Department of Chemistry and Biochemistry, Mount Allison University , 63C York Street, Sackville NB, Canada.
Langmuir. 2014 Jan 14;30(1):179-85. doi: 10.1021/la4037937. Epub 2013 Dec 20.
Nanoparticle films formed at the air-water interface readily form rigid films, where the nanoparticles irreversibly associate into floating "islands", often riddled with voids and defects, upon solvent evaporation. Improving the nanoparticle mobility in these films is key to achieving control over the nanoparticle packing parameters, which is attractive for a variety of applications. In this study, a variety of n-alkanes were mixed with tetradecanethiol-capped 2 nm gold nanoparticles and studied as Langmuir films at 18 and 32 °C. Pressure-area isotherms at 18 °C reveal a mixed liquid-expanded phase of nanoparticles and alkane at the air-water interface, but only for n-alkanes that are equal to or exceed the nanoparticle capping ligand in carbon chain length. Transmission electron microscopy images of the corresponding films suggest that the nanoparticles are mixed with a continuous hydrocarbon phase at 0 mN/m and that the hydrocarbon is squeezed out of the nanoparticle film during compression.
在空气-水界面形成的纳米粒子薄膜容易形成刚性薄膜，在溶剂蒸发时，纳米粒子不可逆地缔合成漂浮的“岛屿”，这些岛屿通常充满了空隙和缺陷。提高这些薄膜中纳米粒子的迁移率对于实现对纳米粒子堆积参数的控制至关重要，这对于各种应用具有吸引力。在这项研究中，各种正烷烃与十四硫醇封端的 2nm 金纳米粒子混合，并在 18°C 和 32°C 下作为朗缪尔膜进行研究。在 18°C 时的压力-面积等温线显示，在空气-水界面处存在纳米粒子和烷烃的混合液体膨胀相，但仅限于碳链长度与纳米粒子封端配体相等或超过的正烷烃。相应薄膜的透射电子显微镜图像表明，在 0mN/m 时纳米粒子与连续的碳氢化合物相混合，并且在压缩过程中碳氢化合物从纳米粒子膜中挤出。
