Acyclic Triene Metathesis ATMET

Another method to create new materials from polymerized plant oils is though acyclic triene metathesis (ATMET) polymerization. In this process, hyper-branched polymers are created beginning with a triglyceride that contains three alkene bonds. These hyperbranched polymers can display different physical attributes, such as lower viscosity and increased solubihty, when compared to their linear analogs. 

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Acyclic triene metathesis (ATMET) polymerisation is a particular ADMET application useful in vegetable oils. ADMET can also be used for the polymerisation of triglycerides, offering the possibility to obtain branched polymers directly from plant oils without prior chemical modification, thereby helping to further minimise the environmental impact of snch materials. This type of polymerisation was termed ATMET with reference to monomer functionality [51]. 

To obtain a branched polymer, acyclic triene metathesis (ATMET) can be used. As shown in Fig. 3.10, self-metathesis of a polyunsaturated TAG (the triene ie, triolein in the figure) would yield a hyperbranched polymer devoid of cross-links (Biermann et al., 2010). Of note, through employment of methyl acrylate as chain stopper, the resultant polymer will possess polymerizable carboxylic acid methyl ester end groups that can undergo further polymerization. 

FIGURE 3.10 Acyclic triene metathesis (ATMET) of triolein, using methyl acrylate as chain stopper. Adapted from Biermann, U., Metzger, J.O., Meier, M.A.R., 2010. Acyclic triene metathesis oligo- and polymerization of high oleic sunflower oil. Macromol. Chem. Phys. 211, 854-862. 

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