Effect of the ratio between hydrophobic mesoporous silica (Aerosil^®R812S) and water on the formation and physical stability of water-entrapped self-assembly particle

Abstract

Potential effect of the proportionality between Aerosil^®R812S over the water on the formation of water entrapped self-assembly core-shell structure is the main aim of this studies. Self-assembly hydrophobic silica particle (SAHS) containing water was fabricated by abruptly incorporation of water into R812S. Five different weight percent of R812S were investigated in terms of the ability to form SAHS including their physical stability. The lowest ratio of 1% was not able to form SAHS. More than 2 up to 5% of R812S yielded core-shell structure of SAHS in the dry solid form. The smaller size of SAHS would be the result of higher level of R812S used. The finer the water droplet the more consume the silica particle used in order to gain stable SAHS. In terms of stability, they disclosed unacceptable qualities at 6 months of storage due to either remarkable phase separation or squeezing out of inner water core. It should be due to the thermodynamic driven forces that accelerated the movement of both water and silica shell to coalesce. In conclusion, the stable SAHS comprised of sufficient amount of R812S (more than 2% by weight) with water. It could be kept within short term period with acceptable properties.

Keywords:

• Hydrophobic mesoporous silica
• water
• self-assembly
• core-shell structure
• physical stability

Acknowledgements

The authors would like to thank the Research Instrument Center of the Faculty of Pharmaceutical Sciences, Chulalongkorn University, for providing research instruments. In addition, the graphical objects were kindly prepared by Mr. Chayapol Tungphatong.

Additional information

Funding

This work was financially supported by the Master of Science Program in Cosmetic Science, Faculty of Pharmaceutical Sciences, Chulalongkorn University.