Overview of Silica-Polymer Nanostructures for Waterborne High-Performance Coatings

Combining organic and inorganic components at a nanoscale is an effective way to obtain high performance coating materials with excellent chemical and physical properties. This review focuses on recent approaches to prepare hybrid nanostructured waterborne coating materials combining the mechanical properties and versatility of silica as the inorganic filler, with the flexural properties and ease of processing of the polymer matrix. We cover silica-polymer coupling agents used to link the organic and inorganic components, the formation of hybrid films from these silica-polymer nanostructures, and their different applications. These hybrid nanostructures can be used to prepare high performance functional coatings with different properties from optical transparency, to resistance to temperature, hydrophobicity, anti-corrosion, resistance to scratch, and antimicrobial activity.

Preparation of hydrophobic epoxy-polydimethylsiloxane-graphene oxide nanocomposite coatings for antifouling application

Epoxy-polydimethylsiloxane-graphene oxide (EPG) nanocomposite coatings were successfully developed by loading different wt% of graphene oxide nanosheets (GNs) into an epoxy-hydroxy-terminated-polydimethylsiloxane (EP-hPD) matrix via a facile in situ preparation technique. The inclusion of GNs into EPN led to an increase in modulus of elasticity and tensile strength up to 1570.46 MPa and 31.54 MPa, respectively, in the case of 1 wt% loading of GNs in the EP-hPD matrix. Also, an increase in the water contact angle from 90.1° to 115.2°, 104.5° and 101.7° was discerned at 1, 3 and 5 wt% loadings of GNs respectively. Taber abrasion results demonstrated a decrease in abrasion loss by 33.3% at 1 wt% loading of GNs in comparison to the unreinforced coating. An improvement in the glass transition temperature (T_g) was observed from 63.5 °C for the neat sample to 77.6 °C, 76.3 °C and 71.6 °C for the 1, 3 and 5 wt% EPG nanocomposites, respectively. An inevitable enhancement in the properties of the nanocomposites was affirmed due to the synergistic effect of GNs dispersed within the EP-hPD blend matrix. The prominent findings of this work include a minimum corrosion rate of 0.73 × 10^-2 mm per year and upgradation in the antifouling performance of the nanocomposite coatings in comparison to the neat coating.