Abstract
Society is currently reliant on non–renewable fossil fuels and petrochemicalderivatives. With global population increasing, resulting in escalating demands on
both energy and materials, these resources are rapidly diminishing and a drastic,
responsive transition to a more sustainable world is required. Chemistry is at the
forefront of these global challenges and recently, a number of contemporary areas of chemistry research have seen a resurgence such as: the use of Fe for catalysis, CO2chemical transformations and the development of alternative biopolymers. Chapter 1 attempts to give a brief introduction into these concepts and the research aims.
In Chapter 2, a range of Fe(III) complexes were synthesised and characterised using a range of techniques. This included both a range of Fe(III)–salalen–chloride
complexes and air–stable Fe(III)–acetate complexes, comprising of salalen, salan and salen frameworks.
In Chapter 3, these Fe(III) complexes were assessed as active initiators for the
controlled ring opening polymerisation (ROP) of rac–lactide (rac–LA) to form the
alternative, biopolymer poly(lactic acid) (PLA). Fe(3)Cl was an effective initiator and observed a moderate isotactic bias (Pm = 0.75–0.80). Batch kinetics were conducted and the observed bimodality on the GPC chromatograms was scrutinised. In Chapter 4, the Fe(III) complexes were applied as catalysts to the coupling of CO2 with cyclohexene oxide (CHO) to form the cis–cyclohexene carbonate (cis–CHC) product exclusively. Fe(13)OAc was observed to be the most active catalyst and was applied to further terminal epoxides. UV–Vis spectroscopy was used to investigate the observed colour change in the reaction mixtures.
In Chapter 5, the application of these Fe(III) complexes was extended to the ring
opening copolymerisation of phthalic anhydride (PA) and CHO with no need for co–catalyst. It was discovered from control reactions that the ligands were active as organocatalysts with salophen 17 observing the highest molecular weight polyester with 29100 gmol-1. The addition of a third monomer, rac–LA, was attempted for terpolymerisation, but two separate polymer species were formed. Lastly, the degradation of PLA to methyl lactate (Me–LA) was investigated.
| Date of Award | 17 Jan 2022 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Matthew Jones (Supervisor) & Andrew Johnson (Supervisor) |