title: Structural and Energetic Studies on the Interaction of Cationic Surfactants and Cellulose Nanocrystals.
abstract: We report a comprehensive study on the interactions between cationic surfactant homologues CnTAB (n = 12, 14, and 16) with negatively charged cellulose nanocrystals (CNCs). By combining different techniques, such as isothermal titration calorimetry (ITC), surface tension, light scattering, electrophoretic mobility, and fluorescence anisotropy measurements, we identified two different driving forces for the formation of surface induced micellar aggregates. For the C12TAB surfactant, a surfactant monolayer with the alkyl chains exposed to the water is formed via electrostatic interactions at low concentration. At a higher surfactant concentration, micellar aggregates are formed at the CNC surface. For the C14TAB and C16TAB systems, micellar aggregates are formed at the CNC surface at a much lower surfactant concentration via electrostatic interactions, followed by hydrophobic interactions between the alkyl chains. At higher surfactant concentration, charge neutralization and association of the surfactant decorated CNC aggregates led to flocculation.
authors.affiliation: Institute of Chemistry - Universidade Estadual de Campinas (UNICAMP) , CP 6154, CEP 13083-970, Campinas, SP Brazil.
authors.forename: César
authors.initials: C
authors.lastname: Brinatti
authors.affiliation: Department of Chemical Engineering, Waterloo Institute for Nanotechnology University of Waterloo , 200 University Avenue West, Ontario N2L 3G1, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Huang
authors.affiliation: CelluForce Inc. , 625, Président-Kennedy Avenue, Montreal, Quebec H3A 1K2, Canada.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Berry
authors.affiliation: Department of Chemical Engineering, Waterloo Institute for Nanotechnology University of Waterloo , 200 University Avenue West, Ontario N2L 3G1, Canada.
authors.forename: Kam C
authors.initials: KC
authors.lastname: Tam
authors.affiliation: Institute of Chemistry - Universidade Estadual de Campinas (UNICAMP) , CP 6154, CEP 13083-970, Campinas, SP Brazil.
authors.forename: Watson
authors.initials: W
authors.lastname: Loh
mesh_terms: D002151:Calorimetry; D002482:Cellulose / Q000737:chemistry*; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D005454:Fluorescence Polarization; D057927:Hydrophobic and Hydrophilic Interactions; D008823:Micelles; D053758:Nanoparticles / Q000737:chemistry*; D055672:Static Electricity; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D002593:Cetrimonium Compounds; D008823:Micelles; D013501:Surface-Active Agents; D014867:Water; D002482:Cellulose; D000077286:Cetrimonium