Rheological and optical properties of solar absorbing paints with POSS-treated pigments

Thickness sensitive spectrally selective (TSSS) coatings should be capable of absorbing high amounts of solar energy, i.e. they should exhibit high solar absorptivity. However, due to their sensitivity to thickness, it is extremely difficult to prepare uniform, smooth and thin coatings with dense distribution. In our study, we prepared black TSSS paints at various PVC ratios by using a pigment that was treated with trisilanol POSS dispersants. Various POSS dispersants were used for pigment treatment in order to determine the influence of POSS structure on the rheological behavior of liquid paints and the solar absorptivity of applied coatings. Liquid paints were prepared at various PVC ratios in order to examine the effect of pigment loading on the rheological behavior of the paint. The rheological properties were correlated to the solar absorptivity of coatings applied on the substrate. The results revealed that POSS dispersants enable the preparation of dispersions with particularly high pigment loadings (above PVC = 51), which still exhibit liquid-like viscoelastic behavior and are sufficiently flowable to enable proper leveling, uniform distribution of pigment particles inside dry coating and, therefore, excellent solar absorptivity.