Aromatic thermotropic polyesters based on 2,5-furandicarboxylic acid and vanillic acid

This paper addresses a route to synthesize bio-based polymers with an aromatic backbone having a liquid crystalline (LC) phase in the molten state. The LC phase is employed to achieve uniaxial orientation during processing required in e.g. fiber spinning. For this purpose 2,5-furandicarboxylic acid (2,5-FDCA) and O-acetylvanillic acid (AVA), obtained from natural resources, are used as monomers. Similar to the 2,6-hydroxynapthoic acid used to perturb the crystalline packing of poly(oxybenzoate) in the Vectran® series, these bio-based monomers are used to lower the crystal to liquid crystal transition temperature. Considering that the poly(oxybenzoate) can also be obtained from natural resources, the adopted route provides the unique possibility to synthesize bio-based polymers that can be used for high performance applications. To obtain the desired polymers, a synthetic route is developed to overcome the thermal instability of the 2,5-FDCA monomer. Experimental techniques, such as optical microscopy, FTIR spectroscopy, DSC, and TGA are employed to follow the polymerization, phase transitions and evaluate thermal stability of the synthesized polymers.