Investigation of optical, film formation, and magnetic properties of PS latex/SP‐MNPs composites

In this work, the optical, film formation, morphological and the magnetic properties of a novel type of nanocomposite system, composed of polystyrene (PS) latex and core‐shell superparamagnetic nanoparticles (SP‐MNPs), is presented. The film formation and optical properties were examined by UV‐vis technique, morphological changes by scanning electron microscopy and magnetic properties studied using vibrating sample magnetometer (VSM) as a function of SP‐MNPs content. A series of mixtures were prepared by mixing of PS latex dispersion with different amount of SP‐MNPs in the range of (0–100 wt%). PS/SP‐MNPs films were then prepared from these mixtures on glass substrates using drop casting method. After drying, film was separately annealed at elevated temperatures between 100°C and 250°C. In order to monitor film formation process, transmittance of these composites was measured after each annealing step as a function of SP‐MNPs content. It was found that below a critical SP‐MNPs content, PS percolates into the SP‐MNPs hard phase and forms an interconnected network upon annealing. However, above this critical value, PS latexes were no longer film forming at all temperatures. Besides, composite films showed superparamagnetic behaviors. The saturation magnetization (M_s) first increased and reached to 0.014 emu/cm³ at 50 wt% SP‐MNPs, then decreased to 0.010 emu/cm³ with increasing SP‐MNPs content. The maximum value of M_s was approximately 0.020 emu/cm³ and was obtained for the 85 wt% SP‐MNPs content film. These results indicated that the optical, film formation and magnetic properties of PS/SP‐MNPs composite films can be readily tuned by varying SP‐MNPs content. POLYM. COMPOS., 40:1018–1033, 2019. © 2018 Society of Plastics Engineers