Figure 1. (A) CAs, SAs, and CA hysteresis of various test liquids on the coatings. The inset image demonstrates the sliding behaviour of hexadecane. (B) Anti-adhesion performance against oil-based ink exhibited by the coatings on various substrates. (C) The tapes could be readily removed from the coating surfaces, while were damaged and left residuals for the uncoated substrates. (D,E) The tensile strength and shear strength between the adhesives and the coating as well as various uncoated substrates.
To evaluate the anti-adhesion properties of the coating, liquids with various surface tensions such as water, diiodomethane, hexadecane, and ethanol (72.8, 50.8, 27.5, and 22.1 mN/m, respectively at 20 °C), as well as oils with different viscosities such as cooking oil, pump oil, and crude oil (~80, 200, and 300 cP, respectively at 20 °C) were used for the CAs, SAs, and CA hysteresis measurements. As shown in Fig. 1A, the coating displayed low SAs and CA hysteresis toward all of these test liquids. These simple and complex liquids could be repelled and readily slid off the tilted coating surfaces without leaving any residues. When the HO-PDMS-OH was covalently linked into the network to generate a lubricating segment, it no longer exhibited a liquid state at the macroscopic level. Meanwhile, the glass transition temperature of the coating as determined via differential scanning calorimetry (DSC) experiments was ~ -35 °C, implying that the polymer chains with abundant lubricating segments could be stretched and rotated readily at room temperature and provide the desired liquid-like interfacial anti-adhesion behavior (Fig. S5).
Moreover, the oil-based ink traces of Sharpie markers readily contracted on a diverse range of coated substrates (Fig. 1B), including hard, thermosensitive, and flexible materials such as glass, metal, wood, paper, and polyethylene terephthalate (PET). The shrunken ink traces could be readily wiped away with dry tissues. In contrast, it was difficult to remove the ink from the uncoated regions of the substrates. Noteworthy, the coating was found to exhibit low adhesion against viscoelastic and sticky adhesives. The adhesive tapes could be readily removed from the coating surfaces, and thus ensure the cleanability of substrates as well as the recyclability of adhesives and advertisement papers (Fig. 1C). Pieces of 3M Scotch® double-sided mounting tape and adhesive tape were applied onto the coating and various uncoated substrates to evaluate the tensile strength and shear strength (Fig S6).21 As shown in Fig. 1D and E, these tapes could be removed from the coatings with the tensile strength of ~42 kPa and negligible shear strength, and the values were far lower than those estimated for the uncoated substrates.