Preparation of Microcapsules with Liquid Droplet Coalescence Method Followed by Phase Separation

Novel preparation method of microencapsules was developed on the basis of the liquid coalescence method followed by phase separation. Oil droplets of limonene dissolving expanded polystyrene as a shell material were forced to collide and coalesce with the Isopar oil droplets of core material in the continuous wates phase. When two kinds of oil droplets are collided and coalesced with each other, expanded polystyrene dissolved in the limonene oil may be phase-separated in the oil droplets newly formed to form the microcapsule shell, because the Isopar oil was a poor solvent for expanded polystyrene but a good solvent for the limonene oil. In the experiment, the diameter (or number) of limonene oil droplets dissolving expanded polystyrene was mainly changed, because the coalescence frequency between the droplets is strongly dependent on the number of droplets. Favorable core shell types of microcapsules with the shell thickness from 1.0 to 5.0 μm were able to be prepared under all the experimental conditions adopted here.

Preparation of Microcapsules Containing Water Droplets Stabilized with Solid Powder and Application to Blowing Agent

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.

Preparation of Microcapsules Containing Phase Change Material and Silicon Carbide Powder with Interfacial Polycondensation Reaction Method

The fundamental experiments were performed to establish the operational conditions required to prepare the microcapsules containing paraffin wax as a phase change material (PCM) and SiC powder with the interfacial polycondensation reaction. It was investigated how SiC powder affected a few characteristics of microcapsules such as the diameters of microcapsules, latent heat storage density, thermal responsibility and supercooling. In the experiment, the concentration of oil soluble surfactant, the revolution speed of impeller for preparing the (O/W) emulsion and the added weight of SiC powder were changed stepwise. The microcapsules containing PCM in which SiC powder was dispersed could be prepared well and characterized. The diameters of microcapsules increased by containing SiC powder and the content of SiC powder could be increased by performing surface modification of SiC powder. Latent heat storage density decreased with the content of SiC powder. Supercooling of PCM and thermal responsibility could be improved to some degree by containing SiC powder.

Preparation of Microcapsules Containing Camellia Oil with Heterocoagulation between Chitosan and Oleic Acid

It was tried to microencapsulate camellia oil using heterocoagulation between fatty acid dissolved in camellia oil and chitosan dissolved in the continuous water phase. Oleic acid as a fatty acid was dissolved in camellia oil in order to certainly form the microcapsule shell made from oleic acid and chitosan. The microcapsules were observed with optical microscope and characterized about the diameters, ζ-potential, FTIR analysis and adhesion feature on human hair. Microcapsules with the mean diameter in the range from ca. 1.5 μm to 4.5 μm could be prepared with the preparation method presented in this study. The oil droplets of camellia oil charged negatively to be -54.6 mV and the microcapsules charged positively to be 59.6 mV. The microcapsules adhered well on the negatively charged human hair and were kept stably before and after drying at room temperature for 24 h and blowing.

Development of Preparation Method for Microencapsulating Uycalyptus Oil Containing Fine Aqueous Droplets by Use of Interfacial Condensation Reaction between Hydroxy Propyl Methyl Cellulose and Tannic Acid

It was tried to develop the preparation method for microencapsulating the uycalyptus oil containing fine aqueous droplets by using the interfacial condensation reaction between hydroxyl propyl methyl cellulose and tannic acid. Uycalyptus oil containing fine aqueous droplets was dispersed in the continuous water phase to form the (W/O)/W emulsion. Tannic acid and hydroxyl propyl methyl cellulose were dissolved in the inner aqueous droplets and in the outer continuous water phase, respectively. Tannic acid transferred through the oil phase from the inner water droplets to the interface between the oil phase and the continuous water phase and then, reacted with hydroxyl propyl methyl cellulose. In the experiment, the concentrations of hydroxyl propyl methyl cellulose and tannic acid were mainly changed stepwise. The uycalyptus oil containing the fine water droplets could be microencapsulated satisfactorily. It was found that the microcapsules were composed of the gelated hydroxyl propyl methyl cellulose film as the shell, the fine aqueous droplets as the first core and the oil droplet as the second core.

