As previously noted, the capacity for hydrogen bonding likely explains the lesser hydrophobicity of PMMA, N66, and PVA compared to PTFE, PE, and PVC. Within the group of hydrogen-bonding polymers, the extent and nature of hydrogen bonding determines their relative hydrophobic ordering. Fig. presents a breakdown of the number and type of hydrogen bonds formed near water-polymer interfaces. The overall number of hydrogen bonds formed between polymer and water increases in the order of N66 * < PMMA < N66 < PVA † < PVA, which perfectly aligns with decreasing order of hydrophobicity prescribed by the metrics for nanoscale hydrophobicity (e.g., β∆f σ ). This analysis also makes clear why N66 * is more hydrophobic than PMMA while N66 is more hydrophilic: crystallinity in N66 inhibits the formation of hydrogen bonds, which is not necessarily evident by simple consideration of the polymer chemistry. The nature of hydrogen bonding also impacts water orientation as shown in Fig. . Because PMMA can only function as an acceptor for hydrogen bonding with its oxygen atom, the α OH distribution is diffusely peaked around 30 • , orienting a single hydrogen towards the polymer-water interface. By contrast, both N66, PVA, and PVA † can all accept and donate in hydrogen-bonding networks, which manifests in an overall flatter α OH distribution and more facile hydrogen bonding. The difference in hydrophobicity between PVA and PVA † surfaces might be further understood by considering how hydrogen bonds are distributed within each polymer near the polymer-water interface (Fig. ). Here, PVA † , which is isotactic, demonstrates greater propensity to form hydrogen bonds with adjacent monomers on the polymer chain, while hydrogen bonding in PVA is more varied. We posit that the more static nature of intra-polymer hydrogen bonding in PVA † leads to fewer and weaker hydrogen bonds with water and thus a modest enhancement in hydrophobic character.