Enzymatic synthesis of kraft lignin-acrylate copolymers using an alkaline tolerant laccase

Journal Article · 22 April 2022 · Applied Microbiology and Biotechnology

DOI: https://doi.org/10.1007/s00253-022-11916-z · OSTI ID:1864375

Arefmanesh, Maryam; Vuong, Thu V.; Nikafshar, Saeid; Wallmo, Henrik; Nejad, Mojgan; Master, Emma R.

Abstract Softwood kraft lignin is a major bioresource relevant to the production of sustainable bio-based products. Continued challenges to lignin valorization, however, include poor solubility in organic solvents and in aqueous solutions at neutral pH. Herein, an alkaline tolerant laccase was used to graft acrylate functionalities onto softwood kraft lignin, which is expected to enhance the reactivity of lignin with isocyanate when producing bio-based polyurethanes. Proton nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and high-performance liquid chromatography were used to confirm successful grafting of the acrylate monomer onto lignin and verify the importance of including tert-butyl hydroperoxide as an initiator in the grafting reaction. Laccase-mediated grafting of softwood kraft lignin under alkaline conditions produced lignin products with approximately 30% higher hydroxyl value and higher reactivity toward isocyanate. The reported enzymatic and aqueous process presents an opportunity for the sustainable valorization of softwood kraft lignin. Key points • Softwood kraft lignin displayed high phenolic hydroxyl content, polydispersity index and average molecular weight • Grafting hydroxyethyl acrylate (HEA) monomer onto kraft lignin by laccase was successful at 60 °C and alkaline conditions • Lignin-HEA grafted copolymer showed an increase in total OH value and an increase in average molecular weight

• Research Organization: Michigan State Univ., East Lansing, MI (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: EE0008148
• OSTI ID: 1864375
• Journal Information: Applied Microbiology and Biotechnology, Journal Name: Applied Microbiology and Biotechnology Journal Issue: 8 Vol. 106; ISSN 0175-7598
• Publisher: Springer Science + Business MediaCopyright Statement
• Country of Publication: Germany
• Language: English