A facile method for the construction of stable polymer–inorganic nanoparticle composite multilayers

In this paper, we have developed a facile and general strategy to enhance the stability of multilayers incorporating nanoparticles and the weak polyelectrolyte poly(allylamine hydrochloride) (PAH). Using Fe3O4 nanoparticles (Fe3O4 NPs) and Au nanoparticles (Au NPs) as separate model systems, after multilayers of nanoparticles and PAH were constructed employing the layer-by-layer (LbL) technique, 4,4′-diazostilbene-2,2′-disulphonic acid disodium salt (DAS) was post-infiltrated into the multilayers and subsequent photochemical cross-linking was completed under UV irradiation. The stability of multilayers with Fe3O4 NPs and Au NPs were both improved significantly, and less than 15% of the nanoparticles were lost from the multilayers after an intensive agitation. The UV-visible spectroscopy and atomic force microscopy measurements supported the improvement of the stability of the multilayers.