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Colloidal gelation phase diagram has been traditionally characterized using three key factors: particle volume fraction, strength of attraction, and range of attraction. While there's a rich body of literature on the role of attraction strength and particle volume fraction, majority of studies have been limited to short range interactions. Using Brownian dynamics simulations, we explored the effect that the range of attractions has on the microstructure and dynamics of both weakly and strongly attractive colloidal systems. Although gelation occurs significantly faster at high attraction strength, by an order of magnitude compared to low strength, we did not observe any clear trend in gelation-rate with respect to a change in the range of interaction. However, as the attraction range increases in both systems, the final structure undergoes a transition from a single connected network to a fluid of dense clusters. This results in a new gelation phase boundary for long range attractive colloids.
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This content will become publicly available on October 22, 2026
Emergence and evolution of a particulate network during gelation and coarsening of attractive colloids
The process of gelation in attractive colloids involves formation of an interconnected and percolated network, followed by its coarsening and maturation. In this study, we analyze the formation and evolution of this particulate network and introduce deterministic quantitative measures to evaluate the key transition points. The rate of change in the number of colloidal clusters before and after percolation can be directly used to identify gelation as a continuous second order phase transition. Simultaneously the diameter of the particle network exhibits a distinguishable maxima, marking the precise moment of percolation transition. However, local measures of the structure such as coordination number do not reflect on the percolation. Alternatively, accumulative number of unique particle contacts can be used to indicate the long time coarsening of the particulate structure. Global structural measures such as Voronoi volume distribution and its changes over time can also be used to distinctly mark these two regimes. Finding a consistent behavior across varying attraction strength levels and volume fractions of colloids, we propose that percolation and coarsening of the particulate gels can be viewed as two distinct transitions with clearly distinguishable structural demarcations.
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- Award ID(s):
- 2104869
- PAR ID:
- 10652099
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 21
- Issue:
- 41
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 7904 to 7916
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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