| 总结: | <p>This Thesis describes the activity and mechanism of alkaline earth organohydroborate, tetrahydroborate and alkoxide catalysts for the ring-opening polymerisation (ROP) of cyclic esters including <em>rac</em>-, L-, D- and <em>meso</em>-lactide (LA), and <em>rac</em>-β-butyrolactone (<em>rac</em>-BBL).</p> <p><b>Chapter One</b> introduces cyclic esters and general mechanisms for their ROP to give polyesters. Living and immortal ROP, an overview of stereocontrolled ROP, and determination of polylactide (PLA) stereosequences are given. Various techniques for polymer characterisations are also described.</p> <p><b>Chapter Two</b> describes the activity and mechanism of heavy alkaline earth organohydroborate complexes for the ROP of LA. The synthesis and characterisation of alkaline earth alkoxide complexes serving as model species are also described, together with their activities for the ROP of LA.</p> <p><b>Chapter Three</b> describes the activity and mechanism of a cyclic organohydroborate calcium complex for the ROP of LA. The role of borinic esters as chain transfer agents in the ROP of <em>rac</em>-LA is also discussed.</p> <p><b>Chapter Four</b> describes the activity and mechanism of heavy alkaline earth tetrahydroborate complexes for the ROP of LA. The immortal ROP of rac-LA using heavy alkaline earth alkoxide complexes and borate esters as chain transfer agents is discussed.</p> <p><b>Chapter Five</b> describes the activity and mechanism of alkaline earth organohydroborate, tetrahydroborate and alkoxide complexes for the ROP of <em>rac</em>-BBL.</p> <p><b>Chapter Six</b> presents experimental procedures and characterising data for new complexes reported.</p>
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