Threshold hydrophobicity for inhibition of salt scale formation on SAM-modified titania nanotube arrays

•Examined alkyl chain length effect on wetting of phosphonate SAM-coated TiO2 nanotubes.•Hill-Langmuir equation nicely fits contact angle vs carbon chain length variation.•Superhydrophobic functionalized TiO2 nanotube arrays inhibit scale formation.•Scale-resistant surfaces survive five cycles of deposition-precipitation of salts.•Threshold hydrophobicity required to impede dissolved ion-surface interactions.