Ring Metathesis

Ring Metathesis-87
The use of olefin cross metathesis in preparing functional polymers, through either pre-functionalisation of monomers or post-polymerisation functionalisation is growing in both scope and breadth.The broad functional group tolerance of olefin metathesis offers a wealth of opportunities for introducing a broad range of functional groups into the polymer backbone, tuning polymer properties and expanding potential applications.

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A less explored strategy is chemical functionalisation.

Due to the size of individual macromolecules, and entanglement of polymer chains, direct chemical modification is sometimes difficult but has received renewed attention in recent years with the growth of efficient methodologies to incorporate the desired functionality.

Similarly, ring-closing metathesis offers the ability to tune the polymer macrostructure and microstructure to similar effect.

In this review, we explore the importance of understanding selectivity in olefin cross metathesis in designing functional polymers, the manipulation of this reactivity to prepare (multi)functional polymers, and show how polymer systems can be constructed to favour ring closing and change backbone structure and properties.

ROM, as the name implies, opens rings to afford new, derivatised small molecules featuring two olefin fragments.

When no cross-partner is present, homopolymerisation is favoured, as in ROMP (from the ring form) or ADMET (from a diolefin monomer); these fields have been extensively reviewed much less work has been reported in the application of these reactions to polymer chemistry.Polymers are essential to our lives, providing the structure and function that underpins advances in materials science, medicine, energy and more.Polymeric materials have expanded well beyond commodity plastics to access specialty applications enabled by precise control of their architectures, molecular weights and dispersity, including methodologies to control polymer microstructure, macrostructure and co-monomer composition.Olefin metathesis catalysts; 1 Grubbs first generation catalyst, 2 Grubbs second generation catalyst, 3 Hoveyda–Grubbs second generation catalyst, 4 a derivative of Hoveyda–Grubbs catalyst (Zhan-1B) and 5 Schrock's catalyst.Particularly in CM, where the metathesis reaction is between two chemically distinct alkenes, selectivity can be a challenge.Fern was awarded a first class Master of Chemistry from the University of Edinburgh in 2013, including one year industrial experience working with Cytec Industries, USA.Her research is focussed on using olefin cross metathesis for the modification of biodegradable polymers through both novel monomer synthesis and copolymerisation techniques.Her research interests include synthetic organic methodologies, and the use of metathesis reactions for the synthesis of bioactive natural products and more recently post-polymerisation functionalisation.After undergraduate education at Mount Allison University and a Ph D at the University of British Columbia, he was awarded an NSERC Post-doctoral Fellowship to study at Imperial College London.To help overcome this problem, Grubbs devised an empirical model to aid in the design of selective CM reactions.This model, alongside the aforementioned development of more active metathesis catalysts, now permits the application of CM reactions to more complex systems, including polymers.


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