Further Step in the Transition from Conventional Plasticizers to Versatile Bioplasticizers Obtained by the Valorization of Levulinic Acid and Glycerol

Valorization of glycerol and levulinicacid by a solvent-freeand mild-condition reaction to obtain a high-efficiency bioplasticizersuitable for different polymers.In the last two decades,the use of phthalates has beenrestrictedworldwide due to their well-known toxicity. Nonetheless, phthalatesare still widely used for their versatility, high plasticization effect,low cost, and lack of valuable alternatives. This study presents thefully bio-based and versatile glycerol trilevulinate plasticizer (GT)that was obtained by the valorization of glycerol and levulinic acid.The mild-conditions and solvent-free esterification used to synthesizeGT was optimized by investigating the product by Fourier transforminfrared and NMR spectroscopy. An increasing content of GT, from 10to 40 parts by weight per hundred parts of resin (phr), was testedwith poly(vinyl chloride), poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(lactic acid), and poly(caprolactone),which typically present complicatedprocessability and/or mechanical properties. GT produced a significantplasticization effect on both amorphous and semicrystalline polymers,reducing their glass-transition temperature and stiffness, as observedby differential scanning calorimetry measurements and tensile tests.Remarkably, GT also decreased both the melting temperature and crystallinitydegree of semicrystalline polymers. Furthermore, GT underwent enzyme-mediatedhydrolysis to its initial constituents, envisioning a promising prospectivefor environmental safety and upcycling. Furthermore, 50% inhibitoryconcentration (IC50) tests, using mouse embryo fibroblasts,proved that GT is an unharmful alternative plasticizer, which makesit potentially applicable in the biomedical field.