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Bioinspired polymer microstructures for directional transport of oily liquids

View Article: PubMed Central - PubMed

ABSTRACT

Nature has always served as an inspiration for scientists, helping them to solve a large diversity of technical problems. In our case, we are interested in the directional transport of oily liquids and as a model for this application we used the flat bug Dysodius lunatus. In this report, we present arrays of drops looking like polymer microstructures produced by the two-photon polymerization technique that mimic the micro-ornamentation from the bug's cuticle. A good directionality of oil transport was achieved, directly controlled by the direction of the pointed microstructures at the surface. If the tips of the drop-like microstructures are pointing towards the left side, the liquid front moves to the right and vice versa. Similar effects could be expected for the transport of oily lubricants. These results could, therefore, be interesting for applications in friction and wear reduction.

No MeSH data available.


Related in: MedlinePlus

Different radii of the drop-like microstructures as defects on the glass slide surface. The smaller radius r1 is about 2 µm and the larger radius r2 is about 4.5 µm.
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RSOS160849F7: Different radii of the drop-like microstructures as defects on the glass slide surface. The smaller radius r1 is about 2 µm and the larger radius r2 is about 4.5 µm.

Mentions: As can be seen from figure 7, the smaller radius r1 of our microstructures is about 2 µm, while the larger radius r2 is about 4.5 µm. The average distance L between the defects is approximately 13 µm. The fraction in the above formula is constant for the given material combination, but the logarithm of L/r is different for the two transport directions by a factor of approximately 2. Thus, the liquid flows and increases the contact angle at the fronts until the advancing contact angle is reached and then the liquid jumps. While at the larger radius r2 the advancing contact angle is overcome and the liquid front jumps, the small radius r1 pins the front better and due to the jump in the direction of r2, increasing the apparent wetted area, the contact angles are decreased again. This can be observed repetitively until the one side of the structure is completely filled with liquid. Then the flowing liquid can increase the contact angle at the sides of r1 and also overcome the pinning. When the oil front moves transversally to the microstructures (i.e. down in the figures), it encounters defects with even much larger radii (almost infinite) than both r1 and r2. According to the formula, this should result in less pinning making the liquid front move faster, as is observed experimentally.Figure 7.


Bioinspired polymer microstructures for directional transport of oily liquids
Different radii of the drop-like microstructures as defects on the glass slide surface. The smaller radius r1 is about 2 µm and the larger radius r2 is about 4.5 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383830&req=5

RSOS160849F7: Different radii of the drop-like microstructures as defects on the glass slide surface. The smaller radius r1 is about 2 µm and the larger radius r2 is about 4.5 µm.
Mentions: As can be seen from figure 7, the smaller radius r1 of our microstructures is about 2 µm, while the larger radius r2 is about 4.5 µm. The average distance L between the defects is approximately 13 µm. The fraction in the above formula is constant for the given material combination, but the logarithm of L/r is different for the two transport directions by a factor of approximately 2. Thus, the liquid flows and increases the contact angle at the fronts until the advancing contact angle is reached and then the liquid jumps. While at the larger radius r2 the advancing contact angle is overcome and the liquid front jumps, the small radius r1 pins the front better and due to the jump in the direction of r2, increasing the apparent wetted area, the contact angles are decreased again. This can be observed repetitively until the one side of the structure is completely filled with liquid. Then the flowing liquid can increase the contact angle at the sides of r1 and also overcome the pinning. When the oil front moves transversally to the microstructures (i.e. down in the figures), it encounters defects with even much larger radii (almost infinite) than both r1 and r2. According to the formula, this should result in less pinning making the liquid front move faster, as is observed experimentally.Figure 7.

View Article: PubMed Central - PubMed

ABSTRACT

Nature has always served as an inspiration for scientists, helping them to solve a large diversity of technical problems. In our case, we are interested in the directional transport of oily liquids and as a model for this application we used the flat bug Dysodius lunatus. In this report, we present arrays of drops looking like polymer microstructures produced by the two-photon polymerization technique that mimic the micro-ornamentation from the bug's cuticle. A good directionality of oil transport was achieved, directly controlled by the direction of the pointed microstructures at the surface. If the tips of the drop-like microstructures are pointing towards the left side, the liquid front moves to the right and vice versa. Similar effects could be expected for the transport of oily lubricants. These results could, therefore, be interesting for applications in friction and wear reduction.

No MeSH data available.


Related in: MedlinePlus