Date/Time: 04-05-2018 - Thursday - 05:00 PM - 07:00 PM
Yunheng Pei1 Liang Liu1 Timothy Singler1

1, State University of New York at Binghamton, Binghamton, New York, United States

The preparation of two-dimensional (2D) ordered micro/nanoparticle arrays holds significant potential for advanced functional material applications ranging from optoelectronic to biomedical devices. Various approaches have been reported in the literature to form ordered 2D particle arrays, including the particle self-assembly at the liquid-vapor (L-V) interface due to attractive interaction, particle monolayer formation on a solid substrate in a thin liquid film via capillary interaction, and deposition of particles on an electrode surface by electrostatic (or electrophoretic) forces. In this study, we focus on the large-scale fabrication of highly ordered particle monolayers on the L-V interface of a water layer. Silica particles of two different sizes were chosen as candidates: 0.5 and 1 μm in diameter, and the particles were coated with a polydopamine (PDA) capping layer. To investigate the influence of the particle hydrophobicity on the monolayer formation process, 1-dodecanethiol molecules were grafted on the outer surface of the PDA layer. Microliter suspension drops (1-butanol as solvent) of the coated particles were continuously added on the water surface, and the dispensing rate was controlled via a high-precision syringe pump. 2D ordered particulate films are gradually formed driven by the strong Marangoni convection. The resulting particle monolayer was carefully transferred to a solid substrate for morphological investigation. 2D hexagonal close-packed (HCP) particle arrays with a length scale of centimeters were observed. The results suggest that an appropriate degree of surface hydrophobicity of the particles is critical for the formation of a highly ordered particulate film structure. Monolayers with HCP morphology are favored when the particles are weakly hydrophobic, whereas films with particle agglomerates are favored when particles are strongly hydrophobic.

Meeting Program

5:00 PM–7:00 PM Apr 5, 2018

PCC North, 300 Level, Exhibit Hall C-E