Abstract
We have tried to prepare the microcapsules containing water droplets stabilized with solid powder by utilizing the (W/O)/W emulsion. The water droplets as core material were stabilized in the monomer droplets with titanium dioxide (TiO2) as a particulate surfactant. Before adding the TiO2 powder into the monomer phase, the powder was modified with triethoxyvinylsilane to adjust the degree of hydrophobicity and to promote adhesion on the interface between the inner water phase and the monomer phase in the (W/O) emulsion. It was investigated how the degree of hydrophobicity of the TiO2 powder affected the stability of water droplets in the (W/O) emulsion and the (W/O) droplets in the (W/O)/W emulsion. Moreover, the microcapsule diameters were measured before and after the expansion operation where the water droplets microencapsulated were applied as a blowing agent. The expansion ratio was increased with increase in the stability of the water droplets and the amount of water microencapsulated.
Highlights
Microcapsules containing water as a core material have been applied in the various fields such as pharmacy, adhesives, agricultural medicine, cosmetics, food and so on, because water is able to dissolve various materials of inorganic and organic substances [1,2]
According to this stabilizing mechanism of solid powder, it was tried to investigate with the preliminary test whether the stabilizing effect of the TiO2 powder modified in the (W/O)/W emulsion was observed or not
First the (W/O) emulsion was formed by adding the TiO2 powder, water and oil soluble surfactant into the monomer mixture and agitating with homogenizer
Summary
Microcapsules containing water as a core material have been applied in the various fields such as pharmacy, adhesives, agricultural medicine, cosmetics, food and so on, because water is able to dissolve various materials of inorganic and organic substances [1,2]. With the suspension polymerization method, it is important to form the stable (W/O) dispersion, where the water phase (W) is the core material and the oil phase (O) is the polymerizable monomer. For this purpose, the oil soluble surfactant species have been inevitably added and higher mechanical energy has been loaded. There are few reports which have investigated the effect of solid powder on the stability of water droplets in the (W/O) emulsion and prepared the microcapsules containing water as a core material. The purposes of this study are to investigate the stabilizing effect for the (W/O) and the (W/O)/W emulsion with the TiO2 powder modified by the coupling agent, to prepare the microcapsules containing water and to apply the microencapsulated water as a blowing agent for the preparation of expanded polystyrene
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