Abstract: An improved process for preparing an aromatic polyanhydride is disclosed. The aromatic polyanhydride is prepared by reacting an aromatic dicarboxylic acid with an anhydride to form an anhydride prepolymer, isolating and purifying the prepolymer, and subjecting the prepolymer to melt polycondensation conditions. The improvement specifically relates to the purification of the acid so it is essentially free of impurities before it is reacted with the anhydride.The polymers prepared from the improved process have higher molecular weights than the molecular weights achieved from the prior art processes, and exhibit outstanding thermal stability and mechanical properties. This combination of properties allows the aromatic polyanhydrides to be melt processed to prepare numerous devices.

Abstract: Crosslinked copolymers of monomeric aminosaccharides such as aminoglycosidic antibiotics, e.g. neomycin, or of polymeric aminosaccharides, e.g., chitosan, with dialdehydes are useful antihypercholesterolemic agents due to their ability to bind with bile acids. These copolymers are insoluble in acidic solutions but are swellable to at least about 2.times. their original weight.

Abstract: Carboranylmethylene-substituted cyclophosphazenes which can be thermally polymerized into carboranylmethylene-substituted phosphazene polymers, useful as thermally stable coatings and, due to the characteristics of these polymers in acting as a ligand for transition metals, metallocarboranylmethylene phosphazene polymers which can act as immobilized catalyst systems, and are electrically conductive and superconductive.

Abstract: Carboranyl-substituted polyphosphazenes are prepared by heat polymerizing a carboranyl halocyclophosphazene at 250.degree. C. for about 120 hours in the absence of oxygen and moisture. The cyclophosphazene is obtained by allowing a lithium carborane, e.g. the reaction product of methyl-o-carborane with n-butyllithium in ethyl ether, to react with e.g. hexachlorocyclotriphosphazene at ambient temperatures and in anhydrous conditions. For greater stability in the presence of moisture, the chlorine substituents of the polymer are then replaced by aryloxy or alkoxy groups, such as CF.sub.3 CH.sub.2 O--.The new substantially inorganic polymers are thermally stable materials which produce a high char yield when exposed to extreme temperatures, and can thus serve to insulate less heat and fire resistant substances.

Abstract: Polydihalophosphazenes, e.g. --N.dbd.P(Cl).sub.2 ].sub.n, are allowed to react at ambient temperatures for at least one hour with a lithium carborane in a suitable inert solvent. The remaining chlorine substituents of the carboranyl polyphosphazene are then replaced with aryloxy or alkoxy groups to enhance moisture resistance. The polymers give a high char yield when exposed to extreme heat and flame and can be used as insulation.