Preparation of Microcapsules Containing Erythritol with Interfacial Polycondensation Reaction by Using the (W/O) Emulsion

It was tried to microencapsulate erythritol as a phase change material with the interfacial polycondensation reaction method by using the (W/O) emulsion and to characterize the microcapsules prepared. In the experiment, toluene diisocyanate, diphenyl methane diisocyanate and hexamethylenediisocyanate were used to form the polyurethane shell and the effects of them on the heat storage density and the microencapsulation efficiency were investigated. Furthermore, the effect of supercooling prevention agent on the phase change behavior of erythritol was investigated. The microcapsules prepared with toluendiisocyanate monomer showed the highest heat storage density and the higher microencapsulation efficiency. Considerable supercooling phenomenon in the microcapsule was observed and prevented to a certain degree by addition of potassium dihydrogen phosphate and calcium sulfate as the supercooling prevention agent.

Preparation of Thermosensitive Microcapsules Containing Water Soluble Powder by Melting Dispersion Cooling Method

It was tried to prepare the thermosensitive microcapsules containing the water soluble solid powder by the melting dispersion cooling method and to establish the optimum preparation conditions. As a model water soluble solid powder, sodium hydrogen carbonate was adopted in order to generate carbon dioxide gas and as a thermosensitive shell material, olefin resin with the melting point of ca. 40°C was used. In the experiment, the concentration of olefin resin in the shell material solution was mainly changed together with the concentrations of the oil soluble surfactant species and the α-tocopherol as a modifier of shell. Addition of α-tocopherol into the shell material solution could prevent the core from breaking away during the microencapsulation process and result in the higher microencapsulation efficiency, because the dispersion stability of solid powder in the shell material solution could be increased due to the increase in affinity between the shell material solution and solid powder. Also, the microencapsulation efficiency increased with the concentration of olefin resin, became maximum at 50 wt% and then, decreased. The microcapsules were found to begin melting at 36°C and to generate carbon dioxide gas.

Preparation of Microcapsules Containing Dye Aqueous Solution and Investigation of Release Feature According to Preparation Method

Microcapsules containing the dye aqueous solution were prepared with three kinds of preparation methods and the release feature of microcapsules with each preparation method was mainly investigated. As a dye tried to microencapsulate, methylene blue was adopted, because methylene blue aqueous solution was changed in color with light irradiation and utilized in order to check the degree of river pollution. Microencapsulation using multiple emulsion was performed with the suspension polymerization method, the inverse interfacial polycondensation method and the suspension polymerization in parallel with the interfacial polymerization method, respectively. The release feature of microcapsules prepared with each preparation method was estimated with the solute permeability coefficient. It was found that the release feature of dye aqueous solution was different according to the preparation method and could be delicately controlled by microencapsulating with the suspension polymerization in parallel with interfacial polycondensation reaction and forming the polyurethane shell on the surface of the dye aqueous solution droplets.

Preparation of Microcapsules Containing Grape Polyphenol with the Spray Drying Method Followed by the Layer-by-Layer Method

It was tried to prepare the microcapsules containing grape polyphenol with the spray drying method followed by the layer-by-layer method. As grape polyphenol was water soluble, the spray drying method was adopted to obtain the higher content. As the shell material of the first microcapsules prepared by the spray drying method, palmitic acid with the melting point of 60&degC was adopted in order to prevent grape polyphenol from dissolution into water. As the shell material of the second microcapsules prepared by the layer-by-layer method, chitosan was used to coat the first microcapsules and to give the microcapsules alcohol resistance. In the experiment, the spray drying conditions such as the inlet temperature and the spraying pressure, the oil soluble surfactant species and the chitosan concentration were changed. The mean diameters of microcapsules could be controlled in the range from 5 μm to 35 μm by changing the spraying pressure and the inlet temperature. The yield of microcapsules and the microencapsulation efficiency over 50% could be obtained under the conditions of P = 1.0 kgf/cm2 and Tin = 100&degC. Furthermore, the microencapsulation efficiency could be increased by adding the oil soluble surfactant with the larger HLB value. Coating with chitosan could considerably increase alcohol resistance.

