Self-Formation of Superhydrophobic Surfaces through Interfacial Energy Engineering between Liquids and Particles

Abstract

The superhydrophobic surface has been used in ultradry surface applications, such as the maritime industry, windshields, non-sticky surfaces, anti-icing surfaces, self-cleaning surfaces, and so forth. However, one of the main hurdles for the production of superhydrophobic surfaces is highcost fabrication methods. Here, we report a handy process of self-synthesis fabrication of superhydrophobic surfaces with daily supplies. Driven by the physics of biscuit dunking, we introduce a method to self-synthesize superhydrophobic surfaces from daily supplies by coating a substrate with a liquid (liquids of paraffin from candles or polydimethylsiloxane) and subsequently sprinkling powders (food-desiccant silica, alumina, sugar, salt, or flour). A mechanistic study revealed that the capillary force, governed by surface energy difference, liquid viscosity, and powder pore size, draws the liquid solution into the porous channels within the powders. The entire surface of powders, in turn, is covered with the low-surface-energy liquid to maintain the porosity, creating a 3D porous nanostructure, resulting in a water contact angle over 160°. This work provides a scientific understanding that technological developments are closely related to the science that can be seen in our daily lives. Also, we believe that further intensive studies extended from this work could enable to home-fabricate a superhydrophobic surface, such as a bathtub and sink in bathrooms and a cooking area and sink in kitchens.

Near-Infrared Responsive Smart Superhydrophobic Coating with Self-Healing and Robustness Enhanced by Disulfide-Bonded Polyurethane

“…In summary, the results show that the PU molecular chains can be thermally activated at a certain temperature, by which the PU itself could be destabilized and the long-term stability of the composite coating weakened. We speculated that the possible reason was mainly the increased fluidity of the molecular chain of PU itself by thermal activation, resulting in the gradual penetration of surface particles into PU by gravity of the composite particles and capillary absorption of PU molecular chains , and subsequent damage or even destruction of the composite coating surface rough structure. In order to confirm the speculation, the surface roughness of the samples was studied after being stored at three temperatures for 240 h. Figures S6–S8 show the arithmetic mean roughness ( S a ) of three PU specimens at 30, 50, and 70 °C for 240 h, respectively.…”

Icephobic Coating through a Self-Formed Superhydrophobic Surface Using a Polymer and Microsized Particles

“…After the PDMS solution was uniformly coated, SiO 2 powder (Sigma-Aldrich, average powder size of 5.4 μm, irregular shape) was sprinkled using a 200-mesh sieve to cover the substrate uniformly. The sample was then placed at room temperature (24 °C and 60% humidity) for 10 min to promote the self-formation process of PDMS and SiO 2 powder as described in our previous paper . The SiO 2 /PDMS-coated substrate was baked in an oven at 80 °C for 3 h for curing, and the unreacted SiO 2 powder was removed by nitrogen blowing.…”

“…Polydimethylsiloxane (PDMS) is the most widely studied material owing to its low ice adhesion and anti-icing properties that result from its low surface energy, hydrophobicity, viscoelasticity, nontoxicity, low cost, and ease of use. Recently, we developed an efficient and one-step cost-effective method for preparing superhydrophobic surfaces using PDMS and SiO 2 powders . When the SiO 2 powder was sprinkled on PDMS, it was spontaneously coated by PDMS through the biscuit dunking effect described by Washburn’s equations and Stokes’ law.…”

One-Step Fabrication of a Functionally Integrated Device Based on Polydimethylsiloxane-Coated SiO2 NPs for Efficient and Continuous Oil Absorption

“…Second, the PDMS precursor was prepared by mixing the PDMS base and the curing agent in a 10:1 weight ratio. Then the PDMS precursor, SiO 2 NPs, and heptane solvent were mixed together in a dilution ratio 1 (i.e., 0.3 g SiO 2 NPs: 0.2 g PDMS: 20 mL heptane) [ 33 , 34 , 35 ], before an ultrasonic treatment for 15 min was conducted to form a suspension. The dilution ratio was 0.5, 1.5, 2, and 2.5 when 10, 30, 40, and 50 mL heptane was added with the same amount of SiO 2 NPs and the PDMS precursor ( Figures S2 and S3 ).…”