Study On Influencing Factors Of W/O/W Multiple Emulsions Formed By One-step Emulsification

Multiple emulsions,as a kind of special structure of emulsion,are composite systems in which O/W and W/O emulsions coexist as dispersed droplets.Because the double-membrane structure of multiple emulsions may help encapsulate active ingredients,which are not only hydrophilic but also hydrophobic substance,these species are widely used in cosmetics.In this paper,the influence of the preparation process on formation of W/O/W multiple structure were studied first.Results showed that there is a high water content in the multi-structure emulsion prepared by one-step method.The best the optimum emulsification temperature is 80? and the homogeneity rate is 15500rpm;Water added rate does not affect the transformation of the system.After that,the influences of formulation composition on formation of W/O/W multiple emulsion were studied.The experimental results show that hydrophilic emulsifiers with large HLB and P>1 or with long branched alkyl groups and polyethers can form multiple emulsions.For hydrophobic emulsifiers,firstly,the emulsifier with small HLB and P<1/3,or with long branched alkyl groups and polyethers can help to form multiple emulsions.Secondly,hydrophobic emulsifiers with the help of structural similarity and the intermolecular bonding via van der Waals forces between hydrophobic emulsifiers and oil,could form a strong W/O interface.Thirdly,hydrophobic emulsifiers with good solubility in oils are also conducive to the formation of one-step multiple emulsions.It is not conducive to the formation of multiple structures with the addition of thicker.At last,the influences of formulation composition on pseudo-ternary phase diagram of one-step W/O/W emulsion were studied.The structure of the emulsifier,the oil polarity,the polyols with different carbon chain length and inorganic salt,all these factors can effect the pseudo-ternary phase diagram of multiple system.The results demonstrated that the structure of emulsifier has the greatest influence on the pseudo-ternary phase diagram.The larger the HLB of mixture emulsifiers,the larger the O/W area formed.The smaller the polarity of oil,the more beneficial to form the multi-structure.The addition of glycerol can increases the W/O/W area while with the reduction of polyol hydroxyl and the growth of the carbon chain,the W/O/W area are decreased.The inorganic salt can also make the W/O/W area reduced.