A superhydrophobic steel surface was prepared through a facile method: combining hydrogen peroxide and an acid (hydrochloric acid or nitric acid) to obtain hierarchical structures on steel, followed by a surface modification treatment. Empirical grid maps based on different volumes of H2O2/acid were presented, revealing a wettability gradient from "hydrophobic" to "rose effect" and finally to "lotus effect". Surface grafting has been demonstrated to be realized only on the oxidized area. As-prepared superhydrophobic surfaces exhibited excellent anti-icing properties according to the water-dripping test under overcooled conditions and the artificial "steam-freezing" (from 50 °C with 90% humidity to the -20 °C condition) test. In addition, the surfaces could withstand peeling with 3M adhesive tape at least 70 times with an applied pressure of 31.2 kPa, abrasion by 400 grid SiC sandpaper for 110 cm under 16 kPa, or water impacting for 3 h without losing superhydrophobicity, suggesting superior mechanical durability. Moreover, outstanding corrosion resistance and UV-durability were obtained on the prepared surface. This successful fabrication of a robust, anti-icing, UV-durable, and anticorrosion superhydrophobic surface could yield a prospective candidate for various practical applications.
Fabrication
of reinforced scaffolds for bone regeneration remains
a significant challenge. The weak mechanical properties of the chitosan
(CS)-based composite scaffold hindered its further application in
clinic. Here, to obtain hydroxyethyl CS (HECS), some hydrogen bonds
of CS were replaced by hydroxyethyl groups. Then, HECS-reinforced
polyvinyl alcohol (PVA)/biphasic calcium phosphate (BCP) nanoparticle
hydrogel was fabricated via cycled freeze-thawing followed by an in vitro biomineralization treatment using a cell culture
medium. The synthesized hydrogel had an interconnected porous structure
with a uniform pore distribution. Compared to the CS/PVA/BCP hydrogel,
the HECS/PVA/BCP hydrogels showed a thicker pore wall and had a compressive
strength of up to 5–7 MPa. The biomineralized hydrogel possessed
a better compressive strength and cytocompatibility compared to the
untreated hydrogel, confirmed by CCK-8 analysis and fluorescence images.
The modification of CS with hydroxyethyl groups and in vitro biomineralization were sufficient to improve the mechanical properties
of the scaffold, and the HECS-reinforced PVA/BCP hydrogel was promising
for bone tissue engineering applications.
A suspension that can be sprayed onto substrates was developed to form a superhydrophobic/oleophilic surface. Lyophobic slippery surfaces were prepared by infusing perfluorinated lubricants into the superhydrophobic coating to repel almost all liquids with low surface tension values, including hexane, kerosene and diesel oil, showing a transition between superoleophilicity and lyophobicity. In addition, the travelling speeds of liquids appeared to be negatively correlated with the kinematic viscosity. In the anti-icing tests, the droplet was pinned after contacting a 0°C textured superhydrophobic surface for a few seconds because of the meniscus caused by the condensation of atmospheric humidity; by contrast, on the lyophobic slippery surface, a water droplet could easily slide even at-20°C, demonstrating superior icing resistance.
Highlights• The need for the modification of alginate properties was established • Click chemistry reactions were discussed • Functionality of using click chemistry for alginate-based materials was explored
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