(D, L)-Lactide (LA) was first polymerized with one component of rare earth catalysts [Nd(naph)(3), Nd(oct)(3), Nd(O-iPr)(3), Nd(AcAc)(3), Y(AcAc)(3), Sm(AcAc)(3), Er(AcAc)(3))] respectively in solution and in melt sta...(D, L)-Lactide (LA) was first polymerized with one component of rare earth catalysts [Nd(naph)(3), Nd(oct)(3), Nd(O-iPr)(3), Nd(AcAc)(3), Y(AcAc)(3), Sm(AcAc)(3), Er(AcAc)(3))] respectively in solution and in melt state. The effects of [Cat]/[La] molar ratio, solvents, polymerization time, temperature, various rare earth Elements and ligands were investigated in detail. The results showed that both the conversion of polymerization and the molecular weight (MW) of poly (D, L-Lactide) (PLA) in melt polymerization are higher than that in solution polymerization, but the polymerization rate in melt was lower than in solution. The molecular weight distribution (MWD) of PLA is broader with increasing temperature. X-ray study indicated that PLA obtained by Nd(AcAc)(3) in melt polymerization is an amorphous polymer.展开更多
The neodymium complex supported on styrene-maleic anhydride copolymer (SMA·Nd) has been prepared for the first time and found to be a highly effective catalyst for the polymerization of styrene. The SMA·Nd p...The neodymium complex supported on styrene-maleic anhydride copolymer (SMA·Nd) has been prepared for the first time and found to be a highly effective catalyst for the polymerization of styrene. The SMA·Nd polymeric complex is characterized by IR and its catalytic activity, and the polymerization features have been investigated in comparison with that of the conventional Ziegler-Natta catalysts. When [Nd]=1×10^(-3) mol/L, [M]=5mol/L, Al/Nd=170(mol ratio) and CCl_4/Nd=50(mol ratio), the polymerization conversion of styrene gets to 51.6% in six hours, and the catalytic activity reaches 1852 gPS/gNd, which is much higher than that of conventional rare earth catalysts. The polymerization reaction has an induction period and shows some characteristics of chain polymerization. The polymerization rate is the first order with respect to the concentration of styrene monomer. Addition of FeCl_3 does not suppress the polymerization.展开更多
The neodymium complexes with crosslinked polystyrene containing -CH2SH and -CH2SOCH3 groups, P-CH2SH . NdCl3 and P-CH2SOCH3. NdCl3, were prepared. P-CH2SH . NdCl3 shows no catalytic activity for butadiene polymerizati...The neodymium complexes with crosslinked polystyrene containing -CH2SH and -CH2SOCH3 groups, P-CH2SH . NdCl3 and P-CH2SOCH3. NdCl3, were prepared. P-CH2SH . NdCl3 shows no catalytic activity for butadiene polymerization, while P-CH2SOCH3. NdCl3 can catalyze the polymerization of butadiene. The content of cis-1,4-polybutadiene is more than 95%.展开更多
Polymerization of N-Octadecylmaleimide was studied using rare earth coordination catalysts in toluene.The dependence of polymerization on molar ratio of catalyst components,different rare earth elements,catalyst conce...Polymerization of N-Octadecylmaleimide was studied using rare earth coordination catalysts in toluene.The dependence of polymerization on molar ratio of catalyst components,different rare earth elements,catalyst concentration,monomer concentration,polymerization time and polymerization temperature was investigated in detail.The results showed that the rare earth catalysts were favorable catalysts for the polymerization of N-Octadecylmaleimide.A suitable condition for the polymerization was [La(P507)3]= 1×10-2?mol·L-1;（[Al（i-Bu）3]）=8.0×(10-2?mol·L-1);[NODMI]=5.0×(10-1?mol·L-1);60℃;6?h.Characterization of the polymer obtained showed that polymerization of N-Octadecylmaleimide proceeded via opening the double bond in the monomer molecules.The heat-resistant property of the polymer was investigated primarily.The polymer showed excellent thermal stability.The thermal decomposition of the polymer proceeded via a one-step reaction and no substantial weight loss was observed below 350℃.The initial decomposition temperature(Tini) was 360℃,the maximum decomposition temperature(Tmax) was 441℃,and the residual weight at 500℃ was about（3.4?wt%）.展开更多
