Controlling Impact Mitigation via Stimuli-Responsive Bouligand Nanostructures

Published

May 16, 2025

Author(s)

Sujin Lee, Katherine Evans, Jeremiah Woodcock, Jan Obrzut, Liping Huang, Christopher Soles, Edwin Chan

Abstract

Critical to their survival, natural organisms have developed exoskeletons that can withstand and inflict damage over their lifetime. The Bouligand structure of the exoskeleton plays a key role in toughness and damage resistance under external impacts. Numerous studies have studied the morphology of Bouligands and their mechanical properties, yet understanding their structure-function relationship remains challenging due to the complex mechanical responses of biological materials and the limitation of current characterization techniques. Motivated to elucidate the design principles of the natural Bouligand structure for impact mitigation, we conduct impact experiments on synthetic Bouligand films comprised of cellulose nanocrystals. By controlling the sonication conditions and evaporation rate of the cellulose nanocrystal suspensions, Bouligand films with controlled variations in pitch and thicknesses are generated. The impact performance and mechanical response of these materials are quantified using a microprojectile-based coefficient of restitution experiments and post-impact damage characterization. Our studies reveal two different energy dissipation mechanisms: plastic deformation and acoustic wave attenuation. The transition in mechanism is governed by film thickness, the helical pitch dimension, and the moisture content of the film.

Citation

Proceedings of the National Academy of Sciences

Pub Type

Journals

Download Paper

https://doi.org/10.1073/pnas.2425191122

Local Download

Keywords

Microballistic impact, mechanical properties, impact mitigation, nanocomposites

Citation

Lee, S. , Evans, K. , Woodcock, J. , Obrzut, J. , Huang, L. , Soles, C. and Chan, E. (2025), Controlling Impact Mitigation via Stimuli-Responsive Bouligand Nanostructures, Proceedings of the National Academy of Sciences, [online], https://doi.org/10.1073/pnas.2425191122, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958590 (Accessed October 20, 2025)