Nano- and Microtechnology from A - Z: From Nanosystems to Colloids and Interfaces

Introduction and Historical Evolution

Dispersions of one phase in another, such as glues and dyes, have been known to, and used by humans since circa 3000 to 2800 BC. However, systematic studies of dispersions as a classification of material did not occur until the late 1700s and early 1800s. In the late 1700s, Pierre Macquer studied the dispersions of finely divided gold particles in liquids, such as the gold tinctures of alchemy and medicine [1]. In the early 1800s, Thomas Graham studied the diffusion, osmotic pressure, and dialysis properties of a number of substances, including a variety of solutes dissolved in water (see References [2–4]). He noticed that some substances diffused quite quickly through parchment paper and animal membranes and formed crystals when dried. Other substances diffused only very slowly, if at all, through the parchment or membranes and apparently did not form crystals when dried. Graham proposed that the former group of substances, which included simple salts, be termed crystalloids, and that the latter group, which included albumen and gums, be termed colloids. Although colloidal dispersions had certainly been studied long before this time, and the alchemists frequently worked with body fluids, which are colloidal dispersions, Graham is generally regarded as having founded the discipline of colloid science.

The test of crystal formation later turned out to be too restrictive, the distinction of crystalloids versus colloids was dropped, and the ...