The influence of nanoadditives on surface, permeability and mechanical properties of self-organized organic–inorganic nanocomposite coatings

Abstract

Transparent and colorless nanocomposite coatings were prepared from a hybrid organicinorganic matrix and several inorganic nanofillers. The products are characterized by a high degree of self-assembling of the matrix which was prepared from an epoxy-functional organosilicon precursor and an oligomeric diamine. Unmodified and chemically modified montmorillonite, bentonite, laponite, and colloidal silica were used as nanofillers, differing in shape, size, and origin. The nanoadditive concentration in coatings was always 0.5 wt%. Solid-state NMR ( 13 C and 29 Si CP/MAS) spectroscopy was used for estimation of polyaddition and polycondensation degree in the polymer matrix in order to evaluate its structure changes caused by interaction with the nanoadditives. The influence of the kind of additive on the dynamic mechanical properties, gas permeability, and surface properties (topography, roughness) is discussed.

The role of organic modification of layered nanosilicates on mechanical and surface properties of organic–inorganic coatings

“…In recent studies by the authors, [26][27][28] we have shown that the polymers D and T provide suitable matrices for the fabrication of low-loaded clay-containing nanocomposites. We found that very small amounts of layered silicates, e.g., 0.5 wt% provoke significant changes in mechanical properties and gas permeability.…”

“…We found that very small amounts of layered silicates, e.g., 0.5 wt% provoke significant changes in mechanical properties and gas permeability. 27 Scheme 3 shows the layered structure of the silicates of the montmorillonite type. Two thin silicate layers [Si 2 O 5 2À ] ¥ are connected mostly by magnesium cations and form a thicker rigid montmorillonite layer.…”

“…As nanofiller, colloidal silica (in concentrations from 0.5 to 20 wt% [24][25][26][27] ) and unmodified and several chemically modified montmorillonites at concentrations ranging from 0.5 to 5 wt% [26][27][28] were used. The previous study by the authors 27 was aimed at studying the effect of small amounts of inorganic nanofillers on the nanocomposite properties.…”

“…Promising results were obtained, and strong compatibilizer effects-in spite of very small amounts-on the overall properties were observed. As matrix, the authors used two previously developed [24][25][26][27][28] thermoset polymers based on epoxy-polyfunctional polysiloxanes cured with organic diamines. Two layered silicate fillers were used in this study: the natural montmorillonite MNa and the modified ''Bentonite for water systems'' (BW), which were to be further compatibilized by treatment with suitable organic compounds.…”

“…As compatibilizers, several polyalcohols, in some cases containing an amino group (for an easier incorporation in the epoxy matrix), such as polyethylene glycol 4000 (PEG), polysorbate 80 (TWEEN), and tris(hydroxymethyl) aminomethane (TRIS) were used, because they are expected to interact suitably with silicates and can be incorporated in the O-I matrix. They are readily soluble in water or water/alcohol mixture, which is used for the matrix synthesis, [26][27][28] and are commonly available, relatively cheap, nontoxic, and generally safe chemicals.…”