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Correction for ‘A robust and flexible bulk superhydrophobic material from silicone rubber/silica gel prepared by thiol–ene photopolymerization’ by Yongsheng Li et al., J. Mater. Chem. A, 2019, DOI: 10.1039/c8ta11111a.

Building a superhydrophobic coating on polymer films is an important way to obtain water-proof surfaces. However, due to the poor mechanical strength and weak adhesion between coating and substrate, the superhydrophobicity of the coating is easily lost under mechanical loads. In this study, a facile approach was proposed to build a mechanically stable superhydrophobic poly(chloro-p-xylylene) (PPXC) film by pre-coating a polydimethylsiloxane adhesive layer (PDMS AL) on the original PPXC film and coating a superhydrophobic PDMS and silica (PDMS/SiO2) layer on the PDMS AL layer. As demonstrated by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) measurements, the thermal cross-linking reaction between the PDMS/SiO2 coating and the PDMS AL layer could dramatically promote the interaction between the PDMS/SiO2 coating and the PPXC film. By tuning pre-curing time and the content of PDMS AL, the mechanical stability of the PDMS/SiO2 coating on PPXC film could be adjusted. Under the optimal conditions of pre-curing time and the content of PDMS AL, the PPXC film showed robust superhydrophobicity and self-cleaning ability against various mechanical damages, such as 3M tape peeling and cyclic abrasion. The superhydrophobic coating on PPXC film with PDMS AL showed a higher peeling resistance than that on PPXC film without PDMS AL. Moreover, the superhydrophobic coating on PPXC film with PDMS AL maintained its original superhydrophobicity even after 4000 cycles of abrasion.

To fabricate mechanically stable superhydrophobic surfaces, conventional methods often involve complicated and time-consuming processing to improve the interface adhesion between coating and substrate, such as multi-step pre-treatments of the substrate and long time post-curing for both substrate and coating. Here, we report a facile and fast method to prepare the robust and stretchable superhydrophobic surface by rapid UV cross-linking of the superhydrophobic coating (based on polydimethylsiloxane/silica composite) onto a stretchable substrate. Polyurethane acrylate (PUA) with double bonds was UV cured to form the stretchable elastomeric substrate, the surface of which remains uncured PUA due to the presence of oxygen inhibition. The oxygen-inhibited layer of the substrate can provide a lot of reactive sites for covalently bonding to the superhydrophobic coating under UV exposure and thus eliminates the requirement for complicated surface treatments of the substrate. The formed covalent cross-linking between the superhydrophobic coating and the PUA substrate facilitates their interface adhesion. As expected, the superhydrophobic coating covalently-bonded to the PUA substrate shows good superhydrophobicity and self-cleaning ability against mechanical abrasion and stretching damages. Besides, the resulting superhydrophobic surface can withstand 1000-cycle stretching-releasing (strain of 0% → 200% → 0%) without losing its original superhydrophobicity. Thus, this robust superhydrophobic surface could find a wide range of water-proof applications for flexible substrates such as stretchable electronics, functional textiles, and outdoor sport goods.

Enhancing surface wetting is very critical for various applications of polymer films. Although existing modification methods (e.g., UV radiation and plasma treatments) can improve the wetting of polymer films by inserting hydrophilic groups, the resultant polymer surface is unstable and shows strong hydrophobic recovery in a short time (less than 1 day) due to the rearrangement of the polymer chains. Herein, we report a new approach to prepare stable wetting surface by cross-linking hydrophilic poly(acrylic acid) (PAA) molecules on poly(chloro-p-xylylene) (PPXC) films via hyperthermal hydrogen induced cross-linking (HHIC) treatment. With the HHIC treatment, the polar functionalities of PAA (e.g., −COOH) can be preserved through selective cleavage of C–H bonds and subsequent cross-linking of resulting carbon radicals generated on PAA and PPXC chains. HHIC-treated PAA–PPXC film shows an excellent wetting stability, of which WCA and surface energy stay almost the same over 40 days. The improved wetting stabi...

Poly(chloro-p-xylylene) (PPXC) film has a water contact angle (WCA) of only about 84°. It is necessary to improve its hydrophobicity to prevent liquid water droplets from corroding or electrically shorting metallic circuits of semiconductor devices, sensors, microelectronics, and so on. Herein, we reported a facile approach to improve its surface hydrophobicity by varying surface pattern structures under different temperature and relative humidity (RH) conditions on a thermal curable polydimethylsiloxane (PDMS) and hydrophobic silica (SiO2) nanoparticle coating. Three distinct large-scale surface patterns were obtained mainly depending on the contents of SiO2 nanoparticles. The regularity of patterns was mainly controlled by the temperature and RH conditions. By changing the pattern structures, the surface wettability of PPXC film could be improved and its WCA was increased from 84° to 168°, displaying a superhydrophobic state. Meanwhile, it could be observed that water droplets on PPXC film with superhydrophobicity were transited from a “Wenzel” state to a “Cassie” state. The PPXC film with different surface patterns of 200 μm × 200 μm and the improved surface hydrophobicity showed wide application potentials in self-cleaning, electronic engineering, micro-contact printing, cell biology, and tissue engineering.

Polymer barrier materials have been increasingly used in many applications such as metal anti-corrosion, electronic packaging, and cultural relic protection, but they have poor resistance to water vapor compared to inorganic barrier materials. Herein, we demonstrate the first application of hyperthermal hydrogen induced cross-linking (HHIC) technology to improve dramatically the water vapor barrier properties of poly(chloro-p-xylylene) (PPXC) films by building a dense and intact surface cross-linking layer. With the HHIC treatment, a dense cross-linked layer is formed on the surface of the PPXC film, which serves as a dense barrier layer to water vapor diffusion. The water vapor transmission rate of the PPXC film sharply decreases from 8.4 × 10−16 to 2.1 × 10−16 g cm cm−2 s−1 Pa by 75% after 5 min HHIC treatment. Due to the advantage of selective cleavage of C–H bonds by HHIC treatment, the desired chloride groups and original physical properties (e.g. mechanical strength and light transmittance) were well preserved.