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

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.

水下气泡对表面的附着是微流控、运输以及空间设备应用中故障的重要原因。然而，在管道内实现水下气泡的自主和无动力运输仍然是一项挑战。尽管超亲水聚二甲基硅氧烷（PDMS）管因其在空气泡排斥方面的潜力而受到关注，但通过氧气等离子体处理制备的超亲水PDMS存在抗老化能力弱的缺点。在本研究中，我们展示了一种能够自我去除气泡的管材，克服了快速老化的缺陷。我们制备了一种含有Silwet L-77的PDMS，该PDMS具有分级纳米-微结构，表现出水下疏水性。我们使用含有Silwet L-77的制备PDMS管进行了气泡附着和饱和实验，以探究气泡附着和从制备管表面分离的机制。含有Silwet L-77的PDMS表现出97.7%的气泡去除效果，显示出强烈的自我去除作用。附着和饱和实验表明，透明超亲水-水下疏水PDMS可能是分离附着于管表面的气泡的潜在优异工具。