We wish to develop a rational understanding of the mechanisms underlying the way water soluble polymer brushes - in particular those of polyethylene oxide/polyethylene glycol - can resist protein adsorption and thus confer biocompatibility on surfaces. To do this, we need to study systematically the kinetics of protein adsorption on well-characterised PEO brushes as a function of brush molecular weight and grafting density. Our preliminary experiments have shown that we are in a position to prepare polymer brushes with good control over these parameters; now we need to complement laboratory based experiments using quartz-crystal microbalance and ellipsometry with neutron reflection experiments that will yield both the details of the brush segment length density profile and the precise nature of the interaction between the adsorbing protein molecule and the polymer brush.