The research topic is Low surface energy materials (LSEMs), and development of new hydrocarbon architectures as replacements for environmentally hazardous fluorocarbon surfactants and polymers. The aim is to explore how surfactant chain length and branching affects adsorption at the air-water interface (surface excess and hence surface tension/energy). The surfactants of interest are shown in Figure 1: the subtle structural modifications in the tails, feed through to significant effects on surface tension of complete monolayers. Analyses of tensiometric data (Table 1) indicate that higher branching factor and closeness of the branch to the head group promotes an effective surface tension reduction and also a decrease in the effective molecular area. The proposal is to employ contrast variation neutron reflectivity (NR) to determine adsorption isotherms and layer structures.