Antifouling Potential of Lubricious, Micro-engineered, PDMS Elastomers against Zoospores of the Green Fouling Alga Ulva (Enteromorpha)

Abstract

The settlement and release of Ulva spores from chemically modified, micro-engineered surface topographies have been investigated using poly(dimethyl siloxane) elastomers (PDMSe) with varying additions of non-network forming poly(dimethyl siloxane) based oils. The topographic features were based on 5 μm wide pillars or ridges separated by 5, 10, or 20 μm wide channels. Pattern depths were 5 or 1.5 μm. Swimming spores showed no marked difference in settlement on smooth surfaces covered with excess PDMS oils. However, incorporation of oils significantly reduced settlement density on many of the surfaces with topographic features, in particular, the 5 μm wide and deep channels. Previous results, confirmed here, demonstrate preferences by the spores to settle in channels and against pillars with spatial dimensions of 5 μm, 10 μm and 20 μm. The combination of lubricity and pillars significantly reduced the number of attached spores compared to the control, smooth, unmodified PDMSe surfaces when exposed to turbulent flow in a flow channel. The results are discussed in relation to the energy needs for spores to adhere to various surface features and the concepts of ultrahydrophobic surfaces. A factorial, multi-level experimental design was analyzed and a 2nd order polynomial model was regressed for statistically significant effects and interactions to determine the magnitude and direction of influence on the spore density measurements between factor levels.

Keywords:

• adhesion
• biofouling
• Ulva (Enteromorpha)
• topography
• settlement
• surface energy
• PDMS

Acknowledgements

We gratefully acknowledge the financial support of the Office of Naval Research, awards #N00014-96-0373, #N00014-99-0311 and #N00014-02-1-0521 to JAC & MEC and #N00014-03-1-0919 to ABB.