3.3 Application of antifouling performance of tri-Dopa-PSBMA
To verify the effectiveness of this polymer on the commonly used hydrophobic surface, we compared the wettability of the bare PVDF and DOPA-PSBMA modified PVDF membranes (Figure 4b ). The in-air water contact angle (WCA) of the bare PVDF membrane was 120°, while that of the PVDF-OH membrane decreased to 85°. The wettability of the DOPA-PSBMA modified PVDF membrane is indicated by a relatively low WCA (~ 20°), suggesting a successful attachment of DOPA-PSBMA on the PVDF surfaces. However, there is no significant difference between the in-air soybean oil contact angle (OCA) of the PVDF-OH and those of DOPA-PSBMA modified PVDF membranes with OCA of 25±5°. Although no superwettability has been reached on the DOPA-PSBMA modified PVDF membranes in the air64, the unique underwater superoleophobicity can be obtained due to the presence of the highly polar PSBMA chains, which endows the surface with the underwater self-cleaning property65. The soybean oil-stained bare PVDF-OH and DOPA-PSBMA-modified PVDF membranes were dipped into the water. Although partly dewetted, soybean oil droplets with high viscosity remained on the bare PVDF-OH and sin-DOPA-PSBMA modified PVDF membranes after 4 s of immersion. On the contrary, oil can be automatically detached from the tri-DOPA-PSBMA modified PVDF surface in 4 s (Figure 4c and Video 2 ). The excellent performance of tri-DOPA-PSBMA with different degrees of polymerization in water also shows its wide applicability. Consequently, the convenient modification technology with excellent self-cleaning properties will have great potential in industrial practice66.