Effect of proton irradiation on the optical properties of thermal control coating based on polystyrene with silica filler

This paper presents the results of studying the surface properties changes of a thermoregulating coating based on polystyrene and silica filler after proton irradiation with an energy of 50 keV at a fluence of 3 × 10¹⁵ cm⁻². After proton irradiation, the values of the contact angle of wetting with water increase by 3.5% and 14.9% for polystyrene and the coating, respectively. The free surface energy (energy of the surface layer) of polystyrene and the coatings before and after proton irradiation was calculated using the Owens-Wendt-Rabel-Kaelble method. There was a significant increase in the polarity of the polystyrene surface (γ_p increased by a factor of 2.2) after proton irradiation. For the coating, an increase in γ_p by a factor of 3.89 was observed after proton irradiation. Structural changes in the coating were presented by IR Fourier spectroscopy. A slight decrease in the absorption intensity of all characteristic bands compared to the unirradiated sample was noted. It was found that the irradiation of the coating with protons led to the formation of macromolecules with hydroxyl, carbonyl, and carboxyl bonds, as well as the formation of dimeric and oligomeric siloxane chains. It was also found that after irradiation of a pure polystyrene sample with protons, the value of the solar absorption α_s increased by only 4.2%; whereas for the coating with silica filler, the value of α_s increased by 28.6%.