(608c) Preparation of Core-Shell Nano-Particles In Emulsifier-Free Emulsion Polymerization and Monitoring with Spectroscopy Raman along the Reaction

Emulsifier-free emulsion polymerisation is of both industrial and academic interest since the resulting polymer latex is free from absorbed surfactant and could contain highly monodisperse polymer particles. This technique is studied for preparation of core-shell nano-particles of Polystyrene and Poly(methyl methacrylate) because depending on the polymerization parameters and conditions, the reaction can selectively yield a variety of particles with different morphologies. The synthesis of core-shell latexes usually does not lead to an ideal core-shell morphology with a complete phase separation, giving rise to possible substructures of such core-shell latexes with different interfaces. These interfaces consist of mixed phases which are composed of the core and the shell component. Depending on the compatibility of the two polymers and the reaction conditions, the components in the interface can be mixed on a molecular level with a continuous concentration gradient or microdomains can be formed. The morphology of the entire particle and the interface between the two components in core-shell polymers can sensitively change the macroscopic properties of materials over a wide range. Therefore, the investigation of the particle morphology is an important task for further applications of core-shell systems such as paints, adhesives, coatings, or impact resistant plastics. In this work core and shell were prepared at different composition ratios. The latex core was synthesized by batch emulsion polymerization and the latex shell through semi-continuous sequential emulsion polymerization. Both latex were characterized by using transmission electron microscopy (TEM), particle size analyzer, differential scanning calorimetry (DSC) and the reaction is monitoring with spectroscopy Raman. The main this monitoring is related some variables of the process with spectrums generated in the monitoring of the reaction. In this way were studied the rate of polymerization, monomer concentration residual, polymer concentration formed. The results show this technique like a tool becomes interesting to understanding the system of emulsifier-free emulsion polymerization for prepare core-shell particles.