Mussel-inspired design of a catechol-polydimethyl siloxane covalent hybrid polymer for atomic oxygen resistant coating application

Design of materials embodying the adhesive and cohesive nature of mussel byssal protein mimics have long served to inspire material developers in uncommon areas. Herein, a Catechol-Polydimethyl Siloxane Covalent Hybrid polymer (PGDX) derived from mussel chemistry is demonstrated as a highly effective atomic oxygen resistance (AOR) coating/adhesive, a yet unreported activity. The rational design of PGDX through a greener route is derived from poly dimethyl siloxane diglycidyl ether (PG) and dopamine (D). PGDX coating achieved excellent AOR on commonly used aluminised polyimide (AI-PI) and polyimide (PI) multilayer insulation materials for satellites as exposure to AO fluence of 2.5 × 1020 atom/cm2 resulted in 47 % and 71 % reduction in mass-loss rate for AI-PI and PI respectively. The hybrid morphology of the polymer enabled its solubility in solvents having different polarities thus widening the scope of coating perspectives of dopamine. The coated substrates possessed lower surface energy (PI/Al-PI, 23.6/24.8 mN/m) than their uncoated counterparts (Al-PI/PI, 29.60/34.4 mN/m) and lower work of adhesion that denoted the hydrophobicity of the coating owing to the siloxane segment. The modified PDMS backbone with mussel chemistry show potential for application as a coating and adhesive for protecting delicate satellite components from the highly degrading AO rich Low Earth Orbit (LEO) environment.