Polymerization of n-Hexyl Isocyanate with Rare Earth Catalyst Composed of Nd(P_(204))3/Al(i-Bu)_3

摘要

Rare earth catalyst system:lanthanide phosphonate/tri-i-butyl aluminum (Nd(P_(204))_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(P_(204))_3 and Nd(P_(507))_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=39.6xl0~4,Mv=67.2xl0~4),molecular weight distribution (MWD=2.44) and yield (82.7%) under the moderate reaction conditions:catalyst concentration [Nd]=6.65xl0~(-2)mol/L,Al/Nd=10 molar ratio,[HNCO]/[Nd]=100 molar ratio,at -10deg C for l0h in bulk.Relatively high reaction temperature (-10 deg C) is the most distinct virtue.The IR and NMR analyses show that the polymer obtained is not polyether but polyisocyanate.