Novel thermoset formulations from cannabidiol (CBD) oil
Cannabidiol (CBD) is a structurally versatile aromatic terpene containing a resorcinol unit with a C-5 alkyd chain meta to the phenolic hydroxyls and a terpenoid moiety (R and S limonene) para to the C-5 alkyd chain, making this material highly reactive towards various means of functionalization for...
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| Published in: | Next materials Vol. 6; p. 100261 |
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| Main Authors: | , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier Ltd
01-01-2025
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Cannabidiol (CBD) is a structurally versatile aromatic terpene containing a resorcinol unit with a C-5 alkyd chain meta to the phenolic hydroxyls and a terpenoid moiety (R and S limonene) para to the C-5 alkyd chain, making this material highly reactive towards various means of functionalization for thermoset resin synthesis. In this study, CBD was synthetically modified to obtain a di-methacrylate, a di-epoxy, and a tetra-epoxy resin via well-established conventional methods. The structural analyses of the various modified resins were performed via spectroscopic, chromatographic, and titration techniques demonstrated the full conversion of hydroxyls to methacrylate or epoxide units, while the terminal double bonds on the terpenoid unit were minimally epoxidized via hydrogen peroxide unlike internal double bonds. CBD dimethacrylate (CBDDMA) was thermally cured with bio-derived reactive diluents menthyl methacrylate (MM) and methacrylated fatty acid (MFA), and cardanyl methacrylate and with petro-based styrene (St), all at 35 wt% content. A Di-glycidyl ether version of CBD (CBDDGE) was also thermally cross-linked with petro-derived 4,4′-methylenebiscyclohexanamine (PACM), furan-derived 5,5′-methylenedifurfurylamine (DFDA), and a DFDA-cardanol-derived phenalkamine (PKA) at stoichiometric amounts. For comparison, CBD tetra-epoxy (CBDTE) was also cured with PACM at stoichiometry. The post-cured thermoset formulations were evaluated for their extent of cure via infrared spectroscopy (IR) showed high extent of cure for the vinyl ester systems and almost full conversion of di-epoxy amine systems while the tetra-epoxy version with secondary epoxies were minimally cross-linked due to their stearic limitations. All the post-cured CBD based thermoset systems were analyzed for their thermo-physical performance via Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA), and Differential Scanning Calorimeter (DSC). The glass transition temperatures (Tg’s) are found to range between − 4 and 110 °C for vinyl ester systems and between 51 and 110 °C for epoxy-amine systems as obtained via loss modulus and room temperature storage modulus 0.9–2.0 GPa and 1.9–2.2 GPa as obtained from storage modulus curves at 25 °C depending on the selection of reactive diluent and the curing agent. CBD-derived thermoset networks demonstrated adequate reactivity and thermal resistance similar to the thermosets derived from other bio-originated oils, yet lower than bisphenol A (BPA) derived thermoset networks with the same diluents and amine cross-linkers due to the presence of bulky side chains and cycloaliphatic moieties. |
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| ISSN: | 2949-8228 2949-8228 |
| DOI: | 10.1016/j.nxmate.2024.100261 |