title: A method for the heterogeneous modification of nanofibrillar cellulose in aqueous media.
abstract: Cellulosic substrates were modified by using sequential adsorption of functionalized carboxymethyl cellulose (CMC) and "click" chemistry in aqueous media. First, the effect of degree of substitution (DS), and level of functionalization as well as ionic strength of the medium were systematically investigated in situ by using quartz crystal microbalance with dissipation (QCM-D) in terms of the extent of adsorption of propargyl and azido functionalized CMC. It was found that the functionalization of CMC did not prevent its adsorption on cellulose. However, it was only effective in the presence of electrolytes. Moreover, the adsorption was found to be more efficient for the functionalized CMCs with low initial DS. Next, "click" chemistry, copper (I)-catalyzed azide-alkyne cycloaddition reaction (CuAAC), was carried out for covalent attachment of different molecules on the pre-functionalized ultrathin cellulose films. The modified cellulosic surfaces were further characterized using AFM imaging and XPS. Finally, the method was successfully used in modification of nanofibrillar cellulose (NFC) in aqueous media.
authors.affiliation: Aalto University School of Chemical Technology, Department of Forest Products Technology, P.O. Box 16300, 00076 Aalto, Finland. Electronic address: karoliina.junka@aalto.fi.
authors.forename: Karoliina
authors.initials: K
authors.lastname: Junka
authors.forename: Ilari
authors.initials: I
authors.lastname: Filpponen
authors.forename: Leena-Sisko
authors.initials: LS
authors.lastname: Johansson
authors.forename: Eero
authors.initials: E
authors.lastname: Kontturi
authors.forename: Orlando J
authors.initials: OJ
authors.lastname: Rojas
authors.forename: Janne
authors.initials: J
authors.lastname: Laine
mesh_terms: D000327:Adsorption; D000818:Animals; D001386:Azides / Q000737:chemistry; D002266:Carboxymethylcellulose Sodium / Q000737:chemistry; D002417:Cattle; D002482:Cellulose / Q000737:chemistry*; D057930:Click Chemistry; D057139:Nanofibers / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D001386:Azides; D014867:Water; D012710:Serum Albumin, Bovine; D002482:Cellulose; D002266:Carboxymethylcellulose Sodium
keywords: Adsorption; Carboxymethyl cellulose; Click chemistry; Functional materials; Nanofibrillar cellulose; Surface functionalization