Toward low-misting leathers from environmentally friendly ricinoleic acid-based fatliquoring agents

In this work, an amidated hydroxylated ricinoleic acid (MRH) was developed from natural ricinoleic acid and commercially available thioglycerol and monoethanolamine by simple and efficient thiol-ene click and amidation reactions. The resulting MRH was subsequently used as an environmentally friendly, low-misting fatliquor for premium automotive interior leathers. In addition, theoretical speculations using molecular dynamics simulations and routine experimental methods for determining the misting resistance and the percentage of free oil in the MRH-treated leather were systematically investigated. The hydroxyl groups and the amide group within MRH are able to form firm chemical bonds with collagen fibers of the leather, as evidenced by higher E_binding (122.84 kcal/mol) and lower diffusion coefficient (0.000095 Ų/ps) obtained from molecular dynamics simulations, the lower free oil content (11.42%), and the lower misting value (4.82 mg) of MRH-treated leather. Therefore, the MRH fatliquoring agent did not migrate out of the collagen fibers. Overall, bio-derived ricinoleic acid can be modified to enable the design of sustainable fatliquors for low-misting-value automotive upholstery leather. Furthermore, the fatliquoring effluent was also biodegradable, all of which contributed to a cleaner production of leather fatliquor.