Size-dependent filtration of nanoparticles on porous films composed by polystyrene microsphere monolayers and applications in site-selective deposition of nanoparticles
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Composite films composed of polystyrene (PS) microsphere monolayers and gold (Au) and/or silver (Ag) nanoparticles (NPs) decorations were prepared by a novel size-dependent filtration effect on close-packed PS microsphere arrays. The uniform pores inlaid in the PS monolayer films acted as the transport tunnels for NPs. The steric restriction induced by the size of the pores was used as a main strategy to fabricate hybrid micro/nano films, which were composed of PS microspheres with inhomogeneous anisotropic decorations. The Au and Ag NPs were used as the building blocks to decorate the PS microspheres through a layer-by-layer self-assembly technique with the aid of polyelectrolyte coupling agents. Only the small particles which could pass through the micropores could reach to and deposit on the inner surfaces of the PS microsphere monolayer films. Large particles remained on the outside and could only deposit on the outer surfaces. Thus, the inhomogeneous anisotropic decoration was obtained. This study provides a novel strategy for fabricating anisotropic micro/nanostructures by the size-dependent filtration effect of NPs on porous films and has the potential in applications of anisotropic self-assembly, sensor, and surface modifications at nanoscale.
KeywordsPolystyrene microsphere Porous Size-dependent Nanoparticle Nanofabrication
The authors greatly acknowledge the financial support from the Natural Science Foundation of China (Grant Nos. 21103062, 21273091, 21221063, 21327803, 41472024, and 21411140235), the 111 project (B06009), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20100061120087 and 20110061110017), and the Development Program of the Science and Technology of Jilin Province (20130508). W. D. R. is also grateful to the Postdoctoral Science Foundation of China (Grant No. 2014M561286), Special Funds of State Key Laboratories, Seeding Money Project of Jilin University, and R & D start-up funds of Jilin University.