Synthesis and magnetic properties of organic multilayer films based on the layer-by-layer assembly

Two polymers containing pyridine rings were prepared by free-radical polymerization and confirmed by Fourier transform infrared and 1H NMR spectra. The preparation of four multilayer films that were obtained by self-assembly of the polymer and the transition metal neutralized polyelectrolyte on PE substrate was described. UV–vis spectra and atomic force microscopy images were applied to characterize these films and indicate the uniform assembling process. The driving force for building up the multilayer films was identified by infrared spectroscopy to be the coordination interaction. The magnetic behavior was examined as a function of magnetic field strength at 30 kOe and as a function of temperature (5–300 K). All films display strong soft ferromagnetic properties and higher than those of the bulk materials. The magnetic results show that the layer-by-layer self-assembling approach is beneficial to the ordered alignment of adjacent paramagnetic spins and induces better magnetic phenomena. Copyright © 2015 John Wiley & Sons, Ltd.