Construction of late transition metal complex on amine-functionalized SiO2 and SBA-15 for L-lactide polymerization

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.