Fine dispersion of hydrophobic silicate platelets in anhydride-cured epoxy nanocomposites

Hydrophilic silicate platelets, prepared from the two-step process of exfoliation and extractive isolation of layered silicate clays, were allowed to react with an alkyl anhydride and convert, into organic-platelet hybrids of hydrophobic property. The exfoliative process was developed previously to isolate the silicate platelets of different sizes, including the platelets from the naturally occurring montmorillonite and synthetic fluorinated mica. The introduction of the hydrophobic organics through ionic exchanging with the sodium ions on the platelet surface (equivalent to SiO-Na+) was critical for rendering the silicate platelet in powder form and compatible with epoxy resin in curing into nanocomposites. The ultimate fine-dispersion of the hydrophobic platelets in epoxy matrices was observed by using transmission electron microscopy (TEM) and rendered the epoxies advanced high transparency, hardness, and particularly low coefficient of thermal expansion (CTE). The sustainable physical performance is suitable for the specific electronic applications such as encapsulation for light-emitting-diode devices.