Magnesium hydroxide nanoparticles are made from a magnesium compound that
is reacted with an organic dispersing agent (e.g., a hydroxy acid) to
form an intermediate magnesium compound. Magnesium hydroxide
nanoparticles are formed from hydrolysis of the intermediate compound.
The bonding between the organic dispersing agent and the magnesium during
hydrolysis influences the size of the magnesium hydroxide nanoparticles
formed therefrom. The magnesium hydroxide nanoparticles can be treated
with an aliphatic compound (e.g., a monofunctional alcohol) to prevent
aggregation of the nanoparticles during drying and/or to make the
nanoparticles hydrophobic such that they can be evenly dispersed in a
polymeric material. The magnesium hydroxide nanoparticles exhibit
superior fire retarding properties in polymeric materials compared to
known magnesium hydroxide particles.