title: Cellulose nanofibril-based multilayered thin films: effect of ionic strength on porosity, swelling, and optical properties.
abstract: TEMPO-oxidized cellulose nanofibrils (CNF) and synthetic poly(allylamine) hydrochloride (PAH) were used to build multilayered thin films via the dipping-assisted layer-by-layer technique. We used the ionic strength, in both CNF suspension and PAH solution, as a key parameter to control the structure of the films. Three systems with different ionic strength parameters were investigated. We studied the growth of the films and their surface morphology by ellipsometry and AFM and investigated their porosity and swelling behavior using neutron reflectivity. Our results showed that the PAH conformation is a determining factor not only for film growth but also for structural properties: with salt-free PAH solution where chains have extended conformation, the resulting films have lower porosity and higher swelling ratios, compared to the ones made using high ionic strength (1 M) PAH solution, where chains have a coiled conformation. The slight aggregation of CNF, induced by adding a small amount of salt (12 mM), has less influence on film growth and porosity, whereas it has a greater impact on swelling. The origin of these differences is discussed. The structure of the films obtained was linked to their optical properties and, in particular, to their antireflective character.
authors: UR1268 Biopolymères Interactions Assemblages, INRA , 44316 Nantes, France.
authors: Firas
authors: F
authors: Azzam
authors: Céline
authors: C
authors: Moreau
authors: Fabrice
authors: F
authors: Cousin
authors: Alain
authors: A
authors: Menelle
authors: Hervé
authors: H
authors: Bizot
authors: Bernard
authors: B
authors: Cathala
mesh_terms: D000499:Allylamine / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry; D057139:Nanofibers / Q000737:chemistry*; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D016062:Porosity
chemical_list: D003497:Cyclic N-Oxides; D000499:Allylamine; D002482:Cellulose; C003959:TEMPO