Preparation of Microcapsules Containing Artificial Diet for Tropical Fishes with Spray Gelling Method

The microcapsules containing the artificial diet for tropical fishes were prepared with the spray gelling method in order to prevent water environmental pollution. The carboxymethyl cellulose sodium aqueous solution, in which α-tocopherol droplets containing the powdery artificial diet were dispersed, was dropped or sprayed into the chitosan aqueous solution. Microcapsules were prepared by forming polyionic complex shell made from chitosan and carboxymethyl cellulose sodium. In the experiment, the concentration of carboxymethyl cellulose sodium (CMCNa) was mainly changed to investigate the effect on the diameters of microcapsules, the content and the microencapsulation efficiency. The microcapsules couldn’t be prepared with the concentration of carboxymethyl cellulose sodium less than 3.0 wt%. The microcapsules were the core-shell type. The diameters of microcapsules were increased with the concentration of CMCNa and the microencapsulation efficiency of ca. 100% could be obtained by the preparation method presented in this study. The microcapsules were found to be eaten well by tropical fishes and to prevent water environmental pollution.

Preparation of Microcapsules Containing Triple Core Materials with Interfacial Condensation Reaction

In this manuscript, we describe the novel method for preparing the microcapsules containing α-tocopherol oil droplets as the first core material, calcium chloride powder as the second core material and the fine water droplets as the third core material by the interfacial condensation reaction between hydroxyl propyl methyl cellulose and tannic acid. The interfacial condensation reaction was performed between hydroxyl propyl methyl cellulose dissolved in the continuous water phase and tannic acid dissolved in the inner fine water droplets as the third core material. The calcium chloride powder as the second core material was dispersed in the α-tocopherol oil droplet as the first core material beforehand. The α-tocopherol oil containing the second and the third core materials was dispersed in the continuous water phase to form the [(S + W)/O/W] emulsion. The α-tocopherol oil as the first core material was microencapsulated satisfactorily and the contents of the second core material were increased with the concentration of stearic acid as the oil soluble stabilizer. The mechanical strength of microcapsules increased with the concentration of hydroxyl propyl methyl cellulose. Thermal energy could be released by breaking the microcapsules in water and by dissolving calcium chloride in the continuous water phase.

Preparation of Polymer Composite Particles by Phase Separation Followed by Suspension Polymerization

The novel method for preparing the polymer composite particles has been developed. It was tried to prepare polymer composite particles composed of polystyrene and carbon black with the phase separation method followed by suspension polymerization. In order to prepare the polymer composite particles with the more uniform diameter, the styrene monomer droplets containing carbon black were formed with phase separation emulsification in which ethyl alcohol and water were used as the good solvent and the poor solvent for styrene monomer, respectively. In the experiment, the surfactant species and their concentrations, the pouring velocity of water and the weight ratio of carbon black to styrene monomer were mainly changed. Water was poured at the given pouring velocity into ethyl alcohol in which styrene monomer and an initiator were dissolved and carbon black was dispersed beforehand. The spherical polymer composite particles containing carbon black were prepared with Tween 20 and Tween 80 of nonionic surfactants and the irregular polymer composite particles were prepared with PVA, SDS and Kotamine. The diameters of polymer composite particles increased with the pouring velocity of water and with the weight ratio of carbon black to styrene monomer.

Microencapsulation of Sodium Hydrogen Carbonate to Generate Carbon Dioxide with Thermal Responsible Shell Material

This paper tried to develop the optimum procedure for microencapsulating water soluble solid powder with the thermal responsible material by the melting dispersion cooling method. Sodium hydrogen carbonate was adopted as a water soluble solid powder instead of microencapsulating carbon dioxide gas. The shell material was composed of olefin wax and α-tocopherol. In the experiment, the concentration of oil soluble surfactant and the water soluble surfactant species were changed. Sodium hydrogen carbonate was treated in the aqueous solution dissolving the water soluble surfactant to form the finer sodium hydrogen carbonate powder and to increase the content. The microencapsulation efficiency could be increased with the concentration of oil soluble surfactant and considerably increased by treating sodium hydrogen carbonate with the water soluble surfactant. Sodium hydrogen carbonate was protected well from environmental water. The microcapsules showed the thermal responsibility to generate carbon dioxide.

