Optical assessment of a fouling-resistant surface (PHEMA/ benzalkonium chloride) after exposure to a marine environment

A hydrogel based on poly(2-hydroxyethyl methacrylate) (PHEMA) containing benzalkonium chloride (BAK) can be used as an environmentally acceptable, fouling-resistant material in the marine environment. The loaded hydrogel system is transparent and has the potential to be used in the protection of optical ports in underwater instruments. Ultraviolet–visible (UV–vis) spectroscopy was used to study the optical properties of the material after a marine exposure period. The optical transmittance of PHEMA/ BAK was higher for 10 weeks than that detected for poly(methyl methacrylate) (PMMA), a material currently used in commercial instruments, which confirmed the superior fouling resistance of the PHEMA/ BAK combination. The UV–vis spectroscopic method was quick, relatively cheap and accurate enough to allow the effects of the development of marine fouling on transparent surfaces for use in marine underwater optical applications to be monitored.