Construction of Late Transition Metal Complex on Amine-Functionalized SiO₂ and SBA-15 for L-Lactide Polymerization

Abstract

We report the in-situ synthesis of a late transition metal catalyst on amine-functionalized SBA-15 and amorphous silica and their ring opening polymerizations of L-lactide. Funtionalizations of SBA-15 and amorphous silica with N-[3-(trimethoxysilyl)propyl]-ethylenediamine (2NS) were carried out to in-situ synthesize late transition metal catalysts on the surface of nanoporous materials. FT-IR spectra indicates that the 1,2-dimethoxyethane ligand did not participate in the reaction when (DME)NiBr2 was immobilized on the amine-functionalized silica. In addition, the XPS spectrum confirmed the presence of Ni compound on the 2NS-functionalized SiO2. SBA-15/2NS/Ni and SBA-15/ 2NS/Pd catalysts showed higher conversion of PLA polymerization in comparison to SiO2/2NS/Ni and SiO2/2NS/Pd, respectively. The molecular weights of PLA produced by SBA-15/2NS/Ni or Pd were larger than those of SiO2/2NS/Ni or Pd, respectively. The effects of polymerization conditions such as the polymerization temperature, time, the catalyst amount in the feed, and the polymerization medium in L-lactide polymerization were also investigated.

Current advances in the utility of functionalized SBA mesoporous silica for developing encapsulated nanocatalysts: state of the art

“…Not only the functionalized mesoporous silica can be employed as catalysts, they can be exploited as nanoreactors for incorporation of another catalytic species such as nanoparticles, [76][77][78][79] complexes 80,81 for developing state of the art encapsulated catalysts.…”

Advances in cyclic ester ring‐opening polymerization using heterogeneous catalysts

“…By attaching 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride to the pre-calcined silica and treating the mixture with potassium tert-butoxide, a heterogeneous N-heterocyclic carbene catalyst was produced. 108 Compared with PLA generated with its homogeneous N-heterocyclic carbene counterpart, the molecular weight of PLA obtained using a supported catalyst was found to be lower, as well as the narrow molecular weight distribution. Additionally, the produced heterogeneous catalyst has slightly reduced catalytic activity than its homogeneous analog.…”

“…Furthermore, it was also found that heterogeneous systems made by directly activating SiO 2 with Al (Me) 3 or Al (OiPr) 3 104 were relatively poor initiators in contrast to ligand-tethered systems. Ko et al 108 presented an instance of how late transition metals can be immobilized. N- [3-(trimethoxysilyl) propyl]-ethylenediamine was employed to functionalize the amorphous silica and mesoporous silica SBA-15, which were then used as supports.…”

“…Ko et al 108 presented an instance of how late transition metals can be immobilized. N‐[3‐(trimethoxysilyl)propyl]‐ethylenediamine was employed to functionalize the amorphous silica and mesoporous silica SBA‐15, which were then used as supports.…”

“…Some organocatalysts were also successfully immobilized and utilized as cyclic esters ROP catalysts. By attaching 1‐methyl‐3‐(3‐trimethoxysilylpropyl) imidazolium chloride to the pre‐calcined silica and treating the mixture with potassium tert‐butoxide, a heterogeneous N‐heterocyclic carbene catalyst was produced 108 . Compared with PLA generated with its homogeneous N‐heterocyclic carbene counterpart, the molecular weight of PLA obtained using a supported catalyst was found to be lower, as well as the narrow molecular weight distribution.…”