While petrochemical products continue to have a strong environmental and political impact, interest in producing degradable plastics from renewable sources has been intense and many examples have been reported. Since its discovery by Carothers in 1932, poly(lactic acid) (PLA) has represented an environmental ideal of a stable and strong plastic which is bio-sourced and degradable. As with all polymers, the quality of the final plastic is dependent upon the catalyst used, with metal compounds such as zinc, aluminium, titanium and tin all emerging as possible catalysts. This work presents the synthesis and characterisation of several new β-diketonate and β-ketoiminate metal compounds as potential catalysts. The mechanism of activation for the ring opening metathesis polymerisation (ROMP) of lactide is still poorly understood, but the Lewis acidic catalysts are thought to bind to the carbonyl of the lactide. Our compounds have been designed with labile ancillary ligands which can easily be displaced, leaving a vacant 'active site' on the catalyst. In addition, this work also presents novel dimers and trimers, which are ideal for ROMP, as they can break apart into monomers yielding two metal centres each with a vacant binding site. The preliminary data for the ROMP of lactide via both dry melt and <i>in situ</i> reactions will also be discussed.

Aluminium and titanium metal complexes: Synthesis, characterisation and their application in ring opening metathesis polymerisation (ROMP)

256th National Meeting (2018)

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