Polyurethane-60 is the complex polymer made by first reacting saturated methylene diphenyldiisocyanate (SMDI), dimethyl aminopropylamine (DMAPA), isopropylidenediphenoxypropanol, and dimethylcarbonate-1,6-hexanediol to form a prepolymer, followed by dispersion in water with dimethylethanolamine and subsequent chain extension with ethylenediamine.