Fig. 3.

Surface morphological and chemical characterizations of generated samples. (a) SEM images at different positions along the gradient samples. High-magnification SEM images of samples (b) prior to and (c) post chemical etching. (d) Cross-sectional SEM image and (g) EDS line scan of element profile. (e) ATR-FTIR spectra of Mg samples before and after MgF₂-PDA coating. (f) Static contact angle measurements at different positions along gradients. (h) Schematic illustration of surface alterations after each step of modification.