title: Adsorption of Xyloglucan onto Cellulose Surfaces of Different Morphologies: An Entropy-Driven Process.
abstract: The temperature-dependence of xyloglucan (XG) adsorption onto smooth cellulose model films regenerated from N-methylmorpholine N-oxide (NMMO) was investigated using surface plasmon resonance spectroscopy, and it was found that the adsorbed amount increased with increasing temperature. This implies that the adsorption of XG to NMMO-regenerated cellulose is endothermic and supports the hypothesis that the adsorption of XG onto cellulose is an entropy-driven process. We suggest that XG adsorption is mainly driven by the release of water molecules from the highly hydrated cellulose surfaces and from the XG molecules, rather than through hydrogen bonding and van der Waals forces as previously suggested. To test this hypothesis, the adsorption of XG onto cellulose was studied using cellulose films with different morphologies prepared from cellulose nanocrystals (CNC), semicrystalline NMMO-regenerated cellulose, and amorphous cellulose regenerated from lithium chloride/dimethylacetamide. The total amount of high molecular weight xyloglucan (XGHMW) adsorbed was studied by quartz crystal microbalance and reflectometry measurements, and it was found that the adsorption was greatest on the amorphous cellulose followed by the CNC and NMMO-regenerated cellulose films. There was a significant correlation between the cellulose dry film thickness and the adsorbed XG amount, indicating that XG penetrated into the films. There was also a correlation between the swelling of the films and the adsorbed amounts and conformation of XG, which further strengthened the conclusion that the water content and the subsequent release of the water upon adsorption are important components of the adsorption process.
authors.affiliation: Department of Fibre and Polymer Technology and Wallenberg Wood Science Center, KTH Royal Institute of Technology , 100 44 Stockholm, Sweden.
authors.forename: Tobias
authors.initials: T
authors.lastname: Benselfelt
authors.affiliation: Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada.
authors.forename: Emily D
authors.initials: ED
authors.lastname: Cranston
authors.affiliation: Department of Pulp and Paper Technology, Karadeniz Technical University , 61080 Trabzon, Turkey.
authors.forename: Sedat
authors.initials: S
authors.lastname: Ondaral
authors.affiliation: Cellutech AB, 114 28 Stockholm, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Johansson
authors.affiliation: The Michael Smith Laboratories and the Department of Chemistry, The University of British Columbia , Vancouver, British Columbia V6T 1Z4, Canada.
authors.forename: Harry
authors.initials: H
authors.lastname: Brumer
authors.affiliation: Surface and Corrosion Science, KTH Royal Institute of Technology , 100 44 Stockholm, Sweden.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Rutland
authors.affiliation: Department of Fibre and Polymer Technology and Wallenberg Wood Science Center, KTH Royal Institute of Technology , 100 44 Stockholm, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Wågberg
mesh_terms: D000327:Adsorption; D002482:Cellulose / Q000737:chemistry*; D019277:Entropy; D005936:Glucans / Q000737:chemistry*; D006860:Hydrogen Bonding; D018625:Microscopy, Atomic Force; D053758:Nanoparticles / Q000737:chemistry*; D058525:Quartz Crystal Microbalance Techniques; D020349:Surface Plasmon Resonance; D014867:Water / Q000737:chemistry*; D014990:Xylans / Q000737:chemistry*
chemical_list: D005936:Glucans; D014990:Xylans; D014867:Water; C029353:xyloglucan; D002482:Cellulose