Direct transformation of fatty acid-derived monomers from dimer acid manufacturing into valuable bio-plasticizers with high plasticization and compatibilization

Direct transformation of monomer fatty acids derived from the dimer acid manufacturing into high value-added green plasticizers represents a sustainable approach for reutilizing industrial wastes. However, this process is challenging due to the few double bonds and long-chain alkyl in monomer fatty acid-based derivatives, resulting in poor compatibility with polymer matrix and inferior plasticization. Herein, we develop a sustainable and low-cost strategy via direct esterification between monomer fatty acids and polyethylene glycol methyl ether to produce plasticizers featured by high plasticization and compatibilization. The performances of monomer acid-based ethoxylated esters as resulting plasticizers for nitrile butadiene rubber were highly structure-dependent. Extensive experiments demonstrated that oxethyl unit played critical roles in both improving the compatibility between monomer acid-based ethoxylated esters and nitrile butadiene rubber and in promoting the dispersion of carbon black in nitrile butadiene rubber matrix. Specially, the processing, freezing resistance, oil resistance, thermal and mechanical stabilities of nitrile butadiene rubber plasticized by monomer acid-based ethoxylated esters with three or four oxethyl units were comparable or better than those of nitrile butadiene rubber blended with dioctyl phthalate. This study opens a simple, general and industrialized strategy to produce valuable and sustainable plasticizers as alternatives of toxic dioctyl phthalate.