Renewable poly(thioether-ester)s from fatty acid derivatives via thiol-ene photopolymerization

Authors: Moser, Bryan; Doll, Kenneth - Ken; Peterson, Steven - Steve

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2019
Publication Date: 6/11/2019
Citation: Moser, B.R., Doll, K.M., Peterson, S.C. 2019. Renewable poly(thioether-ester)s from fatty acid derivatives via thiol-ene photopolymerization. Journal of the American Oil Chemists' Society. 96(7):825-837. https://doi.org/10.1002/aocs.12244.
DOI: https://doi.org/10.1002/aocs.12244

Interpretive Summary: This research describes a sustainable route to a new set of renewable polymers from vegetable oils. Renewable polymers are important because they represent bio-based alternatives to existing petrochemically-based materials, which often cause water and soil pollution in addition to negative health effects. This research discovered that fatty acids derived from vegetable oils can be readily converted into thermoplastic polymers using a simple, rapid and mild photochemical technique in high yield. These polymers have potential applications as coatings, thickening agents or organogels. This research may ultimately expand markets for bio-based polymers, thus reducing the environmental impact of and demand for petroleum-derived products while simultaneously enhancing rural economies by increasing the use of agricultural materials.

Technical Abstract: Partially bio-based poly(thioether-ester)s were obtained in high conversion from thiol-ene photopolymerization of fatty dienes with dithiols utilizing mild, solventless reaction conditions. Fatty dienes were synthesized by esterification of 9-decenoic acid, a terminally unsaturated medium-chain fatty acid that can be obtained from ethenolysis of oleic acid, with ethylene glycol and 9-decen-1-ol to yield bio-based dienoic monomers amenable to subsequent thiol-ene polymerization. Polycondensation with 1,2-ethanedithiol (EDT) and 1,3-propanedithiol (PDT) gave a series of semi-crystalline poly(thioether-ester)s with degrees of polymerization that ranged from 29 to 85, polydispersity indices between 2.81 and 4.38, and glass transitions from -36.8 to -25.7 deg C. The polymers were elastic at room temperature, with EDT-linked materials exhibiting greater elasticity than the corresponding PTD-linked polymers. All polymers were thermally stable below 320 deg C, with 10% mass loss (T10) occurring above 338 deg C. Enthalpies of fusion increased with higher relative crystallinity and were greater than the corresponding enthalpies of crystallization. The polymers were soluble in nonpolar solvents such as chloroform and THF but resisted dissolution in more polar solvents such as chloroform and THF but resisted dissolution in more polar solvents with dielectric constants above 10. Furthermore, the polymers were susceptible to acidic hydrolysis but resisted basic hydrolysis at room temperature.