title: Aligned bioinspired cellulose nanocrystal-based nanocomposites with synergetic mechanical properties and improved hygromechanical performance.
abstract: Natural high-performance materials inspire the pursuit of ordered hard/soft nanocomposite structures at high fractions of reinforcements and with balanced supramolecular interactions. Such biomimetic design principles remain difficult to realize for bulk nanocomposites. Herein, we establish an effective drawing procedure that induces a high orientation of crystalline cellulose nanocrystals (CNCs) in a matrix of carboxymethylcellulose (CMC) at high level of reinforcements (50 vol %). We show such alignment in rather thick bulk films and report synergetic improvement with a simultaneous increase of stiffness, strength, and work-to-fracture as a function of the degree of alignment. Scanning electron microscopy and two-dimensional X-ray diffraction quantify the alignment of the cylindrical nanoparticles and link it to the extent of drawing and improvements in mechanical properties. We further show that the decline in mechanical properties of such waterborne all biobased nanocomposites at high relative humidity can be balanced using supramolecular modulation of the ionic interactions by exchanging the monovalent Na(+) counterion, present in CMC and CNC with di- or trivalent Cu(2+) and Fe(3+). This contribution demonstrates the importance of aligning one-dimensional reinforcements to achieve synergetic improvement in mechanical properties in sustainable bioinspired nanocomposites and suggests pathways to prepare water-stable materials based on a waterborne processing route.
authors: DWI-Leibniz-Institute for Interactive Materials, RWTH Aachen University , Forckenbeckstr. 50, 52056 Aachen, Germany.
authors: Baochun
authors: B
authors: Wang
authors: Jose Guillermo
authors: JG
authors: Torres-Rendon
authors: Jinchao
authors: J
authors: Yu
authors: Yumei
authors: Y
authors: Zhang
authors: Andreas
authors: A
authors: Walther
mesh_terms: D002266:Carboxymethylcellulose Sodium / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D053758:Nanoparticles / Q000737:chemistry; D013314:Stress, Mechanical; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D014867:Water; D002482:Cellulose; D002266:Carboxymethylcellulose Sodium
keywords: bioinspired materials; humidity; nanocellulose; toughness; wet-drawing