Colloidal network formation and evolution during gelation and coarsening

The gelation of attractive colloidal particles forms a space-spanning network, transforming a fluid-like suspension into a viscoelastic solid. The process begins with the formation of reversible particle-particle bond formation, characterized by interaction energy and percolation of the particulate structure, followed by long-term structure coarsening. Understanding these steps in this second-order phase transition is crucial for optimizing gel properties. However, pinpointing precise transition points remains a significant research gap. Using network science tools, we analyze the structural evolution during gelation. Findings indicate that the critical percolation point, marking the first transition phase, can be accurately estimated through network diameter analysis. This is in contrast with the modulus measurements that may or may not be able to pinpoint the percolation transition. Additionally, particle-level characteristics, like coordination number, exhibit distinct transitions before and after coarsening. This differentiation enables a clear identification of the initial sol-gel transition from the subsequent stage of maturation and coarsening. Additionally, we offer a comprehensive comparative analysis across varying attraction strength levels and volume fractions.