How Surface Wettability Affects the Binding, Folding, and Dynamics of Hydrophobic Polymers at Interfaces

We present an extensive molecular simulation study of the behavior of a flexible hydrophobic 25-mer polymer at interfaces presenting a range of chemistries from hydrophobic (−CH3) to hydrophilic (−CONH2). We quantify the free energy of adsorption, conformational equilibria, and translational and conformational dynamics of the polymer at these diverse interfaces. Water-mediated interactions drive the polymer to adsorb strongly at a hydrophobic interface and repel it from hydrophilic ones. At hydrophilic surfaces, van der Waals interactions between the polymer and the surface mitigate this water-mediated repulsion, leading to weak adsorption of the polymer. Although the polymer is strongly adsorbed to hydrophobic surfaces, it is also most dynamic there. Translational diffusion and conformational dynamics are faster at hydrophobic surfaces compared to those at hydrophilic ones. In bulk water, the polymer collapses into compact globular shapes, whereas the thermodynamic stability of folded polymers is signifi...