Effect of Polysaccharide Species on Storage Stability of Alginate Capsules Containing <i>α</i>-Tocopherol

Alginate capsules containing α-tocopherol were prepared adding polysaccharide species such as κ-carrageenan, gellan gum, pectin, curdlan and ghatti gum. The effects of polysaccharide species and the diameters of α-tocopherol on storage stability of the capsules were investigated and characterized in detail. As the contact angle of α-tocopherol to the capsule shell strongly affected storage stability, the contact angle was measured on the model sheet made of calcium alginate with polysaccharide species. The leakage ratio decreased with the contact angle and increased with the diameter of α-tocopherol. The capsules made of calcium alginate with gellan gum showed the largest contact angle and the highest storage stability. The capsules made of calcium alginate with curdlan, ghatti gum and pectin were harder than other capsules and showed higher storage stability. All the capsules showed the almost similar swelling ratio in the acidic solution with pH 4, but showed the different swelling ratios according to the polysaccharide species in the alkali solution with pH 9. The tablets were prepared with the wet and the dried capsules. The tablets prepared with the dried capsules showed higher storage stability.

Preparation of Microcapsules Containing Aqueous Solution of Azur B with Melting Dispersion Cooling Method and Application to DNA Amplification Detector

Microcapsules containing the aqueous solution of Azur B of a water soluble dye were prepared with the melting dispersion cooling method and applied to the amplification detector of plant DNA. Paraffin wax with melting temperature of 75°C was used as the shell material. In the experiment, the aqueous solution (W) of Azur B as the core material was dispersed in the melted paraffin wax (O) to form the (W/O) emulsion and then, the (W/O) emulsion was dispersed in the silicon oil (O’) as the continuous phase to form the (W/O)/O’ emulsion at 85°C. After formation of the (W/O)/O’ emulsion, the microcapsules were prepared by cooling the (W/O)/O’ emulsion to 50°C. The microcapsules were prepared by changing the concentration of oil soluble surfactant in the (W/O) emulsion and the volume of the (W/O) emulsion in the (W/O)/O’ emulsion. The microencapsulation efficiency increased with the concentration of oil soluble surfactant and finally became 100% under the optimum conditions. Furthermore, the microcapsules were melted down at temperature of 85°C to reveal the sharp thermal responsibility and to release the aqueous solution of Azur B. As a result, it was found that the microcapsules were able to be applied to the amplification detector of plant DNA by utilizing the reaction between DNA and Azur B.

Preparation of Porous Silicone Resin Sheet with Phase Inversion in Parallel with Non Solvent Induced Phase Separation and Application to Hollow Particle Formation

We have tried to prepare the porous silicone resin sheet with the phase inversion method in parallel with the non solvent induced phase separation method. In the experiment, ethyl acetate and water were adopted as a good solvent and a poor solvent for silicone resin, respectively and ethyl alcohol as an amphiphilic solvent was used to increase the solubility of ethyl acetate in water and decrease the interfacial tension by mass transfer from water to ethyl acetate. The concentration of silicone resin in ethyl acetate and the oil soluble surfactant species were changed. Increasing the concentration of silicone resin could depress coalescence between the water droplets in the (W/O) dispersion and increase the porosity and pore number density of silicone resin sheet. Span 80 among the oil soluble surfactant species made the porosity and pore number density larger. The effect of physical proparties of liquids concerned on the porosity and pore number density was discussed on the basis of dispersing behavior of liquid droplets in the liquid-liquid dispersion. The hollow silicone resin particles could be prepared by applying the preparation method presented here.

