(8f) Renewable and Recyclable Bioplastics from Bio-Derived Monomer

New eco-friendly materials and technologies are urgently needed to prepare and recycle/upcycle the plastics through the value chain enabling a circular and sustainable economy. This research emphasis sustainable ways to turn non-food biomass into recyclable polymer. 4,4’-biphenyldicarboxylic acid (BPDA/diacid) has been known as either a polyethylene terephthalate (PET) additive to produce copolymers or a feedstock to produce polyesters with improved properties. To make the process renewable BPDA was produced by the oxidation of 4,4’-dimethylbiphenyl (DMBP) which has been successfully synthesized from C5 sugar-derived 2-methyl furan. An esterification process was used to obtain polymer grade 4,4'-biphenyl dicarboxylate (BPDC/diester) from BPDA. Further, the diester was blended with dimethyl terephthalate (DMT), to produce copolymers with either similar or superior properties to commercial PET resins. Palladium acetate was used as catalyst in the oxidative coupling of 2-methylfuran with oxygen, and La-triflates were employed to catalyze the tandem Diels-Alder-Dehydration of 5,5’-dimethylbifuran and ethylene to form DMBP (83% DMBP yield in 18 h). The extension of the Mid-Century (MC) process (used to produce terephthalic acid monomer from p-xylene) to selectively oxidize DMBP to the BPDA monomer is non-trivial as DMBP is a solid at room temperature. Hence, melt DMBP continuously fed into the reactor containing Co/Mn/Br salts dissolved in acetic acid at MC conditions (~20 bar, 195 °C). A solid obtained with 98.7% BPDA purity and 91.2% yield with complete DMBP conversion and ~92% carbon balance. Our results suggest that BPDA can also be produced industrially via the MC process. The BPDA was esterified and obtained ~90% BPDC yield with 97% purity in the solid. Subsequently, polymerization was performed using 20-30% BPDC as a co-monomer with dimethyl terephthalate (DMT) in ethylene glycol with Ti(OBu)₄ catalyst to partially replace petro-based terephthalic acid. The properties of the blend will be discussed for engineering applications like films and fibers.