Effectiveness of Esterification Catalysts in the Synthesis of Poly(Ethylene Vanillate)

Eleftheria Xanthopoulou,George Z Papageorgiou,Alexandra Zamboulis,Dimitrios N Bikiaris,Zoi Terzopoulou,Margaritis Kostoglou

doi:10.3390/catal11070822

Abstract

Over the last few decades, bio-based polymers have attracted considerable attention from both academic and industrial fields regarding the minimization of the environmental impact arising from the excessive use of petrochemically-based polymeric materials. In this context, poly(ethylene vanillate) (PEV), an alipharomatic polyester prepared from 4-(2-hydroxyethoxy)-3-methoxybenzoic acid, a monomer originating from lignin-derived vanillic acid, has shown promising thermal and mechanical properties. Herein, the effects of three different catalysts, namely titanium butoxide (TBT), titanium isopropoxide (TIS), and antimony trioxide (Sb2O3), on the synthesis of PEV via a two-stage melt polycondensation method are investigated. The progress of the reaction is assessed using various complementary techniques, such as intrinsic viscosity measurement (IV), end group analysis (AV), nuclear magnetic resonance spectroscopy (NMR), Fourier-transformed infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The thermal stability of the produced polyesters is studied by evolved gas analysis mass spectrometry (EGA-MS). Moreover, as the discoloration in polymers affects their applications, color measurement is performed here. Finally, theoretical kinetic studies are carried out to rationalize the experimental observations.

Highlights

Contemporary industrial polymerization technologies make the production of versatile polymeric materials with highly tunable properties possible and subsequently a plethora of applications in areas including the packaging, automotive, and engineering sectors
Owing to its structural similarity with terephthalic acid (TPA), vanillic acid (VA)-based materials are expected to demonstrate comparable thermal and mechanical properties to poly(alkylene terephthalates), which are a series of high performance petrochemically-based thermoplastic polyesters
As shown,ranged the calculated conversion resulted in a. These results indicate that resulted in a. These results indicate that demonstrate of -COOH groups titanium-based catalysts ranged from 80% to 85%, while the use 2 using greater catalytic activity during the esterification stage of poly(ethylene vanillate) (PEV), in accordance its greater catalytic activity during the esterification of PEV, in accordance withwith its terof Sb2O3 resulted in a 73%

Summary

Introduction

Contemporary industrial polymerization technologies make the production of versatile polymeric materials with highly tunable properties possible and subsequently a plethora of applications in areas including the packaging, automotive, and engineering sectors. The conversion of biomass to bio-based monomers, and subsequently polymers by means of biochemical and/or chemical transformations, constitutes the most important route toward the preparation of bio-based plastics like poly(lactic acid) (which, at the moment, is the most important bio-based polymer with many applications [7]) and other polymers, owing to the abundance and relatively low cost [8] Through this path, bio-based forms of conventional plastics such as bio-poly(ethylene terephthalate) and bio-poly(ethylene) [9] may be produced, as well as novel building blocks based on new aromatic precursors, reinforcing the transition from a linear to a circular economy [10]. The continuous progress concerning lignin depolymerization and purification [13,14,15], combined with the biotechnological production of vanillin [16,17,18,19], is defining more sustainable routes towards the preparation of vanillin, promoting vanillic acid as an excellent building block for the preparation of fully bio-based polymers

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Results

Conclusion