基金This work was supported by the National Natural Science Foundation of China and the Laboratory of Rare-earth Chemistry and Physics,Changchun Institute of Applied Chemistry,Academia Sinica
文摘(D, L)-Lactide (LA) was first polymerized with one component of rare earth catalysts [Nd(naph)(3), Nd(oct)(3), Nd(O-iPr)(3), Nd(AcAc)(3), Y(AcAc)(3), Sm(AcAc)(3), Er(AcAc)(3))] respectively in solution and in melt state. The effects of [Cat]/[La] molar ratio, solvents, polymerization time, temperature, various rare earth Elements and ligands were investigated in detail. The results showed that both the conversion of polymerization and the molecular weight (MW) of poly (D, L-Lactide) (PLA) in melt polymerization are higher than that in solution polymerization, but the polymerization rate in melt was lower than in solution. The molecular weight distribution (MWD) of PLA is broader with increasing temperature. X-ray study indicated that PLA obtained by Nd(AcAc)(3) in melt polymerization is an amorphous polymer.
文摘The neodymium complex supported on styrene-maleic anhydride copolymer (SMA·Nd) has been prepared for the first time and found to be a highly effective catalyst for the polymerization of styrene. The SMA·Nd polymeric complex is characterized by IR and its catalytic activity, and the polymerization features have been investigated in comparison with that of the conventional Ziegler-Natta catalysts. When [Nd]=1×10^(-3) mol/L, [M]=5mol/L, Al/Nd=170(mol ratio) and CCl_4/Nd=50(mol ratio), the polymerization conversion of styrene gets to 51.6% in six hours, and the catalytic activity reaches 1852 gPS/gNd, which is much higher than that of conventional rare earth catalysts. The polymerization reaction has an induction period and shows some characteristics of chain polymerization. The polymerization rate is the first order with respect to the concentration of styrene monomer. Addition of FeCl_3 does not suppress the polymerization.
文摘The neodymium complexes with crosslinked polystyrene containing -CH2SH and -CH2SOCH3 groups, P-CH2SH . NdCl3 and P-CH2SOCH3. NdCl3, were prepared. P-CH2SH . NdCl3 shows no catalytic activity for butadiene polymerization, while P-CH2SOCH3. NdCl3 can catalyze the polymerization of butadiene. The content of cis-1,4-polybutadiene is more than 95%.
文摘Polymerization of N-Octadecylmaleimide was studied using rare earth coordination catalysts in toluene.The dependence of polymerization on molar ratio of catalyst components,different rare earth elements,catalyst concentration,monomer concentration,polymerization time and polymerization temperature was investigated in detail.The results showed that the rare earth catalysts were favorable catalysts for the polymerization of N-Octadecylmaleimide.A suitable condition for the polymerization was [La(P507)3]= 1×10-2?mol·L-1;（[Al（i-Bu）3]）=8.0×(10-2?mol·L-1);[NODMI]=5.0×(10-1?mol·L-1);60℃;6?h.Characterization of the polymer obtained showed that polymerization of N-Octadecylmaleimide proceeded via opening the double bond in the monomer molecules.The heat-resistant property of the polymer was investigated primarily.The polymer showed excellent thermal stability.The thermal decomposition of the polymer proceeded via a one-step reaction and no substantial weight loss was observed below 350℃.The initial decomposition temperature(Tini) was 360℃,the maximum decomposition temperature(Tmax) was 441℃,and the residual weight at 500℃ was about（3.4?wt%）.
