Sol-Gel Transition

Definition

The sol-gel transition (also known as gelation) is simply a change from a liquid state to a gel state. In the liquid state, components dispersed in the liquid are relatively free to move about. In the gel state, these sub-units bond together to form a network extending throughout the whole substance (see figure 1). This network gives the material an elasticity: a solid-like property [1, p. 95].

The nature of the sub-units and the bonds between play an important role in the properties of the gel formed. [1, p. 95].

Figure 1. This cartoon shows the free-floating subunits in the sol (liquid) state, and the network formed in the gel state. *From Wikimedia Commons

Examples

Some examples of sol-gel transitions you may witness are the curing of epoxy [1], the gelling of Jell-O ( ), and the gelation of Jam (Pectin).

http://www.gi.alaska.edu/ScienceForum/ASF8/887.html http://www1.lsbu.ac.uk/water/hypec.html#fun

References

[1] R. Jones, "Soft Condensed Matter," Oxford University Press Inc., New York (2002).