Even though the S and M polymers were chosen to minimize a natural interphase, our data suggest that a small region of molecular mixing still occurs even between those polymer layers. This interphase region is increasingly accessible with probes of decreasing radius. For the following analysis to account for the substrate effect, we chose to use A = 0.64 and b = 1.48 from the universal master curve, since it is impractical to determine these parameters for each real system of interest. Further discussion about this choice of fitting parameters is provided in section 3.5.