Calculation of Droplet Size from Interfacial Area

Calculation of Droplet Size from Interfacial Area 

Assuming all surfactant and cosurfactant molecules are adsorbed at the interface, it is possible to calculate the total interfacial area of the microemulsion from a knowledge of the area occupied by surfactant and cosurfactant molecules. 

Total interfacial area = Total number of surfactant molecules x area per surfactant molecule As + total number of cosurfactant molecules x area per cosurfactant molecule A . 

A is related to the droplet radius R (assuming all the droplets are of the same size) by 

Using reasonable values for Ag and A o (30 for NaDBS and 20 for hexanol) R was calculated and the results compared with those obtained using light scattering results. Two conditions were considered (a) All hexanol molecules were adsorbed lAl (b) Part of the hexanol adsorbed to give a molar ratio of hexanol to NaDBS of 2 1 (1A2). 

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