Abstract
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.
Highlights
Stimuli-responsive microcapsules for controlled release of core material have been applied in many fields such as drug delivery systems (DDS), painting, self-healing agent, cosmetics, foods [1-9]
The microcapsules become irregular and the surface becomes slightly rough at CMC = 1.0 and 1.5 wt%
This is considered due to increase in the degree of shrinkage of polymeric chain with the methyl cellulose (MC) concentration
Summary
Stimuli-responsive microcapsules for controlled release of core material have been applied in many fields such as drug delivery systems (DDS), painting, self-healing agent, cosmetics, foods [1-9]. The stimuli responsive microcapsules have been mainly prepared with the chemical methods such as the miniemulsion polymerization method, the suspension polymerization method, the interfacial reaction method and the physical chemistry methods such as the dryingin-liquid method, the coacervation method, the heterocoagulation method and the spray drying method [10] Among these preparation methods, the preparation method without the continuous water phase is desired to microencapsulate the water soluble core materials, because the core materials are easy to dissolve in the water phase during the microencapsulation process. The purposes of this study are to investigate whether the microcapsules with the temperature and the water responsibility are able to be prepared with the spray drying method or not and how the release of hydroquinone is controlled by stimuli of temperature and water
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