Environmentally Friendly Synthesis of Cardanol-Based Polyesters and Their Application as Poly(lactic acid) Additives

Abstract

Byproducts derived from the food industry are an interesting biomass to valorize as they are cheap to source, their generation does not compete with food and feed production, and their utilization solves the waste disposal issue. In this work, we focused on the production of a series of polyesters using a cardanol-derived diol produced from the inedible shell of cashew nuts. The synthesized polymers are 100% biobased since the diacid components of the structure (adipic acid and succinic acid) can also be bio-derived monomers. Moreover, the overall process is a paradigm for a green circular economy as the synthesis was conducted via mild enzymatic catalysis (T < 90 °C) in a solventless system. The final workup procedure to recover the materials was conducted using the biomass-derived solvent methyl-tetrahydrofuran, therefore presenting a methodology that does not include any petroleum-based component. This work led to the biocatalyzed synthesis of linear cardanol-based polyesters having mean average molecular weights between 1800 and 4100 g mol–1 and low dispersity values (2 < D̵), which were used to plasticize poly­(lactic acid), leading to an increase in the elongation at break of the resulting blends.

Amino acids as bio-organocatalysts in ring-opening copolymerization for eco-friendly synthesis of biobased oligomers from vegetable oils

“…It is important to mention that synthetic bio-polyesters could be used as plasticizers to design novel polymeric materials including coating precursors due to their low molecular weight. 48–50…”

“…It is important to mention that synthetic bio-polyesters could be used as plasticizers to design novel polymeric materials including coating precursors due to their low molecular weight. [48][49][50] The thermal properties of the prepared bio-oligomers poly (EOO-co-PA), poly(EOO-co-MA), poly(EOO-co-SA), and poly (EOO-co-GA) were investigated using thermogravimetric analysis (TGA) (Table 3). The thermal decomposition temperature at 5% mass loss (T d 5%) showed a value of around 100 °C for poly(EOO-co-PA), indicating the presence of occluded organic solvents or water in this oligomer, while poly(EOO-co-MA), poly(EOO-co-SA), and poly(EOO-co-GA) exhibited higher T d 5% values between 208 to 235 °C (see ESI †).…”

Isolation of Cardanol Fractions from Cashew Nutshell Liquid (CNSL): A Sustainable Approach

“…Thus, plant phenolics represent important and time-honored raw materials for innumerable industrial products, including thermoset [12] and thermoplastic [13] polymers [14,15]. Furthermore, the inherent presence of various functionalities is one of the vivid features as it enables various structural modifications to design and stimulate diversity in bio-based precursors for polymers [16][17][18] and nanoparticles/nanofibers [19,20]. The simplest method of extracting these phenolics is via a direct isolation route, either from natural sources or by transforming waste from agro-based industries [21].…”