Extent of coverage of surfaces treated with hydrophobizing microemulsions: A mass spectrometry and contact angle study

Glass surfaces were treated with various hydrophobizing microemulsions (HME) containing mineral seal oil or polyisobutylene as hydrophobes emulsified by dimethyl dicoco ammonium chloride (i.e. mimicking commercial car wash practices) and characterized by mass spectrometry (MS) and contact angle measurements. The cationic emulsifier mediates the anchoring of hydrophobes to the polar glass surface. It is demonstrated that by the use of even very low (0.3-3.0 w%) HME concentrations the surfaces become hydrophobic and repel water even after numerous (∼20) rinsing cycles. According to MS evidence, however, the surfaces are not fully saturated with hydrophobes and the unprotected areas remain vulnerable to environmental damage.