• Composites Research
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• v.20 no.2
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• pp.17-20
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• 2007

Superhydrophobic polytetrafluoroethylene ($Teflon^{(R)}$, Dupont) sub-micro and nanostructures were fabricated by the dipping method, based on anodization process in oxalic acid. The polymer sticking phenomenon during the replication creates the sub-microstructures on the negative polytetrafluoroethylene nanostructure replica. This process gives a hierarchical structure with nanostructures on sub-microstructures, which looks like the same structures as lotus leaf and enables commercialization. The diameter and the height of the replicated nano pillars were 40 nm and 40 um respectively. The aspect ratio is approximately 1000. The fabricated surface has a semi-permanent superhydrophobicity, the apparent contact angle of the polytetrafluoroethylene sub-micro and nanostructures is about $160^{\circ}$, and the sliding angle is less than $1^{\circ}$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.77-83
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• 2022

When carbon dioxide in a liquid becomes supersaturated, carbon dioxide gas bubbles are generated in the liquid, and they ascend to the surface as they develop further. At this time, the inner wall of the cup with carbon gas attached is known as the entrapped gas cavity (EGS); once an EGS is established, it does not disappear and will continuously create carbon bubbles. This bubbling phenomenon can be activated or suppressed by changing the properties of the solid surface in contact with the carbonated liquid. In this study, the foaming of carbonated liquid is promoted or suppressed by modifying the wettability of the surface. A micro/nano surface structure is formed on the surface of an aluminum cup to produce a superhydrophilic surface, and a superhydrophobic surface similar to a lotus leaf is synthesized via fluorination. Experiment results show that the amount of carbon dioxide bubble generated differs significantly in the first few seconds depending on the surface, and that the amount of gas generated after it enters the stabilization period is the same regardless of the wettability of the cup surface.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.34-34
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• 2012

Polypropylene 섬유는 세계적으로 큰 관심을 모으고 있는 섬유 소재로 환경친화성, 경량성, 신축성 등 다양한 기능성을 보유하여 미국, 일본 등의 선진국에서 의류 및 인테리어용으로 채택하여 널리 사용되고 있다. 그러나, polypropylene 섬유는 다른 섬유에 비해 융점이 매우 낮아 내열성이 약하여 가공 공정시 고온을 피해야 하고, 곁가지가 거의 없고 섬유 분자 구조가 매우 조밀하며 탄소와 수소로만 이루어진 분자구조에 의한 극소수성 성질 때문에 다른 종류의 물질들과 접착력이 없어 사용에 제약을 주어 다양한 용도로의 활용이 제한되고 있는 실정이다. 본 연구에서는 Polypropylene 섬유의 제품화에 필요한 요소 기술의 기초를 마련하고자 대기압 플라즈마를 적용하여 소수성 표면을 지니는 표면을 친수화 함으로써 polypropylene 섬유에 후가공이 가능하도록 한다. 따라서 Plasma 표면 처리에 의해 polypropylene 섬유에 미치는 영향에 대하여 조사하고, 표면을 친수화 함으로써 습윤성, 접착성 등 다양한 가공 기술을 적용하여 PP 섬유의 기능성을 향상시키고자 한다. 플라즈마 처리에 의한 폴리프로필렌 섬유의 모폴로지 변화는 주사전자현미경 (FE-SEM)으로 확인하였으며 표면개질 효과는 Wicking Test로 평가하였다.

• Environmental Analysis Health and Toxicology
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• v.20 no.4 s.51
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• pp.351-358
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• 2005

The n -octanol/water partition coefficient (Pow) is one of the most important parameters employed for estimating a chemiral's environmental fate and toxicity. The shake-flask method, one direct experimental method, i.1 prone to experimental artifacts for highly hydrophobic compounds. Thus, a valid method for direct determination of the Pow of highly hydrophobic compounds is needed. The slow -stirring method has been demonstrated to provide reliable log Pow data to log Pow greater than 5. This study was performed to evaluate the accuracy of slow- stirring experiment for determination of log Pow, particularly for highly hydrophobic compounds. 1, 2, 3, 4-tetrachlorobenzene, hexachlorobezene, 2, 2', 3, 3', 5, 5', 6, 6'-octachlorobiphenyl, decachlorobiphenyl, and p, p'-DDT (4.5$\times$0.02, 5.41$\times$0.06, 7.26$\times$0.04, 7.87$\times$0.10, and 6.03$\times$0.06, respectively. The octanol/water partition coefficient by the slow-stirring method were very similar to the literature values. These results indicate that the slow- stirring method allows for reliable determination of log Pow of highly hydrophobic chemicals.