Renewably sourced polytrimethylene ether glycol by superacid catalyzed condensation of 1,3-propanediol

Abstract

In this paper we describe the synthesis of a new 100% renewably sourced polymer, polytrimethylene ether glycol (polyol). This is an alternative to petroleum-sourced polytetramethylene ether glycol (PTMEG) and polypropylene glycol (PPG) and adds to the slowly expanding list of polymers from renewables, such as polylactic acid. The polymer is based upon a renewably sourced monomer, 1,3-propanediol (PDO), which itself has a lower environmental footprint compared to the chemically derived monomer, with both lower amount of green house gas emissions and energy use, during formation. Herein we discuss the development of polymerization conditions to provide polytrimethylene ether glycol with low color and low unsaturated end groups using the superacid tetrafluoroethane sulfonic acid (TFESA, b.p. 212 °C). The initial high color (brown) and high unsaturated impurities of the polymer, has been overcome by careful control of the processing conditions, leading to a new class of 100% renewably-sourced polymers. Preliminary kinetic analyses are also reported.