The objective of this experiment is to use neutron reflectivity to study the surface structure and determine chemical depth profiles of Perflouropolyether-PDMS films in air and in water. We wish to understand the surface structures formed by these films in different environments. Particularly we wish to better understand the surface segregation of the Perflouropolyether component in water. We will also look at the effect of cross link density on surface reconstruction between air and water. We intend to relate the surfaces presented by these films to their antifouling properties and performance.In this resubmission we have made clearer the need to use neutron reflectivity to study and dynamic contact angle measurements demonstrating evidence of surface reconstruction and speed of surface changes.