Terpenes as natural building blocks for the synthesis of hierarchically porous polymers: bio-based polyHIPEs with high surface areas

Abstract

PolyHIPEs are hierarchically porous polymers which are generally synthesised from synthetic constituents produced from fossil fuels. The need to produce sustainable materials makes terpenes great candidates for the preparation of polyHIPEs as they possess polymerisable functionalities, while being abundant in various plants and flowers. In this study limonene, carvone and myrcene are used to produce bio-based polyHIPEs by utilising multifunctional acrylates (trimethylol propane triacrylate (TMPTA) and pentaerythritol tetraacrylate (PETA)) as the comonomers in the polymerisation process. By using the two monomer units it was possible to synthesise poly(limonene-co-TMPTA), poly(limonene-co-PETA), poly(carvone-co-TMPTA), poly(carvone-co-PETA), poly(myrcene-co-TMPTA) and poly(myrcene-co-PETA) HIPEs. The terpene and acrylate ratios are varied to study the incorporation of the terpenes into the polyHIPE and the effects on the morphological properties. While the synthesis of terpene-based polyHIPEs was successful, the degree of limonene and carvone incorporation reduces when the content thereof in the HIPE mixture is increased. The synthesised polyHIPEs had a pore diameter ranging from 5.51 to 11.63 μm, while the specific surface area ranged from 2.7 m² g⁻¹ and up to approximately 300 m² g⁻¹. This study is the first study that demonstrates the possibility of preparing polyHIPEs from limonene and carvone. Additionally, it shows that it is possible to synthesise porous polymers from sustainable constituents.