Heptadecafluorodecyl Trimethoxysilane

Heptadecafluorodecyl-trimethoxysilane (CAS 83048-65-1) is a fluoroalkylsilane glass-coating active used in CarPro FlyBy30 and historically in some Aquapel and professional-grade windshield treatments. The chemistry combines a perfluorinated C8 alkyl chain (the "heptadecafluorodecyl" portion — 17 fluorines on a 10-carbon chain) with a trimethoxysilyl anchor group that bonds to silica-rich substrates like glass.

The performance benefit is genuine: fluorine substitution produces very low surface energy, which translates to high water contact angles (tight beading), high oil contact angles (oleophobic resistance to bug splatter and road grime), and chemical durability against most polar liquids. The cured film is one of the more durable consumer-applicable glass coatings.

The environmental cost is the reason the chemistry has been increasingly restricted in industrial applications. The C8 perfluoroalkyl chain meets the OECD PFAS structural definition (any substance containing one or more perfluoroalkyl moieties); the C–F bonds resist normal environmental degradation pathways, leading to indefinite persistence in soil and water. The chain length (C8) places this compound in the same persistence and bioaccumulation tier as PFOA — though the silane anchor and the H,H,H,H spacer differentiate it from PFOA itself, the overall environmental profile is similar.

Use in finished glass coatings is at 1-5% concentration. Per-application volume is small (a few mL per windshield once a year), but the cured film does eventually weather off the glass surface and enters drains and waterways through normal car washing.