title: Development of Langmuir-Schaeffer cellulose nanocrystal monolayers and their interfacial behaviors.
abstract: Model cellulose surfaces based on cellulose nanocrystals (CNs) were prepared by the Langmuir-Schaeffer technique. Cellulose nanocrystals were obtained by acid hydrolysis of different natural fibers, producing rodlike nanoparticles with differences in charge density, aspect ratio, and crystallinity. Dioctadecyldimethylammonium bromide (DODA-Br) cationic surfactant was used to create CN-DODA complexes that allowed transfer of the CNs from the air/liquid interface in an aqueous suspension to hydrophobic solid substrates. Langmuir-Schaeffer horizontal deposition at various surface pressures was employed to carry out such particle transfer that resulted in CN monolayers coating the substrate. The morphology and chemical composition of the CN films were characterized by using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Also, their swelling behavior and stability after treatment with aqueous and alkaline solutions were studied using quartz crystal microgravimetry (QCM). Overall, it is concluded that the Langmuir-Schaeffer method can be used to produce single coating layers of CNs that were shown to be smooth, stable, and strongly attached to the solid support. The packing density of the films was controlled by selecting the right combination of surface pressure during transfer to the solid substrate and the amount of CNs available relative to the cationic charges at the interface.
authors.affiliation: Department of Forest Biomaterials, North Carolina State University, Raleigh, North Carolina 27695-8005, USA.
authors.forename: Youssef
authors.initials: Y
authors.lastname: Habibi
authors.forename: Ingrid
authors.initials: I
authors.lastname: Hoeger
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Kelley
authors.forename: Orlando J
authors.initials: OJ
authors.lastname: Rojas
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force; D008962:Models, Theoretical; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D056951:Photoelectron Spectroscopy; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D008567:Membranes, Artificial; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D002482:Cellulose