Highly corrosion resistant siloxane-polymethyl methacrylate hybrid coatings

Organic-Inorganic Hybrid Coatings for Corrosion Protection of Metallic Surfaces

“…Table 2 shows the temperature of the limit of thermal stability, T 0 , for all epoxysilica hybrids, defined as the temperature of 5% weight loss during the annealing process. The hybrids presented a thermal stability of about 300°C, relatively high values compared with those of other polymeric and hybrid materials [18,22]. This advantageous property comes from the highly cross-linked structure provided by the curing agent (DETA) combined with the high polycondensation degree of the silica phase, as revealed by 29 Si NMR.…”

“…Varying the MMA/MPTS molar ratio from 2 to 10, NMR and SAXS results have shown that the M8 sample (MMA/MPTS = 8) presented the highest degree of polycondensation (83.9%) of the silica nanoparticles with an average radius of 0.8 nm, spaced by PMMA segments over an average distance of 4.6 nm. This coating exhibited also an excellent adhesion to the substrate (detachment force > 3.5 MPa) and the best anti-corrosion performance [10,22]. EIS and potentiodynamic polarization results have shown that the M8 coating deposited on carbon steel acts as a very efficient corrosion barrier, increasing the total corrosion resistance by almost 6 orders of magnitude (>1 GΩ cm 2 ) and reducing the current densities by more than 4 orders of magnitude (<0.1 nA cm −2 ), compared to the bare steel substrate [22].…”

“…This coating exhibited also an excellent adhesion to the substrate (detachment force > 3.5 MPa) and the best anti-corrosion performance [10,22]. EIS and potentiodynamic polarization results have shown that the M8 coating deposited on carbon steel acts as a very efficient corrosion barrier, increasing the total corrosion resistance by almost 6 orders of magnitude (>1 GΩ cm 2 ) and reducing the current densities by more than 4 orders of magnitude (<0.1 nA cm −2 ), compared to the bare steel substrate [22]. Furthermore, XPS analysis confirmed that no corrosioninduced changes had occurred after 18 days of immersion in 3.5% NaCl solution [22].…”

“…Structural analysis of PMMAsilica hybrids, performed by AFM, SAXS, NMR and XPS, has shown that the nanostructure is formed by a dense amorphous network of ramified silica-siloxane cross-link nodes, covalently interconnected by short PMMA chain segments [10,22]. Varying the MMA/MPTS molar ratio from 2 to 10, NMR and SAXS results have shown that the M8 sample (MMA/MPTS = 8) presented the highest degree of polycondensation (83.9%) of the silica nanoparticles with an average radius of 0.8 nm, spaced by PMMA segments over an average distance of 4.6 nm.…”

“…Increasing the synthesis temperature from 70 to 80°C and the time of reaction from 2 to 4 h (sample M8_4h), an increase in the amount of polymeric phase was detected yielding a more compact and durable coating (56 days) [18,22]. After optimizing also the ethanol-to-water ratio of the inorganic phase to a value of 0.2, the corrosion resistance and lifetime were further increase to 196 days in 3.5% NaCl (M8_4h_E0.2 coating, Table 4) [10].…”