Particle shape tunes fragility in hard polyhedron glass-formers. Issue 3 (17th November 2020)

• Record Type: Journal Article
• Authors: Teich, Erin G.; van Anders, Greg; Glotzer, Sharon C.
• Is Part Of: Soft matter. Volume 17:Issue 3(2021)
• Page Start: 600
• Page End: 610
• Publication Date: 2020-11-17
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/d0sm01067g
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : More tetrahedral particle shapes make less fragile hard particle glass-formers, as evidenced by the density-dependent slope of the log of relaxation time, s ( ϕ / ϕ C ) ≡ ∂ log τ α /∂( ϕ / ϕ C ). Abstract : We demonstrate that fragility, a technologically relevant characteristic of glass formation, depends on particle shape for glass-formers comprised of hard polyhedral particles. We find that hard polyhedron glass-formers become stronger (less fragile) as particle shape becomes increasingly tetrahedral. We correlate fragility with local structure, and show that stronger systems display a stronger preference for a pairwise face-to-face motif that frustrates global periodic ordering and gives rise in most systems studied to bond angle distributions that are peaked around the ideal tetrahedral bond angle. We demonstrate through mean-field-like simulations of explicit particle pairs and surrounding baths of "ghost" particles that the prevalence of this pairwise configuration can be explained via free volume exchange and emergent entropic force arguments. Our study provides a clear and direct link between the local geometry of fluid structure and the properties of glass formation, independent of interaction potential or other non-geometric tuning parameters. We ultimately demonstrate that the engineering of fragility in colloidal systems via slight changes to particle shape is possible.