ADMET under vacuum

The equilibrium of the ADMET polymerization is forced towards high polymer by running bulk polymerizations under vacuum to remove ethylene. Working under bulk conditions or in solution, ADMET polymer products have been isolated up to 80 kg mol using [Mo] on hydrocarbon monomers and up to 70 kg mol" using [Ru]" on peptide functionalized monomers [39,40]. 

Most often, ADMET reactions are conducted in the bulk state (where the catalyst is dissolved in neat monomer) and under reduced pressure (high vacuum) to drive the equilibrium toward polymer formation by maximizing the monomer concentration and removing the ethene by-product. 

Liquid ADMET monomers often become so viscous that magnetic stirring is impossible. There are several solutions to this. One is to attach a strong horseshoe or other magnet to a mechanical stirrer and rotate it very slowly under the vessel and temperature bath to slowly agitate the polymer melt. Another solution is to use a high viscosity mechanical stirrer if the polymer is a viscous melt Vacuum adapters for the stirring shaft are available, so that the vacuum method may be used with mechanical stirrers. 

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