[shown as red rectangles in Fig. ] is the region that starts from this z value (that corresponds to the average brush height) and extends to z + 10Å. Finally, the rest of the nanochannel that is outside these two regions is the "bulk region" [shown as blue rectangles in Fig. ]. Of course, the average brush height represents the average length of the brush along the z direction or perpendicular to the nanochannel wall (please see section S3.2 in the SI for calculation details).