One of the most interesting polymer structures is the cyclic structure. Various physical and biological properties of cyclic polyesters are different from their linear analogs. For example, linear comb polymers move through the pores easier than the cyclic comb polymers having the same MWs. Thus, if a cyclic polymer is used in drug delivery, the drug will stay in the body longer than the linear polymer, leading to better efficiency of treatment. Herein, new catalytic systems have been developed. Synthesis and characterization of tin complexes containing Schiff’s base ligands have been carried out. The catalytic activities of these complexes towards the ring-opening polymerizations of L-lactide (L-LA) and ε-caprolactone (ε-CL) were investigated. The tin(II) complexes containing Schiff’s base ligands, with different alkoxy side chain lengths, were synthesized by reacting Sn[N(SiMe3)2]2 with the corresponding ligands. Results from ESI mass spectrometer of the shorter side chain ligand revealed that, for a short time, the polymers existed as a mixture of linear and cyclic forms. Over longer times, the polymerization was allowed to undergo intramolecular transesterification leading to cyclic polymers. For polymerizations with a longer side chain ligand, a mixture of linear and cyclic polymers was observed.

Synthesis and characterization of cyclic polyester: Effect of alkoxy side chains on Shiff's base ligand of tin(II) complexes

253rd National Meeting (2017)

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