Preparation of Microcapsules Containing Water and Effect of Water Content on Expansion Behavior

The research work was conducted in order to establish the optimum conditions for preparing the expanded polystyrene beads without harmful substances and was aimed at the preparation of the microcapsules containing water and investigation of the effect of the water content on the expansion behavior of microcapsules. Microcapsules were prepared with the suspension polymerization method and the suspension polymerization in parallel with interfacial polycondensation method using the multiple emulsion (W/O)/W and adding a few additives. With increasing the crosslinking agent concentration in the suspension polymerization method, the water content increased from R = 5.8 wt% (CT = 0) to R = 8.2 wt% (CT = 4 wt%) and then, decreased to R = 7.5 wt% (CT = 9.0 wt%), while the expansion ratio increased from E = 1.01 (CT = 0) to E = 2.20 (CT = 4 wt%) and then, decreased to E = 1.01 (CT = 7.0 wt%). With increasing the added amount of wax in the suspension polymerization method, the water content gradually increased from R = 2.5 wt% to R = 8.0 wt%, while the expansion ratio increased from E = 1.01 to E = 1.5 and then, decreased. The water content and the expansion ratio could be increased by conducting suspension polymerization in parallel with interfacial polycondensation reaction from R = 5.0 wt % to R = 8.0 wt % and from E = 1.01 to E = 1.3, respectively. The maximum expansion ratio of E = 2.58 in this work was obtained under the conditions of crosslinking agent concentration of CT = 4.0 wt %, the added amount of wax of 3.0 g, addition of Agarose and the expansion temperature of T = 150°C.

Preparation of Composite Particles by Forming Pickering Emulsion Followed by Drying-In-Liquid and Effect of Stepwise Addition of Solid Powder on Structure of Composite Particles

It was tried to prepare composite particles made of polymer and two kinds of solid powders by forming Pickeringemulsion followed by the drying-in-liquid method and to investigate how the stepwise addition of solid powders affected the contained ratio and adhesion ratio of solid powders and the structure of composite particles. Limonene oil dissolving expanded polystyrene and ethylene glycol were adopted as the dispersed phase and the continuous phase, respectively. Magnetite and titanium dioxide were used as solid powders. Magnetite was added before or after formation of the (O/W) dispersion. Titanium dioxide was added at the various elapsed times from addition of magnetite. Titanium dioxide adhered only on the surface of composite particles irrespective of addition time. At the earlier addition of both solid powders, the surface-covering type composite particles were prepared. At the latter addition of titanium dioxide, a part of magnetite adhered on the surface and the remainder was dispersed into composite particle.

Preparation of Temperature and Water Responsive Microcapsules Containing Hydroquinone with Spray Drying Method

It was tried to prepare temperature and water responsive microcapsules containing hydroquinone as a water soluble core material with the spray drying method. Microcapsules were composed of ethyl cellulose (EC), methyl cellulose (MC) and P-N-isopropylacrylamid (PNIPAM). P-N-isopropylacrylamid and methyl cellulose were used as a temperature responsive polymer and as a water responsive polymer, respectively. Ethyl cellulose was the main shell material of microcapsule. At the microencapsulation process, the core and shell materials were dissolved in ethyl alcohol dissolving water (20 wt%) and then, spray-dried to prepare microcapsules. In the fundamental operation, the concentration and molecular weight of methyl cellulose were mainly changed. The releasing rate of hydroquinone was repressed at 40°C and increased at 20°C due to temperature responsive PNIPAM. Furthermore, responsibility to water was increased with the concentration of methyl cellulose.

Microencapsulation of Ascorbic Acid with Tripalmitin by Using Dry Coating Method

It was tried to microencapsulate the ascorbic acid powder as a redox initiator with tripalmitin by use of the dry coating method. In the experiment, the feed ratio of the amount of tripalmitin to that of ascorbic acid, the coating time and the concentration of ethyl alcohol of pulverizing solvent were changed stepwise. The characteristics of microcapsules such as the content of core material, the yield, the water proof degree, the microencapsulation efficiency and the mean diameter were estimated. The yield, the microencapsulation efficiency and the water proof degree gradually increased with the feed ratio, the coating time and the concentration of pulverizing solvent. The microcapsules showed the thermal responsibility and induced polymerization of methyl methacrylate monomer.