Ultrafast Flame-Induced Pyrolysis of Poly(dimethylsiloxane) Foam Materials toward Exceptional Superhydrophobic Surfaces and Reliable Mechanical Robustness

Abstract

Superhydrophobic surfaces are imperative in flexible polymer foams for diverse applications; however, traditional surface coatings on soft skeletons are often fragile and can hardly endure severe deformation, making them unstable and highly susceptible to cyclic loadings. Therefore, it remains a great challenge to balance their mutual exclusiveness of mechanical robustness and surface water repellency on flexible substrates. Herein, we describe how robust superhydrophobic surfaces on soft poly­(dimethylsiloxane) (PDMS) foams can be achieved using an extremely simple, ultrafast, and environmentally friendly flame scanning strategy. The ultrafast flame treatment (1–3 s) of PDMS foams produces microwavy and nanosilica rough structures bonded on the soft skeletons, forming robust superhydrophobic surfaces (i.e., water contact angles (WCAs) > 155° and water sliding angles (WSAs) < 5°). The rough surface can be effectively tailored by simply altering the flame scanning speed (2.5–15.0 cm/s) to adjust the thermal pyrolysis of the PDMS molecules. The optimized surfaces display reliable mechanical robustness and excellent water repellency even after 100 cycles of compression of 60% strain, stretching of 100% strain, and bending of 90° and hostile environmental conditions (including acid/salt/alkali conditions, high/low temperatures, UV aging, and harsh cyclic abrasion). Moreover, such flame-induced superhydrophobic surfaces are easily peeled off from ice and can be healable even after severe abrasion cycles. Clearly, the flame scanning strategy provides a facile and versatile approach for fabricating mechanically robust and surface superhydrophobic PDMS foam materials for applications in complex conditions.

Superhydrophobic VO2 Nanoparticle/PDMS Composite Films as Thermochromic, Anti-icing, and Self-Cleaning Coatings

“…In general, the stripe-VO 2 /PDMS films with relatively high surface roughness are insufficiently strong to resist mechanical wear and harsh environments, presenting destroyed surface structures and deteriorated antiwetting performance. 63 Developing a mechanically robust functional surface is therefore of more significance for practical applications. In this work, the mechanical durability of the stripe-VO 2 /PDMS film was estimated by monitoring the changes in the WCA and ΔT sol after three representative mechanical robustness tests, including the tape test, sand abrasion test, and sponge washing test.…”

Humidity-Responsive Actuators Based on Firm Heterojunction of Glycerol-Cross-linked Polyvinyl Alcohol and Porous Polyvinylidene Fluoride as Smart Gates for Anti-condensation

“…The plasma-treated PVDF films are coded as PVDF-M. As expected, after surface modification by plasma treatment, the water contact angle of PVDF0 film decreases from 93.8 to 49.5°, that of the PVDF0.1 film decreases from 121 to 90.3°, and that of the PVDF0.45 film decreases from 122.7 to 89.1° (Figure a). Compared with the smooth surfaces, the micro-/nanostructures on rough surfaces reduce the liquid–solid contact, resulting in the increase of water contact angles on the solid surfaces according to the Wenzel wetting model. − Therefore, the water contact angles of porous PVDF0.1 and PVDF0.45 films with rough surface structures are larger than that of the dense PVDF0 film with a smooth surface structure, although the intrinsic wettability of PVDF material is the same. The experimental results show that the surface wettability of all the dense and porous PVDF films are efficiently enhanced by the plasma treatment.…”

Facile Construction and Fabrication of a Superhydrophobic and Super Oleophilic Stainless Steel Mesh for Separation of Water and Oil

“…The cost-effective separation strategies of oil/water mixtures have become a hot topic due to the frequent occurrences of water pollution issues, such as organic wastewater emissions, chemical leaks, and crude oil spills [ 1 , 2 , 3 , 4 ]. To date, a series of materials, including carbon aerogels [ 5 , 6 , 7 , 8 ], cotton fabrics [ 9 , 10 , 11 , 12 ], foams [ 13 , 14 , 15 ], and sponges [ 16 , 17 , 18 , 19 ], have been explored, owing to the excellent hydrophobicity and high separation capacity. However, some materials are difficult to use in large-scale applications because of the complicated and high-cost separation process, secondary contamination, or poor recyclability.…”