Dynamics of Transitional Phase Inversion Emulsification: Effect of Addition Time on the Type of Inversion and Drop Size

Abstract

Emulsification processes are very sensitive to the time scale during which the dispersed phase is introduced into the continuous phase. A series of experiments were conducted across a transitional phase inversion path, which often leads to formation of nanoemulsions, with the speed of incorporation of the second phase (water) into the first phase (oil) being altered. The optimum condition could only be achieved if the optimum composition was maintained for a critical time. A slow addition (addition time > 60 s) of water to the oil allows the transitional phase inversion to become operative, leading to formation of sub-micrometer droplets. A very fast addition of the water phase (<5.0 s) caused the catastrophic phase inversion mechanism to become dominant, leading to formation of rather large drops. In the intermediate range of addition time, 20−40 s, both inversion mechanisms have contributed to drop formation, at least locally, and as a result skewed or bimodal drop size distributions were formed. The results indicate that while spontaneous emulsification is fast, it is not instantaneous. At a low surfactant concentration, the droplet size was only slightly affected by the rate of addition.

Phase inversion emulsification: Current understanding and applications

“…Other key variables affecting the final emulsion morphology are: i) oil type [72], ii) surfactant type [72], iii) surfactant to oil ratio [72,79,83], iv) initial surfactant location [72], and v) water to oil ratio [84]. Peculiar phase inversion pathways can be optimized in order to obtain microemulsions, nanoemulsions and bicontinuous emulsions with desired features [26,63,79,82,[85][86][87][88][89][90][91][92].…”

Synthesis of Sorbitan Ester Stabilized Uniform Spherical Silver Nanoparticles

“…High energy methods are effective in reducing droplet size and with the aid of proper stabilizer called surfactants. Surfactants can be employed effectively for the synthesis of various nanoparticles 10,11,12 . Generally, sodium borohydride, hydrazine, ascorbic acid and cetyltrimethylammonium bromide, sodium dodecyl sulphate, poly (vinyl alcohol), poly (vinylpyrrolidone), are used as the reducing-and stabilizing-agents respectively to prepare silver nanoparticles with controlled size and shape 13 .…”

Produção por método da temperatura de inversão de fases, estudo de estabilidade físico-química, digestabilidade in vitro e citotoxicidade de nanopartículas lipídicas sólidas encapsulando beta-caroteno

“…A fase que se destina a ser a fase contínua é adicionada à fase dispersa, até que ocorra a inversão de fase e a formação do tipo de emulsão desejada (SAJJADI, 2006). Esta transição de fase resulta da mudança da razão entre a área ocupada pela porção hidrofílica e pela porção hidrofóbica do tensoativo, ou das rupturas interfaciais que ocorrem quando dois líquidos parcialmente miscíveis são misturados e um dos componentes se movimenta de uma fase para outra SADTLER et al, 2010;MEI et al, 2011A;MEI et al, 2011b (IZQUIERDO et al, 2002;MORALES et al, 2006; SAULNIER, 2008;MORAIS et al, 2009;JAHANZAD et al, 2010).…”

“…Tal designação é utilizada pelo fato de ocorrer uma alteração súbita no comportamento do sistema, como resultado da mudança gradual nas condições de processo (ANTON; BENOIT; SAULNIER, 2008;JAHANZAD et al, 2010;SCHALBART et al, 2010). Dentre as inversões catastróficas, o método mais conhecido é a chamado ponto de inversão da emulsão (EIP-do inglês emulsion inversion point).…”

“…(SALAGER et al, 2004;JAHANZAD et al, 2010;SCHALBART et al, 2010). O tipo mais conhecido dentre tais inversões é a inversão de fase por temperatura (PIT -do inglês -phase inversion temperature), que é induzida pela alteração da temperatura enquanto a composição é mantida constante.…”