Irradiation of hydrophobic coating materials by gamma rays and protons: space applications

The responses of hydrophobic silicone-based coatings following irradiation by Co-60-gamma-rays are reported. The dimethylsilicone (DMS) resin coatings consisted of neat samples and samples incorporating semiconductor metal oxide (SMO) irradiated at photon energies of 1.17 and 1.33 MeV. Pre-and post-irradiation measurements indicated that at a total dose of similar to 185 krad(Si) there was no significant change to the coating static hydrophobic contact angles, surface molecular structure and biocide neutralization efficiency. The data was compared with previously irradiated and reported DMS/SMO coatings at a proton fluence of similar to 1.5 x 10(12) p/cm(2). Potential space applications for the radiation resistant coating self-cleaning properties are presented as well as a discussion of other environmental testing required to qualify the technology for transition to photonic space applications.