Self-assembly of defined core–shell ellipsoidal particles at liquid interfaces

Eatson, Jack; Bauernfeind, Susann; Midtvedt, Benjamin; Ciarlo, Antonio; Menath, Johannes; Pesce, Giuseppe; Schofield, Andrew B.; Volpe, Giovanni; Clegg, Paul S.; Vogel, Nicolas; Buzza, D. Martin A.; Rey, Marcel

Abstract

Hypothesis: Ellipsoidal particles confined at liquid interfaces exhibit complex self-assembly due to quadrupolar capillary interactions, favouring either tip-to-tip or side-to-side configurations. However, predicting and controlling which structure forms remains challenging. We hypothesize that introducing a polymer-based soft shell around the particles will modulate these capillary interactions, providing a means to tune the preferred self-assembly configuration based on particle geometry and shell properties. Experiments: We fabricate core–shell ellipsoidal particles with defined aspect ratios and shell thickness through thermo-mechanical stretching. Using interfacial self-assembly experiments, we systematically explore how aspect ratio and shell thickness affect the self-assembly configurations. Monte Carlo simulations and theoretical calculations complement the experiments by mapping the phase diagram of thermodynamically preferred structures as a function of core–shell properties. Findings: Pure ellipsoidal particles without a shell consistently form side-to-side “chain-like” assemblies, regardless of aspect ratio. In contrast, core–shell ellipsoidal particles exhibit a transition from tip-to-tip “flower-like” arrangements to side-to-side structures as aspect ratio increases. The critical aspect ratio for this transition shifts with increasing shell thickness. Our results highlight how we can engineer the self-assembly of anisotropic particles at liquid interfaces by tuning their physicochemical properties such as aspect ratio and shell thickness, allowing the deterministic realization of distinct structural configurations.

Citation

Eatson, J., Bauernfeind, S., Midtvedt, B., Ciarlo, A., Menath, J., Pesce, G., Schofield, A. B., Volpe, G., Clegg, P. S., Vogel, N., Buzza, D. M. A., & Rey, M. (2025). Self-assembly of defined core–shell ellipsoidal particles at liquid interfaces. Journal of colloid and interface science, 683, pt.2, 435-446. https://doi.org/10.1016/j.jcis.2024.12.156

• Journal Article Type: Article
• Acceptance Date: Jan 19, 2024
• Online Publication Date: Dec 21, 2024
• Publication Date: Apr 1, 2025
• Deposit Date: Jan 6, 2025
• Publicly Available Date: Jan 6, 2025
• Journal: Journal of Colloid and Interface Science
• Print ISSN: 0021-9797
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 683, pt.2
• Pages: 435-446
• DOI: https://doi.org/10.1016/j.jcis.2024.12.156
• Keywords: Core-shell polymeric ellipsoidal particles; Self-assembly; Capillary interactions; Anisotropic particle; Liquid interfaces; Phase behaviour
• Public URL: https://hull-repository.worktribe.com/output/5001329