Impact resistance of nanocellulose films with bioinspired Bouligand microstructures

Xin Qin, Benjamin C. Marchi, Zhaoxu Meng, Sinan Keten*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The Bouligand structure features a helicoidal (twisted plywood) layup of fibers that are uniaxially arranged in-plane and is a hallmark of biomaterials that exhibit outstanding impact resistance. Despite its performance advantage, the underlying mechanisms for its outstanding impact resistance remain poorly understood, posing challenges for optimizing the design and development of bio-inspired materials with Bouligand microstructures. Interestingly, many bio-sourced nanomaterials, such as cellulose nanocrystals (CNCs), readily self-assemble into helicoidal thin films with inter-layer (pitch) angles tunable via solvent processing. Taking CNC films as a model Bouligand system, we present atomistically-informed coarse-grained molecular dynamics simulations to measure the ballistic performance of thin films with helicoidally assembled nanocrystals by subjecting them to loading similar to laser-induced projectile impact tests. The effect of pitch angle on the impact performance of CNC films was quantified in the context of their specific ballistic limit velocity and energy absorption. Bouligand structures with low pitch angles (18-42°) were found to display the highest ballistic resistance, significantly outperforming other pitch angle and quasi-isotropic baseline structures. Improved energy dissipation through greater interfacial sliding, larger in-plane crack openings, and through-thickness twisting cracks resulted in improved impact performance of optimal pitch angle Bouligand CNC films. Intriguingly, decreasing interfacial interactions enhanced the impact performance by readily admitting dissipative inter-fibril and inter-layer sliding events without severe fibril fragmentation. This work helps reveal structural and chemical factors that govern the optimal mechanical design of Bouligand microstructures made from high aspect ratio nanocrystals, paving the way for sustainable, impact resistant, and multi-functional films.

Original languageEnglish (US)
Pages (from-to)1351-1361
Number of pages11
JournalNanoscale Advances
Volume1
Issue number4
DOIs
StatePublished - 2019

Funding

The authors acknowledge funding from the Army Research Office (award #W911NF1710430), Office of Naval Research (PECASE Award, grant no. N00014-16-1-3175), and the Center for Hierarchical Materials Design (CHiMaD) funded by National Institute of Standards and Technology (award #70NANB14H012). Authors acknowledge support from the Dept. of Civil and Environmental Engineering and Dept. of Mechanical Engineering at Northwestern University, as well as supercomputing grants from Northwestern University High Performance Computing Center, Department of Defense High Performance Computing Modernization Program, and Argonne Leadership Computing Facility Director's Discretionary Program.

ASJC Scopus subject areas

  • General Chemistry
  • General Engineering
  • Bioengineering
  • Atomic and Molecular Physics, and Optics
  • General Materials Science

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