Thermal and mechanical properties of polymer networks prepared by the thiol-ene reaction of a vanillin/acetone condensate and its related compounds

Abstract

• Vanillin and benzaldehyde condensates with acetone were cured with a tetrathiol, S4P. • A diallylated vanillin/acetone condensate (DADVAT) was cured with S4P. • Radical-initiated photo/thermal cure and thermal cure using Et 3 N were investigated. • Photo/thermal dual cured DADVAT/S4P 1/1 exhibited excellent physical properties. • The thiol-ene reaction of the enone/thiol groups was promoted by the basic catalyst. A new bio-based diallyl compound, DADVAT, was synthesized by the allylation of 2,5-bis(4-hydroxy-3-methoxybenzylidene)acetone (DVAT), which had been prepared by the cross-aldol condensation of vanillin and acetone. The radical-initiated photothermal thiol–ene reactions of DADVAT/pentaerythritol tetrakis(3-mercaptopropionate) (S4P) at feed molar ratios of 1/1 and 2/1, DVAT/S4P, and trans,trans -dibenzylidene acetone (DBAT)/S4P at a molar ratio of 2/1 produced bio-based polymer networks (ptDADVAT-S4P-11, ptDADVAT-S4P-21, ptDVAT-S4P-21, and ptDBAT-S4P-21). The thermal and mechanical properties of the dual cured polymer networks were compared with those of thermally cured products (tbDADVAT-S4P-21 and tbDBAT-S4P-21) at a molar ratio of 2/1 using triethylamine as a basic catalyst for the nucleophilic thiol–ene reaction. ptDADVAT-S4P-11 displayed excellent thermal and mechanical properties compared to the other cured products. tbDADVAT-S4P-21 and tbDBAT-S4P-21 exhibited better thermal and mechanical properties than ptDADVAT-S4P-21 and ptDBAT-S4P-21, respectively, because the thiol–ene reaction of the enone and thiol groups is promoted by the basic catalyst rather than the radical initiators.