In this article, thick (~15 pm) silicon-oxo-dominated nanocomposite coatings with high transparency were fabricated by incorporating 3-methacryloxypropyltrimethoxysilane (MPS)-modified silica alcosol into a moisture-curable polysiloxane oligomer and curing with the aid of 3-aminopropyllriehtoxysilane (APS).
Silica alcosol (30% solid content, particle size = 20 nm) was purchased from Zhangjiagang Churen New Materials Co., Ltd.
Silica alcosol was added to a 50-mL round-bottom flask and magnetically stirred, and MPS was added drop-wise to the stirring vessel.
The MPS-modified silica alcosol was mixed with the as-obtained polysiloxane oligomer solution and sonicated for approximately 3 min.
Preliminary experiments showed that direct addition of silica alcosol to the as-obtained polysiloxane oligomer solution resulted in an opaque mixture.
The colloidal silica nanoparticles were centrifuged from the MPS-modified silica alcosol for FTIR characterization, as shown in Fig.
This mechanical behavior is analogous to behaviors exhibited in colloidal-silica-embedded organic coatings."' Thus, the incorporation of unmodified silica alcosol is not an efficient route to produce hard and tough coatings.
Figure 3 displays the load-hold-unload curves of silicon-oxo-dominated coatings prepared with MPS-modified silica alcosol. Samples fabricated with unmodified silica alcosol are shown for comparison.
A monotonous increase of the micromechanical properties is revealed only for coatings with S28 silica alcosol. Compared with the R0 coating, decreased rigidity is observed for all nanocomposite coatings with 5 wt% silica content.