title: Anionically Stabilized Cellulose Nanofibrils through Succinylation Pretreatment in Urea-Lithium Chloride Deep Eutectic Solvent.
abstract: Deep eutectic solvents (DESs) are green chemicals that have the potential to replace traditional solvents in chemical reactions. In this study, urea-LiCl DES was used successfully as a reaction medium in the anionic functionalization of wood cellulose with succinic anhydride. The effects of reaction temperature and time on the carboxyl content and yield were evaluated. The analyses of the degree of polymerization and crystallinity revealed that the DES was a nondegrading and nondissolving reaction medium. Three samples with the highest carboxyl contents were further nanofibrillated with a microfluidizer to diameters of 2-7 nm, as observed by atomic force microscopy. Samples treated at 70-80 °C for 2 h gave the best outcome and resulted in highly viscose and transparent gels. The sample treated at 90 °C contained larger nanoparticles and larger aggregates owing to the occurrence of possible side reactions but resulted in better thermal stability.
authors.affiliation: Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Finland.
authors.forename: Tuula
authors.identifier: http://orcid.org/0000-0001-8575-5848
authors.initials: T
authors.lastname: Selkälä
authors.affiliation: Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Finland.
authors.forename: Juho Antti
authors.identifier: http://orcid.org/0000-0002-7404-3340
authors.initials: JA
authors.lastname: Sirviö
authors.affiliation: Microelectronics Research Unit, University of Oulu, P.O. Box 4500, FI-90014, Finland.
authors.forename: Gabriela S
authors.identifier: http://orcid.org/0000-0002-6530-5281
authors.initials: GS
authors.lastname: Lorite
authors.affiliation: Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Finland.
authors.forename: Henrikki
authors.identifier: http://orcid.org/0000-0002-7911-2632
authors.initials: H
authors.lastname: Liimatainen
mesh_terms: D000838:Anions; D002482:Cellulose / Q000737:chemistry*; D055772:Green Chemistry Technology / Q000379:methods*; D018021:Lithium Chloride; D049329:Nanostructures / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013387:Succinic Anhydrides / Q000737:chemistry; D014508:Urea
chemical_list: D000838:Anions; D012997:Solvents; D013387:Succinic Anhydrides; C031801:succinic anhydride; D014508:Urea; D002482:Cellulose; D018021:Lithium Chloride
keywords: biomass; carbohydrates; gels; nanostructures; solvent effects