Synthesis of Biobased Soft-Packaging Polyesters from 2,5 Thiophenedicarboxylic Acid

Demand for light-packaging materials for food and beverages is on the rise globally, especially in developing countries where several depend on packaged food. Furthermore, poly(ethylene terephthalate) (PET) a semi-crystalline thermally stable polyester, is widely used for carbonated soft drink, water and juice bottles, but shows a poor degradability properties after their lifespan. In this investigation, a series of novel random partially degradable poly(carbonate- co -esters) (PTB/PTBC n ) containing 2,5-thiophenedicarboxylic acid (TDCA), and different amounts of bis(2-hydroxyethoxy)benzene (BHEB) and 1,4-cyclohexanedimethanol (CHDM) sub-units were successfully synthesized via a two-step melt polymerization as a facile and green semi-continuous process. The copolymers were thermally stable with tunable T g values ranging from 47 to 71 °C, while their 5% decomposition temperature (T d, 5% ) under N 2 varied from 463 to 432 °C. Herein, focus was made on the synthesis of eco-friendly polyesters with satisfactory O 2 -gas barrier properties (5.5 cm 3  mm/m 2  × day × atm) at 25 °C suitable for most packaging applications. The mechanical and thermal analysis of PTB and PTBC n polyesters revealed excellent properties comparable to commonly used packaging materials such as poly(vinyl chloride), poly(lactic acid) and PET, whereby the incorporation of cyclohexane (CHDM) and phenyl (BHEB) rings units greatly enhanced the thermal and mechanical properties, transparency, oxygen permeability, and biodegradability of these polyesters. Graphical Abstract