Recombinatorial approach for the formation of surface-functionalised alkaline-stable lignin nanoparticles and adhesives. Issue 2 (21st December 2022)

• Record Type: Journal Article
• Authors: Ferruti, Federica; Pylypchuk, Ievgen; Zoia, Luca; Lange, Heiko; Orlandi, Marco; Moreno, Adrian; Sipponen, Mika H.
• Is Part Of: Green chemistry. Volume 25:Issue 2(2023)
• Page Start: 639
• Page End: 649
• Publication Date: 2022-12-21
• Subjects: Environmental chemistry -- Industrial applications -- Periodicals; Environmental management -- Periodicals; 660
• DOI: 10.1039/d2gc03406a
• Languages: English
• ISSNs: 1463-9262

Abstract

Abstract : Fractionate, selectively epoxidize, and recombine. Alkaline resistant lignin nanoparticles and competitive particle adhesives are achieved in a material-efficient manner, i.e., without significant waste generation from the lignin raw material. Abstract : Lignin nanoparticles (LNPs ) are considered as intriguing green, renewable alternatives to fossil-based nanomaterials. However, the predisposition of LNPs to dissolve under alkaline conditions makes covalent surface functionalisation in the dispersion state difficult and limits applications demanding morphological stability under challenging pH conditions. Mechanistic studies suggest that during the formation of LNPs by nanoprecipitation the higher molecular weight fractions of lignin likely start precipitating first, while the low molecular weight fractions tend to deposit later and thus locate on the outer shell. Capitalising this aggregation pattern, the present work presents a strategy to prepare surface-functionalised LNPs that can find applications as adhesives and alkaline stable LNPs . The entire process is based on a single-step solvent fractionation of lignin using either ethanol or ethyl acetate, subsequent functionalisation of selected fractions with epichlorohydrin, and recombination according to the original mass proportions in line with the so-called zero waste principle. Aqueous colloidal dispersions of lignins were synthesised by nanoprecipitation of epoxidised low molecular weight ( M W ) fractions combined with the corresponding unmodified high M W ones, and vice versa . Upon thermal treatment, LNPs containing the epoxidised insoluble fraction underwent intraparticle crosslinking, proving dimensional stability at pH 12. Conversely, LNPs including epoxidised solvent-soluble fractions resulted in interparticle crosslinking upon heating, which confirmed the surface localisation of such low M W fractions. The latter system was exploited to develop green LNP -based adhesives for aminated glass with lap shear strength outperforming prior adhesive systems based on lignin particles.