MULTIDIMENSIONAL BENZOBISOXAZOLE RIGID-ROD POLYMERS .1. PREPARATION AND CHARACTERIZATION

Two- and three-dimensional rigid-rod polymers containing benzobisoxazo le structures were prepared through the polycondensation in polyphosph oric acid of 4-[5-amino-6-hydroxybenzoxazol-2-yl]benzoic acid (ABA) wi th trimesic acid and 1,3,5,7-tetrakis(4-carboxylatophenyl) adamantane, respectively. Thermal properties of the polymers were determined by d ifferential scanning calorimetry, thermogravimetric/mass spectral anal ysis, and isothermal aging studies. The multidimensional polymers exhi bited lower solution viscosities and lower thermooxidative stabilities than the one-dimensional polymer generated by the homopolymerization of ABA under identical reaction conditions. (C) 1997 John Wiley & Sons , Inc.