Tannin-Based Copolymer Resins: Synthesis and Characterization by Solid State 13C NMR and FT-IR Spectroscopy.

Gianluca Tondi

doi:10.3390/polym9060223

Abstract

In recent years, the interest for bio-sources is rising exponentially and tannins extracts are one of the most interesting, easily-available, phenolic building blocks. The condensed tannins or proanthocyanidins are already known for their polymerization chemistry, which is the basis for several natural-based materials (e.g., adhesives, foams). In the present work we aim to observe the behavior of the extract of Acacia Mimosa (Acacia mearnsii) when reacted with several possible co-monomers at different relative amount, pH and temperature conditions. The more insoluble copolymers obtained with formaldehyde, hexamine, glyoxal, maleic anhydride, furfural and furfuryl alcohol were analyzed through solid state 13C NMR (Nuclear magnetic resonance) and FT-IR (Fourier Transform-Infrared) spectroscopy. The 13C NMR afforded the opportunity to detect: (i) aromatic substitutions and consequent poly-condensations for the majority of the hardeners studied; (ii) acylation for the maleic anhydride and also some; (iii) Diels–Alder arrangements for the furanic co-monomers; the FT-IR spectroscopy suggested that the formaldehyde and hexamine copolymers present a higher cross-linking degree.

Highlights

IntroductionThat is principally because is not easy to find natural alternative resources that can guarantee the same performance as synthetic polymers
Plastic is a common name for many different materials and the great majority of them are synthetic.That is principally because is not easy to find natural alternative resources that can guarantee the same performance as synthetic polymers
Mimosa (Acacia Mearnsii) tannin extract was provided by the company Silva team tannin extract was provided by theglyoxal company

Summary

Introduction

That is principally because is not easy to find natural alternative resources that can guarantee the same performance as synthetic polymers. Wool is mainly natural proteins synthesized directly by sheep, and cotton is a polymer of cellulose produced by a plant [1,2]. In both cases we are just the final users of these materials, applying physical treatment to obtain the requested properties. We modify the natural polymers chemically to have the opportunity to reuse them in different formations, such as in the case of viscose [3]. It is much more complicated to produce polymers from bio-resources which originally have a lower molecular mass

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Methods

Conclusion