Antifouling character of 'active' hybrid xerogel coatings with sequestered catalysts for the activation of hydrogen peroxide.

Halide-permeable xerogel films prepared from sols containing 50 mol% aminopropyltriethoxysilane (APTES)/50 mol% tetraethoxysilane (TEOS) or 10 mol% APTES/90 mol% TEOS and 0.015 M selenoxide or telluride catalyst in the sol gave reduced settlement of cypris larvae of the barnacle Balanus amphitrite and larvae of the tubeworm Hydroides elegans in the presence of artificial seawater (ASW) and hydrogen peroxide (5-100 microM) relative to glass controls. Settlement of Ulva zoospores was lower on both the 50 mol% APTES/50 mol% TEOS and 10 mol% APTES/90 mol% TEOS xerogel formulations in comparison with glass controls with or without the added catalyst.

Inhibition of barnacle (Amphibalanus amphitrite) cyprid settlement by means of localized, pulsed electric fields.

The increasing needs for environmental friendly antifouling coatings have led to investigation of new alternatives for replacing copper and TBT-based paints. In this study, results are presented from larval settlement assays of the barnacle Amphibalanus (= Balanus) amphitrite on planar, interdigitated electrodes (IDE), having 8 or 25 mum of inter-electrode spacing, upon the application of pulsed electric fields (PEF). Using pulses of 100 ms in duration, 200 Hz in frequency and 10 V in pulse amplitude, barnacle settlement below 5% was observed, while similar IDE surfaces without pulse application had an average of 40% settlement.

Hybrid xerogel films as novel coatings for antifouling and fouling release.

Hybrid sol-gel-derived xerogel films prepared from 45/55 (mol ratio) n-propyltrimethoxysilane (C3-TMOS)/tetramethylorthosilane (TMOS), 2/98 (mol ratio) bis[3-(trimethoxysilyl)propyl]-ethylenediamine (enTMOS)/tetraethylorthosilane (TEOS), 50/50 (mol ratio) n-octyltriethoxysilane (C8-TEOS)/TMOS, and 50/50 (mol ratio) 3,3,3-trifluoropropyltrimethoxysilane (TFP-TMOS)/TMOS were found to inhibit settlement of zoospores of the marine fouling alga Ulva (syn. Enteromorpha) relative to settlement on acid-washed glass and give greater release of settled zoospores relative to glass upon exposure to pressure from a water jet. The more hydrophobic 50/50 C8-TEOS/TMOS xerogel films had the lowest critical surface tension by comprehensive contact angle analysis and gave significantly greater release of 8-day Ulva sporeling biomass after exposure to turbulent flow generated by a flow channel than the other xerogel surfaces or glass.