The number of hydrogen bonds n HB between water-water, water-polymer, and polymerpolymer is monitored and averaged across simulation trajectories for different surfaces. A hydrogen bond is considered as formed when two conditions are fulfilled: (i) the distance between donor and acceptor atoms does not exceed 3.5 Å and (ii) the angle formed by donor, hydrogen, and acceptor atoms exceeds 150 degrees. These calculations are facilitated by the Unit vectors defining molecular orientation n w and hydroxyl orientation n OH are monitored and spatially resolved as a function of distance d from the polymer-water interface. The orientation of the polymer-water interface can be locally specified as n p . These time-dependent quantities are used to calculate the relative orientation of water molecules and hydroxyl groups with respect to the water-polymer interface, respectively as α w = cos -1 ( n w • n p ) and