Preparation and Characterization of Bio-Based Polyesters Derived from Xylochemicals

The utilization of bio-based building blocks to replace fossil-based precursors is an attractive area of research in modern polymer science and engineering. Bio-based building blocks enable the utilization of largely untapped resources and increase the base of chemicals that scientists and engineers can draw upon to obtain desired polymer properties. The preparation and characterization of novel, aromatic polyesters derived from xylochemicals (bio-based building blocks) is presented. Bisguiacol (BG), a bisphenolic monomer was synthesized via an electrophilic aromatic condensation of two lignin-based molecules. BG was polymerized with three aliphatic, linear diacid chlorides (DACs) of varying carbon chain length: succinyl chloride (4C), glutaryl chloride (5C) and, adipoyl chloride (6C). BG was also polymerized with terephthaloyl chloride; an aromatic DAC. These DACs were chosen in order to observe the effects of DAC chain length and structure on the polyesterification kinetics and thermomechanical properties of the polymers. Furthermore, analogous fossil-based polyesters were synthesized for each bio-based polyester by polymerizing bisphenol A (BPA) with each DAC. The bio-based polyesters were characterized to determine the structure-property relationships and compared with their fossil-based analogues to assess their validity as alternatives to current industry standards. The polymers were characterized via ¹H NMR, DSC, and GPC techniques. It was observed that as the carbon chain length of the aliphatic DACs decreased, the glass transition temperature (T_g) increased from 18.2°C for poly(BG-adipate) to 36.5°C for poly(BG-succinate). Poly(BG terephthalate) displayed a T_g of 132.5°C. We will present the results of this study illustrating that these new polymers are viable alternatives to fossil-based materials currently employed in the plastics industry.