Air-Stable Aerophobic Polydimethylsiloxane Tube with Efficient Self-Removal of Air Bubbles

Abstract

The adherence of underwater air bubbles to surfaces is a serious cause of malfunction in applications such as microfluidics, transport, and space devices. However, realizing spontaneous and additional unpowered transport of underwater air bubbles inside tubes remains challenging. Although superhydrophilic polydimethylsiloxane (PDMS) tubes are attracting attention as air bubble repellents, superhydrophilic PDMS, which is fabricated via oxygen plasma treatment, has a disadvantage in that it is weak against aging. Here, we present a tube with the ability to self-remove air bubbles, which overcomes the drawback of rapid aging. PDMS containing Silwet L-77 with a hierarchical nano–microstructure exhibiting subaqueous aerophobicity was fabricated. We conducted adherence and saturation experiments of air bubbles using the fabricated PDMS tube with Silwet L-77 to investigate the mechanism of bubbles adhering to and separating from the fabricated tube surface. The developed PDMS with Silwet L-77 exhibits a strong self-removal effect with an air bubble removal of 97.7%. The adherence and saturation experiments suggest that the transparent superhydrophilic–underwater aerophobic PDMS is a potentially exceptional tool for spontaneously separating air bubbles attached to tube surfaces.

3D Vascular Replicas Composed of Elastomer–Hydrogel Skin Multilayers for Simulation of Endovascular Intervention

“…The results were consistent with previous studies in that a hydrophilic surface becomes aerophobic underwater whereas a hydrophobic surface becomes aerophilic. [ 22,25,33 ] The superaerophobicity of the hydrogel skin‐coated PDMS can help prevent various problems due to the accumulated air bubbles trapped in the pipeline, including the disruption in fluid circulation, and image distortion due to the refractive index mismatch between air bubbles and DI water. Therefore, the hydrogel skin‐coated 3D vascular replicas are more suitable than their non‐coated counterpart for simulating endovascular intervention.…”

“…Elastomers, similar to tunica media, have high bulk elasticity [ 19 ] but exhibit high surface elasticity, [ 20 ] high friction, [ 21 ] and underwater aerophilicity. [ 22 ] Because of the high friction, additional lubricants, such as a surfactant solution, [ 23 ] liquid silicone rubber, [ 12 ] or specially designed slippery liquid, [ 24 ] are required to facilitate the control of medical devices. In addition, because of underwater aerophilicity, air bubbles can get trapped in the pipeline of the fluid and accumulate in the transport, causing the following problems: 1) obstruction of fluid circulation; [ 22,25 ] 2) visual distortion due to the refractive index mismatch between air bubbles and deionized (DI) water.…”

“…[ 22 ] Because of the high friction, additional lubricants, such as a surfactant solution, [ 23 ] liquid silicone rubber, [ 12 ] or specially designed slippery liquid, [ 24 ] are required to facilitate the control of medical devices. In addition, because of underwater aerophilicity, air bubbles can get trapped in the pipeline of the fluid and accumulate in the transport, causing the following problems: 1) obstruction of fluid circulation; [ 22,25 ] 2) visual distortion due to the refractive index mismatch between air bubbles and deionized (DI) water. [ 26 ] On the other hand, hydrogels, similar to tunica intima, have soft surface elasticity, [ 20 ] lubricity, [ 27 ] and underwater superaerophobicity, but exhibit slightly soft bulk elasticity [ 28 ] for use as a monolayer in 3D vascular replicas.…”

One-Step Eco-Friendly Superhydrophobic Coating Method Using Polydimethylsiloxane and Ammonium Bicarbonate

“…The roughened surface and low surface energy of the substrate allowed for superhydrophobicity to be achieved. 33 However, superhydrophobic properties cannot be imparted when insufficient quantities of the delivery components are formed or when the coating time is too short. To establish an optimal content of AB and optimal coating time, the wetting properties of the samples by varying amounts of AB and coating time were investigated (Figure 2).…”

One-Step Versatile Fabrication of Superhydrophilic Filters for the Efficient Purification of Oily Water

“…Several conventional techniques, such as gravity separation, coagulation, centrifugation, and flotation, have been used to purify oily water . However, such commercial techniques have disadvantages, including secondary pollution, low separation efficiencies, the inability to handle emulsified wastewater, and their time-consuming nature, which hinder the efficient remediation of wastewater. , Meanwhile, micro/nanoengineered surfaces with special wetting properties such as superhydrophobic surfaces showing a high contact angle (CA) above 150° and superhydrophilic surfaces showing a low CA below 10° can improve functional properties. − Hence, these kinds of surfaces have attracted interests in various fields, for example, self-cleaning, energy harvesting, water harvesting, and bubble nucleation applications. − Particularly, techniques for the purification of oily water that use filters with super-wetting properties have attracted significant levels of interest because they do not produce secondary pollution, consume little energy, and separate oil and water efficiently. − …”