Figure 4. Quantitative evaluation of surficial hydrophobicity/hydrophilicity. (A) Process of surficial modification, top: the process of obtaining complex surface, bottom: the process of obtaining standard curve. Concentration of HBT-DPI in DCM solution: 1mM. (B) Complex surface modified by coving a mask, left: the mask, right: complex surface after stained by HBT-DPI . (C) The standard curve between fluorescent ratio and contact angle upon the PVDF membrane. (D) The comparison of hydrophobicity between various large-scale surfaces.