Pyridine and Bipyridine End-Functionalized Polylactide: Synthesis and Catalytic Applications

Poly(lactic acid) (PLA) was functionalized at the polymer chain end with nitrogen-containing aromatic groups such as pyridine and 2,2?-bipyridine by means of Sn(II)-catalyzed ring-opening polymerization. The obtained macroligands along with the corresponding stereocomplexes were suitable ligands to stabilize Pd(II) and Pd-nanoparticles (NPs). The nature of the introduced terminal group plays a key role in the successful stabilization of small Pd-NPs in the course of the catalytic oxidation and reduction reactions, favorably influencing hence the catalytic activity and chemoselectivity of the catalytic reactions. The PLA-based polymer backbone proved to be resistant against transesterification reactions under real catalytic conditions and to significantly increase its thermal stability in the presence of Pd-NPs.