Figure 2. (A) The coated glass exhibited an optical
transmission close to that of its uncoated counterpart. (B) Photograph
of a smartphone screen covered by the coated glass in the middle region
that is outlined by white dashed lines. (C) AFM image of the coating
surface. (D) Photograph of the minimum bending radius measurement of the
coated PET. (E) The coating maintained its anti-adhesion performance
against oil-based ink after it had been subjected to 1000 abrasion
cycles. (F) Antiadhesion performance against oil-based ink after the
coatings had been immersed into NaOH (pH = 14), HCl (pH = 0), and NaCl
solutions (10 wt%) for 7 h, 16 h, and 15 d, respectively. (G) The
sliding behaviour of cooking oil before and after the coating had been
immersed in this oil for 15 d. (H) The CAs of various liquids exhibited
negligible changes after the coatings had been immersed in these liquids
for various lengths of time.
The coating also possesses excellent transparency, flexibility, and
durability. The optical transmission of uncoated and coated glass slides
exhibited negligible differences in the visible light range (400-750 nm,
Fig. 2A). The glass slide bearing the transparent coating did not
obscure the screen (Fig. 2B), indicating its potential applicability for
electronic displays or devices. This optical clarity could be attributed
to the flatness of the coating surface, thanks to the excellent
miscibility of the silicon precursors and the lack of solvent
volatilization disturbance in this solvent-free system. The atomic force
microscopy (AFM, Fig. 2C) image indicated that the root-mean-square
surface roughness was only ~ 0.5 nm, while the SEM (Fig.
S4) image revealed that the coating possessed a featureless surface with
no evidence of structures or roughness above the micrometer scale. A
minimum bending radius of less than 1 mm was reached for the coated PET
(Fig. 2D). This excellent flexibility and foldability would expand a
diverse range of coating applications, including the coating of soft
pipelines, as well as flexible materials or devices for prosthetics and
advanced robotics. The coating possessed a hardness rating of HB
according to the ASTM D3363 protocol, and the oil-based ink could still
be completely removed from the coating even after it had been subjected
to 1000 abrasion cycles with cotton fabric under a load of 500 g (Fig.
2E). The coatings maintained their long-term anti-adhesion performances
even after they had been immersed in basic, acidic, salt solutions, and
oil (Fig. 2F and G). The negligible chemical change of the coating
surface after the immersion in different liquids for various lengths of
time has been confirmed via CA measurements (Fig. 2H) and XPS (Fig. S7).
With the high crosslinking density that is induced by the low molecular
weight of processors, the migration of interfacial segments as well as
the chemical reconstruction at the interfaces of the coating and ambient
liquids would be restrained.