Titanium and Aluminum complexes for ring-opening polymerization of cyclic Esters

Name: Kanokon Upitak

LCSH: Kasetsart University -- Theses. M.S. (Chemistry) 2020

Classification :.LCCS: QD305.A2

LCSH: Kasetsart University. -- Department of Chemistry -- Theses

LCSH: Esters

LCSH: Cyclic compounds

LCSH: Titanium

LCSH: Aluminum

LCSH: Polymerization

Abstract: This thesis consists of two parts. In the first part, a series of titanium complexes supported by pyrrolylaldiminate ligands (1–6) were successfully synthesized and characterized by 1H and 13C NMR spectroscopy, elemental analysis, high resolution mass spectroscopy and X-ray diffraction crystallography (for complex 2). Their catalysis in the ring-opening polymerization (ROP) of raclactide (rac-LA), ε-caprolactone (ε-CL), γ-substituted-ε-caprolactones (γ-methyl-εcaprolactone, γ-ethyl-ε-caprolactone and γ-phenyl-ε-caprolactone) were reported. All complexes (1–6) were active initiators toward the ring-opening polymerization, and the polymerizations were well-controlled and living. Kinetic studies for rac-LA and ε-CL polymerization revealed first-order kinetics in monomer and the kinetic rate constants agreed well with those obtained from the COPASI fitting program. Complex 5 with adamantyl substituted showed the highest catalytic activities for both rac-LA and ε-CL polymerizations. Titanium complexes (1–6) produced atactic PLAs with the Pm values in the range of 0.53–0.58. Among the γ-substituted-εcaprolactones polymerizations, the polymerization of γ-phenyl-ε-caprolactone was faster than those of other two monomers. End-group analysis by 1H NMR spectroscopy indicated that the ring-opening polymerization proceeded through a coordination insertion mechanism. In the second part, two aluminum isopropoxide complexes bearing bis(pyrrolidene) Schiff base and Salen (N,N’-bis(salicylaldimine)-1,2- ethylenediamine) ligands (complexes 8 and 11) were successfully synthesized and characterized. Both complexes were efficient catalysts for the ROP of dioxanone (DX) and 3-methyl-dioxanone (3-MeDX). However, they were not active initiators for the polymerization of 3-ethyl-dioxanone (3-EtDX). Complex 8 displayed higher catalytic activity for the ROP of both dioxanone and 3-methyl-dioxanone than complex 11. The ROP of 3-MeDX was slower than that of DX because the thermodynamic driving force of 3-MeDX was considerably less than DX. For DX polymerization, the decrease of percent conversion and molar mass were observed after the reaction passed through a maximum conversion, suggesting the depolymerization.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Pimpa Hormnirun

Role: Thesis Advisor

Name: Pitak Chuawong

Role: Thesis CO-Advisor

Name: Tanin Nanok

Role: Thesis CO-Advisor

Created: 2020

Modified: 2025-07-24

Issued: 2025-07-24

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2563/kanokon-upi-all.pdf

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Chemistry

Grantor: Kasetsart University

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