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). The network gives the material an elasticity: a solid-like property [1, p. 95].

The composition of the sub-units and the bonds between them strongly affect properties of the gel. [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

You can witness the sol-gel transition by curing epoxy [1], making a dessert with gelatin [ 2 ], or making jam with pectin [ 3 ].

References

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

[2] B. Cole, "Gelatin," http://www.gelatin.co.za/gltn1.html, (accessed Nov. 4, 2009).

[3] S. Bowling, "On the Jelling of Jelly," Alaska Science Forum, http://www.gi.alaska.edu/ScienceForum/ASF8/887.html, (Aug. 20, 1988).