Exogenous Ligand Assisted Rare-earth Complexes: Catalyst Design, Applications in Ring-Opening Polymerization and Reaction Kinetics

Dong, Xiang

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Year:: 2022
Contributor:: Dong, Xiang (creator); Robinson, Jerome (Advisor); Chen, Ou (Reader); Zimmt, Matthew (Reader); Brown University. Department of Chemistry (sponsor)
Genre:: theses
Subject:: Homogeneous catalysis; Chemical kinetics; Chemistry, Inorganic; Polymer chemistry; Rare earth metals
Extent:: xvi, 199 p.

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Abstract:: Complexes of rare-earth elements (REs, Sc, Y, La-Lu) are among the most successful catalysts for ring-opening polymerization (ROP) of lactones. However, there are gaps in synthesizing the polymers with both high efficiency and good steric selectivity. Our studies provided a novel way of constructing RE catalyst and tuning its catalytic performance by introducing exogenous ligands [phosphine oxides or lutidine-oxides (LO)]. We applied this catalytic system on the ROP of rac-β-butyrolactone (rac-BBL), which usually displays relatively low reactivity among lactone monomers and challenges in polymerization with high iso-tacticity (Pm ≥ 0.80) and got unprecedent success in both high reactivity (TOF up to 1,900 /h) and good iso-selectivity (Pm up to 0.82). Furthermore, the critical side reaction were systematically examined that significantly affected distribution of molecular weights of macromolecular product and reaction rate. In the study of raction kinetics, a method of track evolution of active catalytic species was developed and applied to quantatively determine kinetic parameters of the primary propagation and the coupling side reaction. These results may direct further developments of this exogenous ligand assisted RE catalytic system.
Notes:: Thesis (Ph. D.)--Brown University, 2022

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Citation

Dong, Xiang, "Exogenous Ligand Assisted Rare-earth Complexes: Catalyst Design, Applications in Ring-Opening Polymerization and Reaction Kinetics" (2022). Chemistry Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:dfy4vpt7/

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Chemistry Theses and Dissertations

Theses and Dissertations for the Chemistry department.
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