Uda Makoto, Kawashima Hisato, Mayama Hiroyuki, Hirai Tomoyasu, Nakamura Yoshinobu, Fujii Syuji
Division of Applied Chemistry, Graduate School of Engineering, Osaka Institute of Technology, 5-16-1, Omiya, Asahi-ku, Osaka 535-8585, Japan.
Department of Chemistry, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa 078-8510, Japan.
Langmuir. 2021 Apr 13;37(14):4172-4182. doi: 10.1021/acs.langmuir.1c00041. Epub 2021 Mar 31.
Micrometer-sized hydrophobic polyaniline (PANI) grains were synthesized via an aqueous chemical oxidative polymerization protocol in the presence of dopant carrying perfluoroalkyl or alkyl groups. The critical surface tensions of the PANIs synthesized in the presence of heptadecafluorooctanesulfonic acid and sodium dodecyl sulfate dopants were lower than that of PANI synthesized in the absence of dopant, indicating the presence of hydrophobic dopant on the grain surfaces. The PANI grains could adsorb to air-liquid interfaces, and aqueous and nonaqueous liquid marbles (LMs) were successfully fabricated using liquids with surface tensions ranging between 72.8 and 42.9 mN/m. Thermography studies confirmed that the surface temperature of the LMs increased by near-infrared light irradiation thanks to the photothermal property of the PANI, and the maximum temperatures measured for nonaqueous LMs were higher than that measured for aqueous LM. We demonstrated that transport of the LMs on a planar water surface can be achieved via Marangoni flow generated by the near-infrared light-induced temperature gradient. Numerical analyses indicated that the LMs containing liquids with lower specific heat and thermal conductivity and higher density showed longer path length per one light irradiation shot and longer decay time. This is because generated heat could efficiently transfer from the LMs to the water surface and larger inertial force could work on the LMs. The LMs could also move over the solid substrate thanks to their near-spherical shapes. Furthermore, it was also demonstrated that the inner liquids of the LMs could be released on site by an external stimulus.
通过在携带全氟烷基或烷基的掺杂剂存在下的水相化学氧化聚合方法合成了微米级疏水聚苯胺（PANI）颗粒。在十七氟辛烷磺酸和十二烷基硫酸钠掺杂剂存在下合成的聚苯胺的临界表面张力低于在无掺杂剂情况下合成的聚苯胺的临界表面张力，这表明颗粒表面存在疏水性掺杂剂。聚苯胺颗粒可以吸附到气 - 液界面，并且使用表面张力在72.8至42.9 mN/m之间的液体成功制备了水性和非水性液体弹珠（LM）。热成像研究证实，由于聚苯胺的光热特性，近红外光照射使液体弹珠的表面温度升高，并且非水性液体弹珠测量的最高温度高于水性液体弹珠测量的最高温度。我们证明了通过近红外光诱导的温度梯度产生的马兰戈尼流可以实现液体弹珠在平面水表面上的运输。数值分析表明，含有比热和热导率较低且密度较高的液体的液体弹珠在每次光照射时显示出更长的路径长度和更长的衰减时间。这是因为产生的热量可以有效地从液体弹珠传递到水表面，并且更大的惯性力可以作用在液体弹珠上。由于其近球形形状，液体弹珠也可以在固体基质上移动。此外，还证明了液体弹珠的内部液体可以通过外部刺激现场释放。
