Perfluoroalkyl substances (PFASs) are fully fluorinated, stabile, and surface-active compounds. They contain both a hydrophobic fluorinated carbon chain and an ionizable hydrophilic functional group, and can interact with biological membranes through different pathways, such as adsorption, penetration and displacement. PFASs have been found to accumulate in organisms in the environment, but there is a lack of knowledge on the mechanisms behind the accumulation. This proposal aims to use neutron reflection to investigate the interactions of perfluorooctane sulfonate, perfluorononanoate and perfluorohexanoate with standard eukaryotic mimic biomembrane and compare with model plant membrane to elucidate the influence of different functional groups and chain lengths on the sorption/accumulation behavior at the two different types of membranes.