Multiple emulsion types possible

Ugi chemistry presents an interesting approach to manipulate HA to form novel types of polymer networks (i.e., hydrogels) and/or multiple emulsions. Studies focused on using HA as the carboxylic acid component in the multicomponent Ugi chemistry to generate new biomaterials of possible interest to the field of ophthalmology and for potential controlled delivery systems have been reported (85). 

S. Matsumoto, W/O/W-type multiple emulsions with a view to possible food apphcations, J. Texture Stud. 1986, 17, 141. 

Development of W/O/W Emulsion during Phase Inversion. Sherman et al. (2lQ and Dokic et al.(25) emphasized that the development of a W/O/W type dispersion precedes the thermal induced phase inversion of 0/W emulsions. This suggest that the state of multiple structure in emulsions may be generalized as one of the mesophase between 0/W and W/0 emulsions, and also that there is a possibility of more simplifying the method for preparing W/O/W emulsions. 

Some progress towards an understanding of these systems is possible by considering the influence of the dispersal of water in the oil droplets on the interactions between the multiple drops and by consideration of the influence of the size of the water droplets on their internal stability and on the possibility of coalescence with the external phase. It is premature to consider all this in detail as the application of colloid stability theory to simpler emulsions has not been particularly successful. For type A systems the approach of Void [156] may perhaps be used if the oil layer is thought of as the homogeneous adsorbed layer. Alternatively, the effect of the internal phase on the size of the oil droplet is perhaps worth considering. The approach of Void [156] has been adopted by Florence and Whitehill [150,151] and, in the first instance, interactions tetween identical droplets were considered. In the simplest case two type A droplets may be considered. 

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