Atomic force microscopy of nanofiltration membranes: Effect of imaging mode and environment

► Detailed study on nanofiltration membrane of different degree of hydrophobicity in liquid using AFM tapping and contact modes. ► AFM studies were complimented by the membrane transport method and contact angle measurements. ► A number of features were observed when imaging PES 20% PVP 20% membrane with AFM tapping mode in water. ► The image is backed up by the relatively hydrophobic nature of the membrane, the shape being similar to nanobubbles previously described in the literature.