Poly‐2‐oxazolidones: Preparation and characterization

Poly‐2‐oxazolidones were synthesized by the 1,3‐cycloaddition of bisglycidyl ethers to diisocyanates with the use of N,N‐dimethylformamide and lithium chloride as solvent and catalyst, respectively. A variety of arylene and alkylene diisocyanates and coreactant bisepoxides were used in the polymer‐forming reaction. The polymers, obtained in high yield, were generally soluble in methylene dichloride, chloroform, N,N‐dimethylformamide, and dimethyl sulfoxide. They had intrinsie viscosities up to 0.42 dl/g and could be cast into films. In several cases molecular weights were determined by vapor pressure osmometry. The poly‐2‐oxazolidone based upon 1,6‐hexamethylene diisocyanate and the bisglycidyl ether of isopropylidene diphenol gave the highest molecular weight. Confirmation that the base unit of the polymers contains the 2‐oxazolidone ring was obtained by elemental analysis, infrared and NMR spectroscopy. The poly‐2‐oxazolidones synthesized were found to be amorphous by x‐ray diffraction. Thermogravimetric analyses indicated that a majority of the poly‐2‐oxazolidones were stable in dry air up to 300°C. In a number of cases Tg's were also determined by using differential scanning calorimetry.