With increased PS loading, van der Waals and hydrophobic interactions occur between the methyl-containing (e.g., alkylamide, methylester) residues of PS and the diamond. We therefore suggest hydrophobic pockets form directly adjacent to the diamond surface as more PS is adsorbed (Figure ). The high relative contribution of carboxylate-containing groups at the highest PS loading leads to the formation of electrostatic interactions between NH2 + and COO - groups. As will be discussed in the next section, this sequence of events increases the hydrophilicity of the PS-diamond surface during the early stage of PS adsorption on the diamond surface.