Biobased Polyurethane Coatings with High Biomass Content: Tailored Properties by Lignin Selection

• Published in: ACS sustainable chemistry & engineering Vol. 7; no. 13; pp. 11700 - 11711
• Main Authors: de Haro, Juan Carlos, Allegretti, Chiara, Smit, Arjan T, Turri, Stefano, D’Arrigo, Paola, Griffini, Gianmarco
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01.07.2019
• Subjects: Lignin; Vanillic acid; Biobased; Biomass; Coating; Polyurethane
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.9b01873

New biobased polyurethane (PU) coatings with high lignin content were developed and characterized in this work. These materials were based on a α,ω-diisocyanate monomer (1,4-bis­(4-isocyanato-2-methoxyphenoxy)­butane, VA-NCO) obtained from lignin-derived vanillic acid and its further cross-linking reaction with three different nonchemically modified technical lignins obtained from different pulping processes, namely, mild acetone organosolv, kraft, and soda. After determining the optimal VA-NCO/lignin mass ratio for each type of lignin, an in-depth characterization of the obtained PU coatings highlighted their high biomass content, effective cross-linking, improved thermal stability, hydrophobic character, good adhesion performance on different types of substrates, and tunable mechanical response. These properties were found to be well-correlated to the chemical–physical features of the parent lignins used (namely, molecular weight, glass transition temperature, distribution of phenylpropane subunits, and −OH content), thereby suggesting the possibility to predictively tailor the characteristics of such biobased PU coatings by lignin selection. The results of this study demonstrate that the reaction of a lignin-derived biobased diisocyanate with different chemically unmodified technical lignins represents an interesting pathway for the production of thermosetting PU coatings with a high biomass content that can find application as high-performance biobased materials alternative to traditional petroleum-based platforms.