Clicking renewable resources: Fatty acid derived monomers and related polymers via thiol-ene additions

Being aware of global warming, one result of using fossil resources as raw materials for fuel and industrial applications, environmental considerations become more important and inevitable. Using plant oils as raw materials for the synthesis of polymers is more sustainable, environmentally-friendly, and can also provide economic solutions to the above mentioned problems.[1,2] Especially castor oil is an example of a renewable raw material showing a great number of possibilities to be used as a renewable feedstock for the chemical industry.[3]
Additionally, thiol-ene addition reactions, which are considered to qualify as click chemistry, for monomer synthesis as well as polymerization seem to be an efficient tool for the production of materials offering manifold possibilities to complete our goal.[4,5] Up to now, this efficient reaction was only marginally und unsystematically studied with plant oils.[6,7] Herein, we report the application of thiol-ene coupling reactions as a facile synthetic route to modify 10-undecenoic acid, a castor oil derived platform chemical,[3] in order to synthesize
various monomers. A variety of functional groups, including e.g. –hydroxy and –methyl estergroups, were thus introduced under solvent- and initiator-free conditions in high yields. The prepared monomers were subsequently polymerized yielding hyperbranched as well as linear polyesters in high yields. All materials were fully characterized by GPC, 1H-NMR and DSC analysis, the results of which will be presented within this contribution.

References:
[1] C. H. Christensen, ChemSusChem, 2008, 1, 283-289.
[2] M. A. R. Meier, J. O. Metzger, U. S. Schubert, Chem. Soc. Rev. 2007, 36, 1788.
[3] H. Mutlu, M. A. R. Meier, Eur. J. Lipid Sci. Technol. 2010, accepted.
[4] C. E. Hoyle, T. Y. Lee, T. Roper, J. Polym. Sci., Part B: Polym. Phys. 2004, 42,5301.
[5] K. L. Killops, L. M. Campos, C. J. Hawker, J. Am. Chem. Soc. 2008, 130, 5062.
[6] G. B. Bantchev, J. A. Kenar, G. Biresaw, M. G. Han, J. Agric. Food Chem. 2009, 57, 1282.
[7] M. Black, J. W. Rawlins, Eur. Polym. J. 2009, 45, 1433.