Polydimethylsiloxane/silica hybrid coatings protecting Kapton from atomic oxygen attack

In order to improve the erosion resistance of spacecraft materials in atomic oxygen (AO) environments, a kind of polydimethylsiloxane (PDMS)/SiO2 hybrid coatings has been prepared on Kapton by a sol–gel process. The tetraethoxysilane (TEOS) and silanol-terminated PDMS were used as two main precursors. The content of inorganic silica in the PDMS/SiO2 hybrid coatings varied, achieving a maximum value of 40 wt% under the addition of a coupling agent. The PDMS/SiO2 hybrid coatings possessed good adhesion and flexibility, improved thermal stability. The AO resistance of the hybrid coatings was investigated by exposure tests in the AO simulator. The results showed that the hybrid coatings had excellent AO resistance. The PDMS/SiO2 (20 wt%) hybrid coating had an erosion rate two orders of magnitude slower than the polyimide film, and did not crack during AO exposure. The coating performance was also found to improve with increasing SiO2 content.