Effect of montmorillonite on properties of nanocomposite coatings

Unmodified or chemically modified montmorillonite (MMT) dispersed in water was added into the reaction mixture forming hybrid organic–inorganic (O–I) nanocomposite coating. Two basic systems made from functionalised trialkoxysilane and oligomeric diamine v. functionalised dialkoxysilane and triamine were prepared and compared. End properties depend not only on the concentration and kind of MMT used but also on the inner constitution of the O–I matrix. Already 1 wt-% of unmodified MMT influences considerably surface and mechanical properties, but the effect of chemically modified MMT is not so pronounced. This can be due to worse dispersion (scattering) of chemically modified MMT within the O–I matrix compared with unmodified one: while unmodified MMT is partially intercalated, partially exfoliated in the product, substantial amount of original, unaffected MMT clusters was found there. Solid state nuclear magnetic resonance spectroscopy confirmed the interaction of MMT platelets with the O–I matrix.