Synthesis and dispersion of colloidal silver nanoparticles on microcellular polyHIPE support

Highly open-cell polyHIPE solid foam was prepared by polymerization of continuous organic phase of a high internal phase emulsion (HIPE) containing styrene (St), acrylonitrile (AN), divinelybenzene (DVB), and Span 80 as emulsifier. The cross-linked SAN copolymer foam was reinforced by adding 1 and 3 wt% organoclay, i.e. Cloisite30B (C30B), into its emulsion organic phase in order to improve the compression properties of the resulting foam. Scanning electron micrographs indicated a typical highly open-cell structure of the neat and reinforced copolymer foams. The introduction of 1 wt% C30B inside the emulsion foam significantly decreased the weighted-average cell diameter from 62 to 16.1 μm, and the mean intercellular pore size from 17.9 to 4.2 μm. On the other hand, the above organoclay level considerably improved the crush strength of the foam by about 271%. The surface of the foams was then coated by colloidal silver nanoparticles (SNPs) previously generated by a reduction of silver ions (Ag+) using sodium borohydride (NaBH4) as the reducing agent and polyvinyl alcohol (PVA) as the stabilizing agent. The colloidal SNPs were characterized by ultraviolet–visible (UV) spectroscopy, dynamic laser light scattering, and X-ray diffraction (XRD) techniques. The effect of PVA molecular weight, reduction temperature, and foam organoclay level on the mean size and dispersion state of SNPs dispersed on polyHIPE support has been investigated. The results showed that the SNPs prepared using low-molecular PVA at higher reduction temperature dispersed well on the support surface. A more uniform SNP dispersion as singlet was observed for the copolymer foam reinforced by organoclay.

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► Colloidal silver nanoparticles (SNPs) were prepared in an aqueous media.
► The higher reduction temperature of silver cations decreased the particle size.
► The SNPs were coated on the surface of polyHIPE solid foams.
► The SNP prepared at the higher temperature are well dispersed on the foam surface.
► The presence of organoclay in the reinforced foam improved the SNP dispersion.