title: Generating in-Plane Orientational Order in Multilayer Films Prepared by Spray-Assisted Layer-by-Layer Assembly.
abstract: We present a simple yet efficient method for orienting cellulose nanofibrils in layer-by-layer assembled films through spray-assisted alignment. While spraying at 90° against a receiving surface produces films with homogeneous in-plane orientation, spraying at smaller angles causes a macroscopic directional surface flow of liquid on the receiving surface and leads to films with substantial in-plane anisotropy when nanoscale objects with anisotropic shapes are used as components. First results with cellulose nanofibrils demonstrate that such fibrils are easily aligned by grazing incidence spraying to yield optically birefringent films over large surface areas. We show that the cellulosic nanofibrils are oriented parallel to the spraying direction and that the orientational order depends for example on the distance of the receiving surface from the spray nozzle. The alignment of the nanofibrils and the in-plane anisotropy of the films were independently confirmed by atomic force microscopy, optical microscopy between crossed polarizers, and the ellipsometric determination of the apparent refractive index of the film as a function of the in-plane rotation of the sample with respect to the plane of incidence of the ellipsometer.
authors.affiliation: CNRS Institut Charles Sadron , 23 Rue du Loess, F-67034 Strasbourg, France.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Blell
authors.affiliation: CNRS Institut Charles Sadron , 23 Rue du Loess, F-67034 Strasbourg, France.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Lin
authors.affiliation: Innventia AB , Drottning Kristinas väg 61, Box 5604, SE-114 86 Stockholm, Sweden.
authors.forename: Tom
authors.initials: T
authors.lastname: Lindström
authors.affiliation: Innventia AB , Drottning Kristinas väg 61, Box 5604, SE-114 86 Stockholm, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Ankerfors
authors.affiliation: CNRS Institut Charles Sadron , 23 Rue du Loess, F-67034 Strasbourg, France.|Faculté de Chimie, Université de Strasbourg , 1 Rue Blaise Pascal, F-67008 Strasbourg, France.
authors.forename: Matthias
authors.initials: M
authors.lastname: Pauly
authors.affiliation: CNRS Institut Charles Sadron , 23 Rue du Loess, F-67034 Strasbourg, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Felix
authors.affiliation: CNRS Institut Charles Sadron , 23 Rue du Loess, F-67034 Strasbourg, France.|Faculté de Chimie, Université de Strasbourg , 1 Rue Blaise Pascal, F-67008 Strasbourg, France.|International Center for Frontier Research in Chemistry , 8 Allée Gaspard Monge, F-67083 Strasbourg, France.
authors.forename: Gero
authors.identifier: 0000-0002-7976-8818
authors.initials: G
authors.lastname: Decher
keywords: anisotropic materials; cellulose nanofibrils; in-plane orientation; layer-by-layer assembly; polyelectrolyte multilayers; spray-assisted alignment