Network physics of attractive colloidal gels: Resilience, rigidity, and phase diagram

• 成果类型: Article
• 署名作者: Nabizadeh, Mohammad; Nasirian, Farzaneh; Li, Xinzhi; Saraswat, Yug; Waheibid, Rony; Hsiao, Lilian C.; Bi, Dapeng; Ravandi, Babak; Jamali, Safa
• 署名单位: Northeastern University; Northeastern University; Northeastern University; Carnegie Mellon University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9154
• DOI: 10.1073/pnas.2316394121
• 发表日期: 2024-01-16
• 关键词: scaling behavior; community structure; complex networks; rheology; microstructure; isostaticity; suspensions; elasticity; TRANSITION; particles

摘要

Colloidal gals exhibit solid-like behavior at vanishingly small fractions of solids, owing to ramified space-spanning networks that form due to particle-particle interactions. These networks give the gel its rigidity, and with stronger attractions the elasticity grows as well. The emergence of rigidity can be described through a mean field approach; nonetheless fundamental understanding of how rigidity varies in gels of different attractions is lacking. Moreover, recovering an accurate gelation phase diagram based on the system's variables has been an extremely challenging task. Understanding the nature of colloidal clusters, and how rigidity emerges from their connections is key to controlling and designing gels with desirable properties. Here, we employ network analysis tools to interrogate and characterize the colloidal structures. We construct a particle-level network, having all the spatial coordinates of colloids with different attraction levels, and also identify polydisperse rigid fractal clusters using a Gaussian mixture model, to form a coarse-grained cluster network that distinctly shows main physical features of the colloidal gels. A simple mass-spring model then is used to recover quantitatively the elasticity of colloidal gels from these cluster networks. Interrogating the resilience of these gel networks shows that the elasticity of a gel (a dynamic property) is directly correlated to its cluster network's resilience (a static measure). Finally, we use the resilience investigations to devise [and experimentally validate] a fully resolved phase diagram for colloidal gelation, with a clear solid-liquid phase boundary using a single volume fraction of particles well beyond this phase boundary.