A new route of emulsifier-free emulsion polymerization based on the homogenous mechanism was investigated to prepare magnetic nanoparticles coated by poly (methyl methacrylate) (PMMA). The experimental results confirm the formation of PMMA thin and unique layers covering magnetite cores. The polymer layer thickness, determined from transmission electron microscopy (TEM) images, increases from 4.3 nm to 6.8 nm with increasing mass ratio of MMA to magnetite from 3:1 to 11:1. The increase of the polymer thickness results in the decrease in magnetization saturation of polymeric coated magnetic particles. However, this reduction, no more than 13 emu g −1 , is much lower compared to that in other studies with the presence of surfactants or emulsifiers. Besides, the dispersion stability of the prepared particles is significantly improved.

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In this study, the optimization of flexographic water-based ink formulation was carried out. The aim is to minimize the contact angle of the ink on polymer substrates. A factorial design was used to evaluate the effects and interactions of three factors, which are dispersant, wetting agent and antifoam concentration on the wettability of ink. The optimal conditions obtained from the desirable response are dispersant of 9.65%, wetting agent of 0.58% and antifoam of 0.55 %. Under these conditions, about 15O of contact angle is obtained. The validity of the statistical experimental strategies was verified by the ink samples prepared under the optimized conditions.

In this study, the performance of a new triarylsulfonium photoinitiator in the initiation of cationic polymerization of vinyl monomers was investigated by infrared spectroscopy (IR). The effect of the emission spectrum of light sources on the kinetics of the curing process was examined. The results indicate that the light source characterized by a total overlap of its emission spectrum with the photoinitiator absorption spectrum is the best system for effective cure. In the case of smaller overlap of spectrums, the conversion degree and the rate are lower. Nevertheless, it is easy to regulate by extending the energy of the emitted light. At the UVB light source, the maximal conversion degree is 71.8%, with the polymerization rate of 1.68 s-1, which is faster than the corresponding free-radical photopolymerization of acrylic monomers.

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