The viscosity of oil phase decrease with increasing temperature [52], which may facilitate the breakup of the oil-water interface and lead to the formation of smaller droplets. Alternatively, the molecular geometry and solubility characteristics of non-ionic surfactants changes with increasing temperature due to dehydration of their hydrophilic head-groups I44]. The oil solubility of non- ionic surfactants increases with increasing temperature, while the oil-water interfacial tension decreases up to the phase inversion temperature 1371. These two factors may also have facilitated the formation of smaller droplets at higher temperatures due to spontaneous emulsification.