Other trends that can be directly observed from the data in Figure is that particle size decreases when the flow rate is overall increased. This can be attributed to the limited time available for nanoparticle formation at higher flow rates. While this is a trend that is often observed in our experiments, the situation is markedly more complex when data is overlayed as in Figure (c) for various total flow rates and increasing mixing ratios and in 3(d) for various mixing ratios and increasing total flow rates. Only in a 3D plot as given in Figure (e) a comprehensible picture is obtained. To discuss these 3D plots, it is useful to display them with according surface plot fits. This is given in Figure for a variety of polymers and respective polymer concentrations (more plots for the remaining polymer concentrations can be found in the supporting information).