clarified by FESEM and XPS. Fig. 4c and d shows the morphology of
etched and healing fabrics. Under SEM, both the etched superhydrophobic
fabric and self-healing fabric show the hierarchical
structures as before. However, their surface chemical distribution
investigated by XPS changed obviously. As shown in Fig. 2b and
Table S1, after O2 plasma treatment, the C/O/F mass ratio was
66.38:26.2:7.42, the C/O ratio of etched fabrics was much lower
than that of the superhydrophobic fabrics. The result can be
explained that O2 plasma treatment can etch away the attached
PFW/GF and produce oxygen containing hydrophilic groups on the
coating surface. The raised surface energy combined with highly
rough structure inherent explains the superhydrophilicity of etched
fabrics. While after being annealed at 110 C for 3 min, the C/O mass
ratio (86.71:5.91) of the healing fabric increased significantly
(Fig. 2b and Table S1). This result indicates that heat treatment
leads to PFW/GF attached on fibers or loaded in gaps restore the
etched surface. Therefore, the damaged fabric regains its superhydrophobicity
due to the regenerated fresh surface on the fibers.
3.3. Mechanical stability of the superhydrophobic fabrics
We then conducted the mechanical stability of the superhydrophobic
fabrics via an abrasion test and a stretch test. The
methodology of the abrasion test is illustrated in Fig. 5a; the
superhydrophobic fabric was subjected to a 4.1 kPa and kept close
contact with the sandpaper (1000 mesh served as an abrasion
surface). Then the fabric sample was dragged in one direction with
a speed of 3 cm/s and abrasion length of 15 cm, respectively. As
shown in Fig. 5b, the CA changed slightly, while SA increased
gradually with increasing the abrasion cycles. This result showed
that SA is more sensitive than CA in evaluating wetting behavior of
the samples after abrasion tests. This is because slight damage to
the coating may result in evident increase in adhesion force between
the coating and water droplets, and then the increased SA
can be detected. Fig. 5c showed that partial PFW/GF layer was
removed after 600 scratch cycles, which result in a relative smooth
surface, whereas the rough structure still remained. Thus, the fabric
remains its superhydrophobicity and water droplets still could roll
off the high tilted samples even after 600 scratch cycles. The
enhanced mechanical resistance results from strong attachment of
clarified by FESEM and XPS. Fig. 4c and d shows the morphology ofetched and healing fabrics. Under SEM, both the etched superhydrophobicfabric and self-healing fabric show the hierarchicalstructures as before. However, their surface chemical distributioninvestigated by XPS changed obviously. As shown in Fig. 2b andTable S1, after O2 plasma treatment, the C/O/F mass ratio was66.38:26.2:7.42, the C/O ratio of etched fabrics was much lowerthan that of the superhydrophobic fabrics. The result can beexplained that O2 plasma treatment can etch away the attachedPFW/GF and produce oxygen containing hydrophilic groups on thecoating surface. The raised surface energy combined with highlyrough structure inherent explains the superhydrophilicity of etchedfabrics. While after being annealed at 110 C for 3 min, the C/O massratio (86.71:5.91) of the healing fabric increased significantly(Fig. 2b and Table S1). This result indicates that heat treatmentleads to PFW/GF attached on fibers or loaded in gaps restore theetched surface. Therefore, the damaged fabric regains its superhydrophobicitydue to the regenerated fresh surface on the fibers.3.3. Mechanical stability of the superhydrophobic fabricsWe then conducted the mechanical stability of the superhydrophobicfabrics via an abrasion test and a stretch test. Themethodology of the abrasion test is illustrated in Fig. 5a; thesuperhydrophobic fabric was subjected to a 4.1 kPa and kept closecontact with the sandpaper (1000 mesh served as an abrasionsurface). Then the fabric sample was dragged in one direction witha speed of 3 cm/s and abrasion length of 15 cm, respectively. Asshown in Fig. 5b, the CA changed slightly, while SA increasedgradually with increasing the abrasion cycles. This result showedthat SA is more sensitive than CA in evaluating wetting behavior ofthe samples after abrasion tests. This is because slight damage tothe coating may result in evident increase in adhesion force betweenthe coating and water droplets, and then the increased SAcan be detected. Fig. 5c showed that partial PFW/GF layer wasremoved after 600 scratch cycles, which result in a relative smoothsurface, whereas the rough structure still remained. Thus, the fabricremains its superhydrophobicity and water droplets still could rolloff the high tilted samples even after 600 scratch cycles. Theenhanced mechanical resistance results from strong attachment of
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