Registration Dossier

Diss Factsheets

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

Silicic acid, lithium magnesium sodium salt, commonly known as Laponite® commercially, is an inorganic layered silicate structure with a unit cell of the following composition

Na0.7+ [(Si8Mg5.5Li0.3) O20(OH)4]0.7-  

It is an inorganic synthetic version of hectorite clay, which commonly occurs in nature and is in the smectite group of clays, which includes bentonite.

It is available as a white odourless free flowing powder with a particle size in the 1 - 100 micron range. It has no measurable freezing point, melting point or boiling point. At temperatures above 1000 deg C it does not actually melt but sinters, at which point the layered structure is destroyed and the elements are converted to their oxides.

This substance does not dissolve in the water but forms a completely clear colloidal dispersion. The structure disperses to form disc-shaped crystals whose primary particle size is very small resulting in clear and colourless dispersions, invisible to the naked eye. At concentrations above 2% in water a clear gel is formed

The natural pH of Laponite® lies in the range 9.8 - 10.6 after dispersion in water at 2% w/w concentration. Studies showing the effect of pH on the stability of the dispersion demonstrate that this substance is stable between pH 4 and its natural pH and does not exhibit any dissociation or hydrolysis in this range. At pH 1-4 partial dissociation to the individual cations is observed.

This substance shows no flammable, explosive or oxidising properties