Phosphorus‐containing polyurethans

Phosphorus‐containing polyurethans of the formula magnified image were prepared by interfacial polymerization of 1,4‐butanebischloroformate and p‐xylylene‐α, α‐bischloroformate with bis(m‐aminophenyl)alkylphosphine oxides. The polymers had number average molecular weights up to 8600. A test of the stability to alkali of one of the polymers (RCH3, X1,4‐C6H4) showed it to be as resistant as nonphosphorus analogs, and a film of this polymer exhibited self‐extinguishing properties. Thermal degradation of the phosphorus polymers, which began at approximately 230°C, occurred by an initial first‐order process, releasing chiefly carbon dioxide. The energies of activation for the maximum rates of weight loss were 31–37 kcal/mole.