Effect of Variations in Micropatterns and Surface Modulus on Marine Fouling of Engineering Polymers

Abstract

We report on the marine fouling and fouling release effects caused by variations of surface mechanical properties and microtopography of engineering polymers. Polymeric materials were covered with hierarchical micromolded topographical patterns inspired by the shell of the marine decapod crab Myomenippe hardwickii. These micropatterned surfaces were deployed in field static immersion tests. PDMS, polyurethane, and PMMA surfaces with higher elastic modulus and hardness were found to accumulate more fouling and exhibited poor fouling release properties. The results indicate interplay between surface mechanical properties and microtopography on antifouling performance.

Keywords: PDMS; biofouling; poly(methyl methacrylate); polyurethane; surface patterning; surface properties.

Figure 1

Schematic representation of the surface engineering process described in the text.

Figure 2

Hierarchical surface patterns, inspired by the carapace surfaces of marine decapod crab Myomenippe hardwickii, consisting of two overlapping hexagonal arrays of 100 μm cylinders and 3 μm (a, b) and 5 μm diameter pillars (c), respectively, reproduced in PU using compression molding. The scale bars correspond to 100 (a), 50 (b), and 50 μm (c), respectively.

Figure 3

Hardness (left) and elastic modulus (right; means ± SD) of the smooth and patterned polymer substrates discussed in this study. We marked significant differences between samples (‘***’ p < 0.001).

Figure 4

Results of the static field immersion test −1st immersion. Figure shows mean values (± SE) of total counts of organisms settled on smooth and patterned (5 μm + 100 μm, and 3 μm + 100 μm hierarchical structures) test samples after the first 2 weeks of immersion before (0 psi) and after cleaning with water jet (50 and 100 psi, respectively). We note that, due to technical difficulties in pattern replication in PMMA, PMMA samples with 5 μm pillars were tested as a single replicate only. PVC was used as an internal reference material.

Figure 5

Results of the static field immersion test −1st immersion. Table shows images of smooth and patterned (5 μm + 100 μm, and 3 μm + 100 μm hierarchical structures) test samples after the first 2 weeks of immersion before (0 psi) and after cleaning with water jet (50 and 100 psi, respectively).

Figure 6

Results of the static field immersion test −2nd immersion. Figure shows means (± SE) of total count of organisms settled on smooth and patterned (5 μm + 100 μm, and 3 μm + 100 μm hierarchical structures) test samples after 2 weeks of the second immersion before (0 psi) and after cleaning with water jet (50 and 100 psi, respectively).

Figure 7

Results of the static field immersion test −2nd immersion. Table shows images of smooth and patterned (5 μm + 100 μm, and 3 μm + 100 μm hierarchical structures) test samples after 2 weeks of the second immersion before (0 psi) and after cleaning with water jet (50 and 100 psi, respectively).