GM-ME (4.73 g, 0.01 mol) and isophorone diisocyanate (1.11 g,
0.005 mol) were dissolved in 20 g toluene. A solution of dibutyltin
dilaurate (0.63 g, 0.1 mmol) as catalyst in 10 g toluene was added
dropwise to the above solution at 60 C. The mixture was kept
stirring for 5 h. Then white powder of GM-ME-IPDI was obtained
after the removal of solvent by rotary evaporation under reduced
pressure at 70 C and dried in vacuum at 70 C for 8 h.