title: Bioinspired Mechanical Gradients in Cellulose Nanofibril/Polymer Nanopapers.
abstract: Mechanical gradients are important as tough joints, for strain field engineering in printable electronics, for actuators, and for biological studies, yet they are difficult to prepare and quantitatively characterize. We demonstrate the additive fabrication of gradient bioinspired nanocomposites based on stiff, renewable cellulose nanofibrils that are bottom-up toughened via a tailor-made copolymer. Direct filament writing of different nanocomposite hydrogels in patterns, and subsequent healing of the filaments into continuous films while drying leads to a variety of linear, parabolic and striped bulk gradients. In situ digital image correlation under tensile deformation reveals important differences in the strain fields regarding asymmetry and step heights of the patterns. We envisage that merging top-down and bottom-up structuring of nanocellulose hybrids opens avenues for aperiodic and multiscale, bioinspired nanocomposites with optimized combinations of stiffness and toughness.
authors.affiliation: DWI-, Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany.
authors.forename: Baochun
authors.initials: B
authors.lastname: Wang
authors.affiliation: DWI-, Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany.
authors.forename: Alejandro J
authors.initials: AJ
authors.lastname: Benitez
authors.affiliation: DWI-, Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany.
authors.forename: Francisco
authors.initials: F
authors.lastname: Lossada
authors.affiliation: DWI-, Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany.
authors.forename: Remi
authors.initials: R
authors.lastname: Merindol
authors.affiliation: DWI-, Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany. walther@dwi.rwth-aachen.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Walther
keywords: 3D printing; bioinspired nanocomposites; gradient materials; nanocellulose; self-assembly