Effect of dispersant on encapsulated phthalocyanine/polymer nanoparticles via mini-emulsion polymerization

In this study, phthalocyanine green pigment encapsulated polymer particles were prepared by mini-emulsion polymerization method and the particle size and color change according to the ratio of pigment and dispersant were examined. Triton X-100 dispersant was used to disperse the phthalocyanine green pigment, and the characteristics of the dispersibility and stability were evaluated while adjusting the concentration of the dispersant to 0,0.2, 0.4, and 0.8% (w/v) in the pigment dispersion. As the concentration of Triton X-100 increased, the dispersibility of the pigment was clearly improved. Without Triton X-100 dispersant, the spherical particles with diameters of 3-4 urn and 200-300 nm were polymerized at the same time due to the mini-emulsion instability. However, when dispersant was added, pigments were successfully dispersed and the mini-emulsion was well stabilized. As a result, phthalocyanine green encapsulated polymer particles which had the spherical shape with diameter of 200-300 nm were uniformly polymerized. The effect of the dispersant concentration was directly related to the mini emulsion stability and the pigment encapsulation efficiency. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to characterize the morphology and particle size distribution of the polymerized particles, and Fouriertransform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA) and ultraviolet-visible spectroscopy (UV-Vis) were used to evaluate the characteristics of encapsulation efficiency. As a result, it was confirmed that the highest encapsulation efficiency was obtained when 0.4% (w/v) of Triton X-100 was used.