In the pursuit of environmentally friendly building blocks in polymer chemistry the utilization of bio-based monomers is highly desired. Fatty acids as bio-based monomers are considered as interesting due to their abundance, low cost and versatility. In recent studies we have shown that biomass such as birch bark and vegetable oils are excellent examples as source for retrieving bio-based monomers. In a first study it was shown that it was possible to extract pure cis-9,10-epoxy-18-hydroxyoctadecanoic acid (EFA) from birch bark by alkaline hydrolysis. EFA was used in order to investigate thermal or UV induced curing for thermosetting applications. During the thermally initiated process pure EFA was self-catalyzed without any addition of a catalyst. NMR and in situ real-time FTIR revealed competing reactions occuring and their relative reactivies. Moreover, in a “one-pot” approach it was possible to add other functiolities to EFA such as thiols without harming the epoxide group. A thiol-epoxy dual-functional polyester resin was synthesized by enzyme catalysis. The synthesized resin provided means for surface-modification possibilities by either reacting only the thiols or the epoxide selectively. The selectivity was chosen by UV induced cationic or chain/step wise polymerization. In addition, the uncreacted functionality was accessible and was reacted with desired molecule to change the surface properties. Epoxidized fatty acid derivatives from vegetable oils was also studied. During this study 3 different epoxidized fatty methyl esters were transesterified from vegetable oil and pured by coloumn chromatography. Usually, such fatty acid derivatives cure into soft network. In order to tune the mechanical properties of the final thermoset we were interested in extending 2,5-furandicarboxylic acid (FDCA) into epoxy thermosets. FDCA was first di-allylated followed by epoxidation of the allyls to form diglycidyl furan-2,5-dicarboxylate (DGFDC). By varying the degree of stoichiometry of both DGFDC and the respective epoxidized fatty acid methyl ester it was possible to tune the thermal and mechanical properties which resulted in thermosets with Tg in range of -23 oC – 105 oC. The cross-linking reaction was followed by both reactive DSC and in situ FTIR either by thermal or UV-induced cationic polymerization. For comparitive purposes diglycidyl Bisphenol-A (DGEBA) was also cross-linked with respective epoxidized fatty acid methyl ester.

Bio-based epoxy thermosets from fatty acid derivatives

2019 Spring National Meeting

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