2025-10-07 ノースカロライナ州立大学（NCState）
＜関連情報＞
- https://news.ncsu.edu/2025/10/nontoxic-solid-lubricant/
- https://www.cell.com/matter/abstract/S2590-2385(25)00517-X
グラフ理論に基づくバイオ由来固体潤滑剤 Graph theory-based bio-derived solid lubricant
Dhanush U. Jamadgni ∙ Paul Gregory ∙ Xiong Ye Xiao ∙ … ∙ Paul Bogdan ∙ Nicholas A. Kotov ∙ Martin Thuo
Matter Published:October 7, 2025
DOI:https://doi.org/10.1016/j.matt.2025.102474
Graphical abstract
Progress and potential
Complex particle flow governs efficiency in systems spanning agriculture, pharmaceuticals, and advanced manufacturing. Granular matter flow is complicated by particle clustering, jamming, and force-chain heterogeneity. In agriculture, for example, consistent seed flow is central to food security but is often compromised by reliance on toxic solid lubricants that are harmful to delicate ecosystems, pollinators, and farmers.
In this study, we demonstrate that combining graph theory, granular rheology, and tomographic imaging enables rational design of sustainable solid lubricants. These “network disruptors” redistribute stress within particle assemblies, mitigating convergence to a jammed state. Cellulose-based disruptors reduce friction, suppress clustering, and promote coherent flow by restructuring the underlying force networks. Future studies of this framework open opportunities for discovering new classes of network disruptors to enhance flow in diverse particle systems, with broad implications for construction, pharmaceuticals, and additive manufacturing.
Highlights
- Graph theory-inspired solid lubricants promote coherent granular particle flow
- Solid lubrications predominantly disrupt force chains rather than just reduction of friction
- Graph theory enables design of benign agricultural solid lubricant for improved seed flow
Summary
Granular matter processing necessitates fluidization for predictable and coherent flow. In agriculture, for example, toxic solid lubricants (talc or microplastics) are often deployed as fluency agents, contaminating fragile (e.g., waterways) or precious (e.g., farmlands or pollinators) ecosystems. We applied graph theory to design bio-derived fluency agents with seeds as a model system of complex granular matter. Adopting graph theory, we evaluated multibody effects and transient clustering in 2D and 3D motion of seeds. Time-dependent graph characteristics (e.g., Ollivier-Ricci curvature, fractality, and multifractal spectrum) reveal that modified cellulose-derived lubricants effectively disrupt clustering and enhance seed flow. Flow energy trends support graph-based inferences and confirm improved coherent flow. Lubricity was confirmed with a stationary seed metering system and field trials. The developed materials are biodegradable, sustainable, and field-deployable replacements of current toxic products.
