Neutron reflection has been successfully used to measure the conformation of proteins adsorbed at the oil/water interface. However, in several such experiments, hexadecane has been used as an oil substrate for cost and practicality reasons. Polydimethylsiloxane (PDMS) is widely used for medical applications in which protein adsorption is a key factor, such as drug storage and delivery. This experiment will examine whether hexadecane is a useful model substrate for PDMS, and thus whether it is suitable for future practical protein adsorption investigations. The adsorption of two proteins, bovine serum albumin, and the monoclonal antibody COE-3, will be investigated to determine if their behaviour is similar at both interfaces, and thus whether the hexadecane/water interface is a useful analogue for the PDMS/water interface.