ANIONIC SYNTHESIS OF POLY(URETHANE-G-ACRYLONITRILE)

High molecular weight poly(ester-urethane) based on diphenyl methane-4,4′-diisocyanate (MDI), PU1, and also on toluene diisocyanate (TD1), PU2, have been metallated using sodium hydride in N,N-dimethylformamide, (DMF). Metallation was confirmed by coupling samples of metallated PU1 and PU2 with methyl iodide and the use of infra-red, and n.m.r. G.p.c. studies indicated that an increase in the percentage of metallation at about 0°C in DMF caused a decrease in the stability of the soluble metallated backbone polymer and was accompanied by degradation. An increase in temperature from 0° to 100°C of a 15% metallated polyurethane sample in DMF increased the extent of degradation. At 0°C, polymers with a degree of metallation of less than 50% were relatively stable. At about 0°C in DMF, acrylonitrile was successfully grafted by anionic polymerization following metallation of PU1 and the graft copolymers were readily separated by fractionation from small amounts of the homopolymer, polyacrylonitrile. The graft copolymers were characterized by micro-analysis, solubility measurements, infra-red spectroscopy and viscometry. The vinyl monomers styrene, methyl methacrylate and vinyl acetate, and the cyclic monomers ethylene oxide, propylene oxide, N-methyl-2-pyrrolidone and hexamethylcyclotrisiloxane, could not be grafted anionically to the metallated polyurethane based on MDI. © 1979.