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.