Neodymium-based catalysts bearing phosphate ligands NdCl3-3L; L = triethyl phosphate (TEP) or tris(2-ethylhexyl) phosphate (TEHP) were successfully synthesized. These Nd catalysts were tested for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) in the presence of various initiators (benzyl alcohol, pentaerythritol, and poly(ethylene glycol) methyl ether) to generate polymers with relatively narrow polydispersity indices (PDI = 1.22 to 1.55) and tunable molecular weights. An important result from the kinetic studies revealed that the catalyst with the sterically bulkier ligand TEHP gave a higher rate of polymerization and lower amount of the transesterified product. The livingness of this catalytic system was demonstrated by kinetic studies and by successful synthesis of the block copolymer poly(ε-caprolactone)-block-poly(L-lactide) by sequential monomer addition. The in situ NMR studies were also performed by monitoring the reaction of NdCl3-3TEP and benzyl alcohol at room temperature. The result from the mechanistic studies has indicated that the ROP reaction takes place through a coordination-insertion mechanism.

Neodymium-based catalysts NdCl3-3L (L = triethyl phosphate (TEP) or tris(2-ethylhexyl) phosphate (TEHP) for ring opening polymerization of ε-caprolactone

255th National Meeting (2018)

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