Jun 3 2019
Not everyone may be familiar with the term colloidal gel. However, the majority of people come across these materials daily.
Several pharmaceuticals, cosmetics, food products, and even building materials are composed of colloidal gels, and thus, these materials are extensively investigated. However, until now, research techniques have not been able to follow the entire gelation process. At present, scientists at The University of Tokyo have employed confocal microscopy to analyze the process in real time with single particle resolution. The study outcomes have been reported in Science Advances.
Colloidal gels comprise of two phases that are entangled with one another: a solid particle network and a liquid solvent. The outcome is soft-solid materials with distinctive properties, such as mechanical stability and elasticity, which make them appealing choices for a number of applications. These properties have been capitalized upon commercially; however, they are not totally explained by the theoretical insights that have been gained so far.
Studying colloidal gels that are already formed means that the actual process of gelation remains somewhat of a black box.
Hideyo Tsurusawa, Study Lead Author, University of Tokyo
By establishing a method that allows us to follow the kinetics of the complete gelation process, we have gained new insight into the origins of the characteristic properties of colloidal gels. Understanding the individual stages of gelation has enabled us to demonstrate a direct link between the mechanical stability of gels and isostatic structures.
Mathieu Leocmach, Study Lead Author, University of Tokyo
Isostatic structures are clusters or particles that suffer balanced forces. The scientists identified that the point in the gelation process when solidity occurs represents the point of isotropic percolation of isostatic structures through the gel. Their comparison of the differences in percolation behavior between low and high concentration gels indicated that the space-spanning percolations of isostatic structures are directly associated with mechanical stability.
The real time nature and resolution of our technique have resulted in a depth of understanding that was not previously achievable. We hope that the enhanced insight will be useful for researchers working to address complex mechanical and rheological issues across the wide span of colloidal gel applications.
Hajime Tanaka, Study Corresponding Author, University of Tokyo