Poly(hexylene vanillate): Synthetic Pathway and Remarkable Properties of a Novel Alipharomatic Lignin-Based Polyester
Eleftheria Xanthopoulou, Zoi Terzopoulou, Alexandra Zamboulis, Savvas Koltsakidis, Dimitrios Tzetzis, Katerina Peponaki, Dimitris Vlassopoulos, Nathanaël Guigo, Dimitrios Ν. Bikiaris, George Z. Papageorgiou
Abstract
The negative environmental effects of conventional polymeric materials have intensified the research toward the production of biobased counterparts. Vanillic acid (VA), a vanillin oxidation product, is a relatively new and most promising aromatic monomer for the synthesis of biobased polyesters. In this work, the synthesis of a new, high molecular weight alipharomatic polyester, poly(hexylene vanillate) (PHV), using 4-(6-hydroxyethoxy)-3-methoxybenzoic acid via a two-stage melt polycondensation method is reported. The success of the polymerization was confirmed using nuclear magnetic resonance spectroscopy (NMR) and Fourier-transformed infrared spectroscopy (FTIR), while the number-average molecular weight (Mn) was estimated by size-exclusion chromatography (SEC). Moreover, the thermal behavior of PHV was determined with differential scanning calorimetry (DSC), and insights on the thermal stability and degradation mechanism of PHV were given. The mechanical and thermomechanical properties of the synthesized material were investigated, revealing a thermoplastic elastomer behavior, with elastic recovery at room temperature, associated with the formation of a mesophase status. Finally, rheological tests were applied, indicating that PHV is easily processable and fully recoverable upon yielding and flow cessation.