Multifunctional nanolayers, self-healing and slow release coatings against biocorrosion and biofouling - A review

In order to extend the service life of metallic structures special protection systems are developed. The usefulness of multifunctional molecular layers that can control not only the chemical/electrochemical corrosion but the microbiologically influenced material deterioration too, will be discussed focusing on the surface characteristics of nanocoatings. Several examples will enlighten the impact of the nanofilms on the microbial life (metabolisms, multiplication, microbial adhesion, biofilm formation). From the point of view of the microbiologically influenced corrosion (MIC) the inhibition of biofilm formation (that starts with the microbial adhesion) is a crucial factor. The other group of coatings (that is much thicker than nanofilms) can prevent the material degradation with different mechanisms. In one case the chemicals with antimicrobial activity are enclosed into small particles surrounded by shell walls, and the spheres are dispersed in paints. When the active antimicrobial material (together with other additives) will get free on mechanical or chemical impacts, the damaged paint will be recovered and the coating keeps its original inhibitive characteristics. The other class of the special paints is the so-called slow-release coatings when the active antimicrobial material is released continuously. Advantages and disadvantages of these surface modifications will be compared.