مشخصات پژوهش

In this work, we have demonstrated the fabrication of 2D binary colloidal crystals consisting of monodisperse polymethyl methacrylate (PMMA) microspheres with diameters of 1135, 723 nm and polystyrene (PS) microspheres with diameters of 190 nm. To do this, the co-self-assembly method at the air-water interface was used. Several parameters affect the quality of these 2D binary colloidal crystals such as size ratios, concentrations of small and large particles, dispersion environment, etc. Here, a colloidal suspension of large PMMA and small PS spheres mixed with ethanol solvent is slowly injected onto a glass substrate inserted in a petri dish. Then, the colloidal spheres are rapidly spread on the water surface. A monolayer of PMMA and PS microspheres forms on the water surface. These 2D binary colloidal crystals can be transferred as a whole onto any other substrates. A challenging issue in fabricating 2D binary colloidal crystals is the penetration of PS spheres into the empty spaces between large polymer microspheres. It has been shown in this work that adjusting the diameters of the spheres of the two colloids is crucial in the formation of 2D binary colloidal crystals. It was concluded that the 190 nm PS microspheres could penetrate into the free space between the 723 nm PMMA microspheres much better than the 1135 nm ones. 2D binary colloidal crystals can have a wide range of applications in various fields, including the fabrication of photonic devices, biosensors/chemical sensors, chromatography, biomedical devices, and cell culture tools.