Reducing attachment of marine diatoms and bacteria by fine tuning the modulus of PDMS based coatings

Abstract

In recent years there has been an increase in the use of non-toxic fouling-release coatings to combat marine biofouling on the hulls of ships and a number of commercial products are established on the market. While fracture mechanics is considered to play a key role in the removal of macrofouling organisms, the effect of coating modulus on microfoulers is still poorly understood. A method to produce PDMS coatings with different moduli using a tin free condensation curing system has been established in our laboratory. The coatings were used to study the attachment of marine biofilm-forming organisms. Curing chemistry was investigated by solution and solid state ²⁹Si-NMR spectroscopy and the mechanical properties characterized by pendulum hardness tests. The coatings were tested against the attachment of three marine organisms Ulva linza, Navicula perminuta and Cobetia marina. The choice between dynamic and static assay conditions was found to be very important for soft fouling organisms. Under dynamic conditions, harder modulus coatings reduced the attachment of marine bacteria and diatoms.