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Jaebum Park,김형진 대한화학회 2016 대한화학회지 Vol.60 No.4
This paper describes the synthesis of alkali metal salts of urea (ureates) and their application to the direct preparation of 4-nitrosoaniline from nitrobenzene via nucleophilic aromatic substitution of hydrogen. Sodium and potassium ureates were readily prepared from the reaction of urea with sodium hydride, metal methoxides, and metal hydroxides. The effect of ureates as nucleophiles on the conversion of nitrobenzene to 4-nitrosoaniline was investigated and compared with that of a urea-metal hydroxide mixture. It was found that the ureates were superior for producing 4-nitrosoaniline owing to their higher thermal stability of the ureate. The ureate obtained from the treatment of urea with sodium hydride gave the highest yield for the preparation of 4-nitrosoaniline. The ureates generated from the reaction of urea with metal hydroxide also gave high yields of 4-nitrosoaniline. Catalytic hydrogenation of 4-nitrosoaniline afforded polymer-grade 1,4-benzenediamine in quantitative yield.
Jaebum Sung,Hoo Min Lee,Gil Ho Yoon,Sungchul Bae,Hongyun So 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.1
Polymer surfaces with wettability gradient were fabricated using three-dimensional (3D) printing technology to control the velocity of droplets on the surfaces. A microscale pattern of a semicircular casting mold was created layer-by-layer using a 3D printer based on fused deposition modeling. A surface with a wettability gradient was fabricated by replicating the semicircular mold with a continuously varying surface slope. Water contact angle measurements and droplet test results demonstrated the characterization of the wettability gradient. Droplets were released on a gradient surface inclined at 80°, and their movements were controlled; the locations of the droplets after collision on the ground were tracked. The distance of the main drop and splash drop was found to be reduced by 96.7% (from 6.1 to 0.2 cm) and 87.8% (from 18.8 to 2.3 cm), respectively, compared to that on a general superhydrophobic surface. This study demonstrates a simple, rapid, and inexpensive microfabrication method for functional polymer surfaces to control droplet movement using 3D printing technology.