Microstructural Surface Properties of Drifting Seeds-A Model for Non-Toxic Antifouling Solutions

Abstract

A major challenge in the shipping and marine industry is the biofouling on under water surfaces. So far, biocides have been the main remedy for the prevention of the adhesion of microorganisms that is also influenced by surface topography. In recent years, research projects have explored microstructured surfaces as a non-toxic antifouling strategy. In this study, physical factors of surfaces of seeds of 43 plant species were analyzed with regards to their antifouling effects. After exposure to cold water of the North Sea during the swarming periods of the barnacles larvae, the surface microstructures of seeds without fouling of barnacles were identified and compared with each other, using a scanning electron microscope (SEM). In order to validate the findings, selected microstructured surface structure properties were transferred to technical surfaces with a 2-component silicon system and subjected to the same conditions. The results of the analyses confirmed that drifting seeds with specific microstructural surface structure properties promote biofouling defense of epibionts. These results serve as a starting point for the development of non-toxic antifouling agents based on the interaction of microstructures and geometric shapes.

Keywords: SEM; biofouling; biofouling analysis; biomimetic; drifting seeds; surface structure; technical surface.

Figure 1

Samples and Scanning Electron Microscopy (SEM) images of seeds with antifouling properties (A) Acoelorrhaphe wrightii, (B) Coccothrinax borhidiana, (C) Erythrina berteroana, (D) Ipomoea alba, (E) Licuala spinosa and (F) Sapindus saponaria.

Figure 1

Samples and Scanning Electron Microscopy (SEM) images of seeds with antifouling properties (A) Acoelorrhaphe wrightii, (B) Coccothrinax borhidiana, (C) Erythrina berteroana, (D) Ipomoea alba, (E) Licuala spinosa and (F) Sapindus saponaria.

Figure 2

Mean roughness (Ra) of the profiles of six drifting seed species and their standard deviations (n = 5) in comparison to the reference glass ball determined by means of the digital elevation models. (Standard deviation of E. berteroana, I. alba and S. saponaria are not visible; <9% of the mean).

Figure 3

SEM images of test surfaces with integrated particles. From left to right: (a) surface of the silicone mixture without particles, (b) surface of the silicone mixture integrated with Poraver particles and (c) surface of the silicone mixture integrated with Q-Cel particles.

Figure 4

Adhesion of barnacles to surfaces after 12 weeks of exposure to the North Sea (after cleaning). (a) V2A-steel reference, (b) silicone mixture with Poraver particles and (c) silicone mixture with Q-Cel.

Figure 5

Mean values and standard deviations of the percentage biofouling (n = 3) of the test surfaces removed compared to the reference V2A-steel before and after water jet cleaning.