CONTROL OF SOLAR INSOLATION VIA THERMOCHROMIC LIGHT-SWITCHING GELS

The investigated thermochromic gels show a phase separation when a cha racteristic temperature is surpassed. Particles are formed within a po lymer network, which are responsible for a drastically increased light scattering efficiency. Accordingly, a reduction in the directional-he mispherical transmission in the solar spectral range from 81 +/- 2 to (10 +/- 1(5))% for a 1 mm thick foil-gel-foil system was observed. Wit h the help of differential light scattering measurements and Debye's t wo-phase media model correlation lengths of a(c) = (100 +/- 20) nm and a(c) = (400 +/- 50) nm were derived for the scattering entities in th e clouded case. From the optical thickness of the specimens the switch ing temperatures are derived. Additionally performed multiflux calcula tions for a purely scattering switching system allow to predict the ra diation transport under variation of the optical thickness and the cor relation length.