Icing of surfaces has become a serious issue, and effective methods for preventing ice accretion have received much attention in recent years. Here, a solvent volatilization-induced cross-linking hydroxy-terminated dimethylsiloxane (Si−OH) coating with tetramethoxysilane (TMOS) as a cross-linker is proposed for large-scale deicing applications. Interfacial adhesion tests and shear force analysis were conducted to confirm the large-scale deicing properties of the polydimethylsiloxane (PDMS) coating. Through characterization of morphology, it was found that there were negative correlations between roughness and constant shear force and shear strength. The mean constant shear force per unit width could be lower than 14 N/cm when the roughness was in the highest range fabricated in this research. In addition to the morphology of the surface, the mass ratio of the cross-linker to the premonomer affected the state of the surface and the deicing properties. When the mass ratio was lowered, uncross-linked molecular chains of the premonomer existed on the surface, which resulted in an increase in interfacial toughness and a reduction in shear strength. Finally, durability tests showed that the coating had excellent durability and could endure at least 50 cycles without an apparent increase in the constant shear force.
Recently, low interfacial toughness (LIT) materials have
been developed
to solve large-scale deicing problems. According to the theory of
interfacial fracture, ice detachment is dominated by strength-controlled
or toughness-controlled regimes, which are characterized by adhesive
strength or constant shear force. Here, a new strategy is introduced
to regulate the interfacial toughness of poly(dimethylsiloxane) (PDMS)
coatings using silicon dioxide nanoparticles (SiO2 NPs)
and phenylmethyl silicone oil (PMSO). By systematically adjusting
the doping proportion of SiO2 NPs and PMSO, it is found
that a lower interfacial toughness can be achieved with a lower constant
shear force. The synergistic effect of the two dopants on the adhesive
strength and interfacial toughness is analyzed. Meanwhile, finite
element method (FEM) analysis of ice detachment is conducted to show
the cracking process intuitively and explicate the mechanism of lowering
the interfacial toughness of PDMS by doping SiO2 NPs and
PMSO. It can be concluded that the cohesive zone material (CZM) model
is effective for simulating the deicing process of PDMS coatings and
provides a comprehensive understanding of the modulation of interfacial
toughness.
Intelligent surfaces with reversibly switchable wettability
have
recently drawn considerable attention. One typical strategy to obtain
such a surface is to change the surface chemistry or the microstructure.
Herein, we report a new smart surface for which the wettability was
controlled by both the surface chemistry and microstructure. Various
wetting states were reversibly and precisely controlled through heating,
pressing, NIR irradiation, and oxygen plasma treatment. The excellent
shape memory characteristics of shape memory polyurethane (SMPU) and
the controlled release of hydrophobic/hydrophilic oxygen-containing
functional groups contributed to this ability. Microcapsules were
used to design these smart surfaces. They controlled the release
of a fluorinated alkyl silane (FAS) through shell melting, changed
the surface composition, and played a decisive role in protecting
the FAS against hydrolysis and evaporation to ensure that the surface’s
wettability is recyclable. Controlling of the surface chemistry or
microstructure was repeated for at least 19 or 16 cycles, respectively,
which indicated excellent repeatability compared to other smart surfaces.
Based on the excellent controllability, the surface exhibited multiple
functions, such as liquid directional transport and coefficient of
friction control. In addition, it maintained this extraordinary ability
under harsh environments owing to the great stability of the SMPU
and adequate protection of the FAS by the microcapsules. With switchable
wettability based on the surface chemistry and microstructure, this
work provides a new principle for designing smart surfaces with wettability
controlled in two ways.
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