title: Amphiphilic cellulose nanocrystals from acid-free oxidative treatment: physicochemical characteristics and use as an oil-water stabilizer.
abstract: A chemical pretreatment for producing cellulose nanocrystals (CNCs) with periodate oxidation and reductive amination is reported. This new functionalization of cellulose fibers dispenses an alternative method for fabricating individual CNCs without the widely used acid hydrolysis process. CNCs can be directly modified during the pretreatment step, and no additional post-treatments are required to tune the surface properties. Three butylamine isomers were tested to fabricate CNCs with amphiphilic features. After mechanical homogenization, CNCs occurred as individual crystallinities without aggregation where high uniformity in terms of shape and size was obtained. The elemental analysis and (1)H NMR measurement show that iso- and n-butylamine attach the highest number of butylamino groups to the cellulose fibers. Linking the alkyl groups increases the hydrophobic nature of the CNCs, where water contact angles from self-standing films up to 110.5° are reported. Since these butylamino-functionalized CNCs have hydrophobic characteristics in addition to the hydrophilic backbone of cellulose, the stabilization impact on oil/water emulsions is demonstrated as a potential application.
authors.affiliation: Fibre and Particle Engineering Laboratory and Thule Institute, ‡Fibre and Particle Engineering Laboratory, and §Department of Chemistry, University of Oulu , P.O. Box 4300, FI-90014, Finland.
authors.forename: Miikka
authors.initials: M
authors.lastname: Visanko
authors.forename: Henrikki
authors.initials: H
authors.lastname: Liimatainen
authors.forename: Juho Antti
authors.initials: JA
authors.lastname: Sirviö
authors.forename: Juha Pentti
authors.initials: JP
authors.lastname: Heiskanen
authors.forename: Jouko
authors.initials: J
authors.lastname: Niinimäki
authors.forename: Osmo
authors.initials: O
authors.lastname: Hormi
mesh_terms: D002082:Butylamines / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004655:Emulsions; D057927:Hydrophobic and Hydrophilic Interactions; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D013024:Soybean Oil / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D002082:Butylamines; D004655:Emulsions; D013501:Surface-Active Agents; D014867:Water; D013024:Soybean Oil; D002482:Cellulose; C032462:n-butylamine