Amphiphilic molecules are frequently used as additives in many polyolefin blends. These amphiphiles have been observed to self-organise and migrate to the surface of polymers during processing and after extrusion, affecting the performance and shelf life of the product. These amphiphiles perform two key functions: imparting enhanced wettability of the polymer and improving the processing of the blend by modulating the wall-slip that occurs during extrusion. Using a combination of neutron reflectivity and ion beam analysis, we have shown that there is an enriched layer of amphiphile present at the surface and the thickness of this layer has been quantified. We have also shown that this surface layer is sufficiently mobile to evolve over time. After exposure to water, a hydrophilic-hydrophobic switch occurs without loss of amphiphile from the film. This is evidence that a structural rearrangement of the surfactant occurs and that there is little loss of additive on exposure to water. Temperature elevation has also been investigated and a decrease in the thickness of the enriched layer was observed. This temperature effect has implications for the optimum storage conditions of finished products as this change in additive distribution may impair the desired function of the product.