A method of making an isocyanato terminated precursor for polyurethane is disclosed. The method comprises heating an isocyanate containing about two or more isocyanato groups per molecule at a temperature of up to 80 degrees Celsius and at a pressure of about 1 atmosphere. The method further comprises mixing a modified vegetable oil comprising about two or more hydroxyl groups per molecule with the isocyanate at a molar equivalent ratio of at least 2:1 isocyanate to vegetable oil for a predetermined time period to form the isocyanato terminated precursor.