Adhesion of façade coating colonisers, as mediated by physico-chemical properties

Abstract

The adhesion of Klebsormidium flaccidum, Stichococcus bacillaris and Chlorella cf. mirabilis, three strains of green microalgae isolated from biofilms on façade coatings were investigated in a parallel plate flow chamber. The model surfaces tested were glass slides, and −CH₃ (mediated by octadecyltrichlorosilane [OTS] and hexamethyldisilazane [HMDZ] modification) and -NH₂ (aminopropyltriethoxysilane [APS] modification) terminated self-assembled monolayers. Algal physicochemical properties were evaluated by the microbial adhesion to solvents (MATS) assay and by contact angle measurements. The model surfaces were characterised by X-ray photoelectron spectroscopy analysis and by contact angle measurements. Predicted adhesion trends were then compared to in vitro measurements. The adhesion strength of the three algal strains followed the trend: APS > OTS > HMDZ > glass. The adhesion process thus seemed to be mediated by hydrophobic and electrostatic interactions, and was shown to be influenced by the algal culture age and the initial contact time.

Keywords:

• Algae
• building
• adhesion
• self-assembled monolayers

Acknowledgements

The authors would like to thank Rhodia PPMC, Hexion Specialty Chemicals and the Association Nationale de la Recherche Technique (grant No. 294/2003) who funded this work. They are also indebted to Patrick Lasnet de Lanty (Rhodia) for his help in parallel plate flow chamber analysis and to Dr Mireille Turmine (Université Paris VI) for access to the tensiometer.