Design, preparation and properties of novel renewable UV-curable copolymers based on cardanol and dimer fatty acids

• Novel vinyl ester resin (VER) monomer, cardanol methacrylate (CDMA) was prepared.
• The copolymers of CDMA and dimer fatty acids based VER monomer were also prepared.
• Cardanol (CD) and dimer fatty acids (DA) are both eco-friendly renewable chemical feedstocks.
• The prepared copolymer is a perfect combination of rigid and flexible molecular structure.
• To our knowledge, this is the only report to prepare fully bio-based VER copolymers.

A cardanol-based UV-curable vinyl ester (VE) monomer was prepared via simple esterification, and its successful synthesis was demonstrated by FTIR and 1H-NMR. In order to improve its rigidity, it was mixed with certain proportions of another reactive bio-based VE monomer, maleic anhydride modified dimer fatty acids polymerized glycidyl methacrylate (MA-m-DA-p-GMA) which had rigid and strong polar groups, and then a series of UV-cured copolymers were prepared from the two VE monomers. The UV curing process was monitored by FTIR analysis. The tensile and thermal properties of the cured copolymer films were also investigated. UV curing analysis demonstrated that the double bonds in the mixed VE could be converted to ultimate curing level within 40 s. Tensile tests showed the prepared copolymers had a tensile strength of 8.86 MPa. Dynamic mechanical analysis (DMA) revealed the copolymers had relatively high glass transition temperature (Tg) from 40 to 60 °C. Thermogravimetric analysis (TGA) showed the copolymers containing higher content of CDMA had higher thermal stability, and all copolymers’ main thermal initial decomposition temperatures were above 410 °C, indicating the copolymers had certain thermal stability. These copolymer films can be used as eco-friendly materials in coatings and other applications to replace the currently used petroleum-based polymers.

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