Polymerization of n-Hexyl Isocyanate with Rare Earth Catalyst Composed of Nd(P204)3/Al(i-Bu)3

Summary Rare earth catalyst system: lanthanide phosphonate/tri-i-butyl aluminum (Nd(P₂₀₄)₃/Al(i-Bu)₃) has been found for the first time as a novel catalyst for the polymerization of n-hexyl isocyanate (HNCO). Nd(P₂₀₄)₃ and Nd(P₅₀₇)₃ are the commercial names of neodymium 2-ethylhexyl phosphonates, their formulas are shown in table 1. The catalyst can be prepared easily by mixing Nd(P₂₀₄)₃ and Al(i-Bu)₃. The effects of catalyst, solvent, reaction temperature and time on the polymerization of HNCO were studied. The obtained poly (n-hexyl isocyanate) (PHNCO) was characterized by GPC, FT-IR, ¹H-NMR and TGA. The resulting PHNCO had molecular weight (Mn=39.6×10⁴, Mv=67.2×10⁴), molecular weight distribution (MWD=2.44) and yield (82.7%) under the moderate reaction conditions: catalyst concentration Nd]=6.65×10^-2mol/L, Al/Nd=10 molar ratio, HNCO]/Nd]=100 molar ratio, at -10^oC for 10h in bulk. Relatively high reaction temperature (-10^oC) is the most distinct virtue. The IR and NMR analyses show that the polymer obtained is not polyether but polyisocyanate.