title: Polyelectrolyte adsorption on thin cellulose films studied with reflectometry and quartz crystal microgravimetry with dissipation.
abstract: Thin cellulose films were prepared by dissolving carboxymethylated cellulose fibers in N-methyl morpholine oxide and forming thin films on silicon wafers by spin-coating. The adsorption of cationic polyacrylamides and polydiallyldimethylammonium chloride onto these films was studied by stagnation point adsorption reflectometry (SPAR) and by quartz crystal microgravimetry with dissipation (QCM-D). The polyelectrolyte adsorption was studied by SPAR as a function of salt concentration, and it was found that the adsorption maximum was located at 1 mM NaCl for polyelectrolytes of low charge density and at 10 mM NaCl for polyelectrolytes of high charge density. Electrostatic screening led to complete elimination of the polyelectrolyte adsorption at salt concentrations of 300 mM NaCl. According to the QCM-D analysis, the cellulose films showed a pronounced swelling in water that took several hours to complete. Subsequent adsorption of polyelectrolytes onto the cellulose films led to a release of water from the cellulose, an effect that was substantial for polyelectrolytes of high charge density at low salt concentrations. The total mass change including water could therefore show either an increase or a decrease during adsorption onto the cellulose films, depending on the experimental conditions.
authors.affiliation: Department of Fibre and Polymer Technology, The Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Lars-Erik
authors.initials: LE
authors.lastname: Enarsson
authors.forename: Lars
authors.initials: L
authors.lastname: Wågberg
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000327:Adsorption; D002482:Cellulose / Q000138:chemical synthesis / Q000737:chemistry*; D003460:Crystallization; D004573:Electrolytes / Q000737:chemistry*; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008567:Membranes, Artificial; D008839:Microelectrodes; D011095:Polyethylenes / Q000737:chemistry*; D011791:Quartz / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D055672:Static Electricity; D013499:Surface Properties; D013997:Time Factors; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D002482:Cellulose; D004573:Electrolytes; D046911:Macromolecular Substances; D008567:Membranes, Artificial; D011095:Polyethylenes; D011791:Quartz; D000644:Quaternary Ammonium Compounds; D012822:Silicon Dioxide; D012965:Sodium Chloride; D000099166:Polyacrylamides; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride