5:30 PM - 5:45 PM
△ [14p-313-16] Flattening Water Droplets by Polydopamine Membranes on Air/Water Interface
Keywords:polydopamine, air / water interface, membranes
Dopamine plays various roles in nature, such as adhesion proteins, neurotransmitters, and pigments. Recently, polydopamine can be easily formed by the auto oxidation, and polydopamine is expected to the material sciences due to its spontaneous adhesion properties to the universal surface. The previous studies about polydopamine were mostly related to a liquid / solid interface. In this presentation, we report the polydopamine membranes formed self-organized on the air / liquid interface.
Polydopamine was formed by self-oxidation of the dopamine in alkaline solution (pH 8.9 Tris-HCl buffer). In order to induce the flattened solution drops, the 500 μL buffer solution containing 10 - 20 mg / mL-dopamine pours into a part of a 96 well plate. Membranes formed at the air / water droplets were scooped up to a Si substrate by Langumuir-Blodgett method. The thickness and the roughness were measured by atomic force microscope (AFM). The flattened solution drops were observed after about 60 minutes, and the height of flattened solution decreased with incubation time and wrinkles were observed at the top of the flattened water. The thickness of the membrane on the drop was about 9.1 nm. In order to reveal the role of the water evaporation, we performed the experiment at liquid/liquid interface. Parts of a 96 well plate filled with dopamine solution were relocated to glass cup filled hexane. Interestingly, the flattened water drops were not induced under the condition of the liquid/liquid interface after 50 minutes. However, reducing the volume of the water drop (80 μL), the flattened water drops were observed.
From these results, we suggest a following formation mechanism: 1. dopamine in the water drop were polymerized by air oxidization 2. polydopamine membrane were formed on the air/liquid or liquid/liquid interfaces 3. water drops were flattened with water evaporation or directorial extraction. These results indicate that the polydopamine membranes can overcome the surface pressure of the water drops enough to flatten the surface of solution. The self-organized membranes of polydopamine play a significant role on formation of this interfacial phenomenon and will be applicable to novel two-dimensional materials.
Polydopamine was formed by self-oxidation of the dopamine in alkaline solution (pH 8.9 Tris-HCl buffer). In order to induce the flattened solution drops, the 500 μL buffer solution containing 10 - 20 mg / mL-dopamine pours into a part of a 96 well plate. Membranes formed at the air / water droplets were scooped up to a Si substrate by Langumuir-Blodgett method. The thickness and the roughness were measured by atomic force microscope (AFM). The flattened solution drops were observed after about 60 minutes, and the height of flattened solution decreased with incubation time and wrinkles were observed at the top of the flattened water. The thickness of the membrane on the drop was about 9.1 nm. In order to reveal the role of the water evaporation, we performed the experiment at liquid/liquid interface. Parts of a 96 well plate filled with dopamine solution were relocated to glass cup filled hexane. Interestingly, the flattened water drops were not induced under the condition of the liquid/liquid interface after 50 minutes. However, reducing the volume of the water drop (80 μL), the flattened water drops were observed.
From these results, we suggest a following formation mechanism: 1. dopamine in the water drop were polymerized by air oxidization 2. polydopamine membrane were formed on the air/liquid or liquid/liquid interfaces 3. water drops were flattened with water evaporation or directorial extraction. These results indicate that the polydopamine membranes can overcome the surface pressure of the water drops enough to flatten the surface of solution. The self-organized membranes of polydopamine play a significant role on formation of this interfacial phenomenon and will be applicable to novel two-dimensional materials.