Abstract
A systematic study for the preparation and structural analysis of poly(styrene-co-acrylic acid) composite nanospheres (PSA) and silver nanoparticles loaded poly(styrene-co-acrylic acid) composite nanospheres (nAg@PSA) is reported. Poly(styrene-co-acrylic acid) nanospheres were synthesized by soap-free emulsion polymerization of styrene (St) and acrylic acid (AA) in water. Ag nanoparticles (Ag-NPs) were well-dispersed on the surfaces of poly(styrene-co-acrylic acid) composite nanospheres by in situ chemical reduction of AgNO3 using NaBH4 as a reducing agent in water. The particle size of PSA nanospheres was uniform. The surfaces of PSA nanospheres were distributed by highly uniform half-sphere arrays. Those half-sphere protruded more with the increase of the feeding amount of AA or the feed ratios of AA and St. The carboxyl groups content of nanospheres was directly proportional to the nanosphere surface area. This relationship and X-ray photoelectron spectroscopy and transmission electron microscopy images of the PSA nanospheres indicate that the acrylic acid was mainly distributed on the surface of the polystyrene spheres with unnegligible thickness. The number of Ag-NPs depends on immobilized carboxyl groups on the surface of PSA, according to thermogravimetry, ultraviolet-visible, X-ray diffraction and transmission electron microscopy results.
Highlights
Composite microspheres consisting of dielectric polymer core and metallic shells have become a subject of intense interest in various fields during past decades
The crystalline structures of silver particles supported on the poly(styrene-co-acrylic acid) composite nanospheres (PSA) nanosphere surface were characterized by X-ray diffraction (XRD; PANalytical X’pert Pro, PANalytical Co., Almelo, The Netherlands) and the XRD data was collected in a 2θ range of 30–80◦ at a scan rate of 4◦/min
Ultraviolet-visible (UV-vis; Shimadzu UV-2550, Shimadzu, Kyoto, Japan) spectroscopy was employed for qualitative characterization of the optical properties of silver nanoparticles supported on poly(styrene-co-acrylic acid) composite nanospheres
Summary
Composite microspheres consisting of dielectric polymer core and metallic shells have become a subject of intense interest in various fields during past decades. By variation of the shell thickness and the core radius it is possible to adjust the plasmon resonance of the metallic shell particles over the whole visible and infrared region of the spectrum [5] Because of their monodispersity and tunable optical properties, these microspheres may be used as building blocks for various applications such as for metallodielectric photonic crystals. An in situ reduction deposition method has been reported Because this method for preparing dielectric core/metallic shell composite materials is simple, reproducible and well-controlled, it has attracted much attention and is widely used in the preparation of core-shell structure composite microspheres. This work may rise wide interest on structure and composition controllable preparation of core-shell structure microsphere for application in catalysis, antibacterial, substrate materials for surface enhanced Raman spectroscopy, and so on
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