Fully biobased epoxy resins from ring opening polymerization of epoxidized vegetable oils with renewable polyacids

Authors: Moser, Bryan

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/13/2023
Publication Date: 3/17/2024
Citation: Moser, B.R. 2024. Fully biobased epoxy resins from ring opening polymerization of epoxidized vegetable oils with renewable polyacids. American Chemical Society Spring Meeting - Many Flavors of Chemistry. Paper No. 4001531.

Interpretive Summary:

Technical Abstract: The most widely used epoxy resins are based on DGEBA, which is derived from BPA and epichlorohydrin. The outstanding performance characteristics of the resins are conveyed by the BPA moiety (toughness, rigidity, and thermal stability), the ether linkages (chemical resistance), and the hydroxyl and epoxy groups (adhesiveness). DGEBA and its analogues are typically cured with anhydrides, aliphatic amines, or polyamides, depending on the desired end properties. However, these materials are petroleum-derived and thus not renewable, the resins lack biodegradability, and BPA is a known endocrine disruptor. Therefore, renewable and sustainable alternatives with similar or superior performance are needed. In this study, epoxidized vegetable oils cured with renewable polyacids were investigated as alternatives to commercial epoxy resins. Fully biobased resins were efficiently synthesized from non-edible field pennycress (Thlaspi arvense L.) oil following a two-step sequence in which the oil was epoxidized by in situ-generated performic acid and then cured with citric and itaconic acids. Ring opening polymerization reactions were self-catalyzed, solvent-free, and conducted at 120 °C for 5 – 25 h. Analogous polymers were prepared from epoxidized soybean oil to serve as reference comparisons. The influence of comonomer combination and curing time on properties of the resulting thermosetting resins is reported. Crosslink density, storage modulus, tensile strength, and gel content increased with cure time. Citrate-based polymers had higher crosslink densities than itaconate-based polymers due to the greater functionality of citric acid versus itaconic acid, which resulted in higher glass transitions, tensile strengths, and storage moduli. Finally, the lower oxirane content of epoxidized pennycress oil versus epoxidized soybean oil resulted in lower crosslink density, storage modulus, tensile strength, and elongation at break. Overall, the epoxy networks had promising properties that were tunable by selection of appropriate comonomer combinations and curing times.