Effects of PEG-TMS on the stability and antifouling performances of hydrocarbon-modified amphiphilic xerogel coatings

Amphiphilic xerogel films with slight swelling were prepared by the acid-catalysed sol-gel method starting from tetraethoxysilane (TEOS), triethoxyoctylsilane (C8Si), n -octadecyl trimethoxysilane (C18Si) and poly(ethylene glycol) siloxane (PEG-TMS). In these amphiphilic xerogel films, the presence of hydrophobic chains, especially C18Si facilitated the emigration of PEG chain to the coating/air interface during the film formation/curing process, and then the PEG chains enriched at the surface of coatings further slightly emigrated to form hydration layer underwater confirmed by energy dispersive X-ray spectroscopic (EDS) analysis, captive air-bubble contact angle (CA) and CA hysteresis. Furthermore, the amphiphilic xerogel films showed the optimal water absorption ratio lower than 1.0% due to the restraint of higher crosslinked density and little network aperture of the films on PEG chains. The antifouling performances of amphiphilic xerogel films included the protein resistance for FITC-BSA, antibacterial property for Escherichia coli and the resistance for diatom Navicula , were better than those of the elastic silicone-based coatings and xerogel film without hydrophilic PEG chains. In general, the amphiphilic xerogel films containing both PEG and proper levels of C8Si and C18Si possessed excellent fouling release properties and slight swelling due to the synergistic effects.