The impact of solvent content and curing conditions on drying and network properties of condensation curing PDMS films

Polydimethylsiloxane (PDMS) based fouling release coatings (FRCs) form a promising option to tackling the impact of marine biofouling on global shipping. Leaching of nonbonded additives in these films is anticipated to depend on network properties. Therefore, this work investigates the impact of solvent content and curing conditions on drying and final properties of condensation curing PDMS films. High-resolution 1D NMR imaging shows that solvent content only impacts drying during the first minutes after application. Here solvent evaporation and coating shrinkage are prevalent. Subsequently, the film's mobility and final state are found to be solely affected by curing conditions. NMR experiments and tensile tests show that longer crosslinking times result in lower final network mobilities, higher crosslink densities, higher elastic moduli and films that are able to withstand higher strains before rupturing. Consequently, this work shows that environmental conditions, prevalent during the application of silicone-based FRCs, will strongly affect their performance.