR and H-1-NMR spectroscopy. Their curing behavior was investigated by DTA and correlated with chemical structures. Diels-Alder polymerization of monomers occurred at the temperature range of 113-210-degrees-C. Thermal stability of monomers was evaluated by TGA and isothermal gravimetric analysis (IGA). It was shown that thermal stability of the polymer derived from maleamic acid 4 was dramatically improved upon curing at high temperatures due to the formation by dehydration of a stable aromatic structure.