奈米乳化是由油、水以及界面活性劑所組成的熱力學穩定系統，其液滴粒徑範圍約10~100 nm。由於這些極微小液滴對光之散射能力較弱，故其外觀呈現透明或半透明狀，對皮膚也有很好滲透力。本研究透過溫度轉相法的方式，探討具有不同碳鏈長度（C）及氧乙烯基（EO）之非離子型界面活性劑，經由轉相變化對奈米乳化的影響。實驗部分使用導電度計來測量不同溫度下的導電度並計算轉相溫度點，利用動態散射粒徑分析儀來測量液滴粒徑的穩定性，藉此計算出老化速率。本研究分為二個部份，分別探討單一型及混合型非離子界面活性劑對於奈米乳化的影響，研究結果顯示隨著界面活性劑的比例濃度的增加，轉相溫度點有呈線性的減少，而且界面活性劑的HLB愈高，其轉相溫度點也跟著有提高的趨勢。在本研究亦探討添加不同油脂比例、以及增稠劑、鹽類（NaCl）對於奈米乳化穩定度的影響，其研究結果顯示添加增稠劑及鹽類並不會提高奈米乳化的穩定性。綜合以上實驗結果得知：界面活性劑的比例、HLB値、轉相溫度點以及油脂的含量為影響奈米乳化的因素。實驗中獲得最穩定奈米乳化粒徑為 25 nm，可穩定儲存於25℃長達三個月以上。 Nano-emulsions are composed of oil-water-surfactant mixtures in a thermodynamics stable system. The droplet size of micellar is approximately 10~100 nm. Because of extremely small size, these droplets have weaker light scattering power, they look like transparency or translucency, and also give well penetration into skin. In this study, the influences of non-ionic surfactants on nano-emulsion formation with different carbon chain length and numbers of ethoxy groups by the phase transfer temperature were investigated. The conductivities during phase transitions were measured to evaluvate the phase inversion temperature. A laser-scattering particles size distribution instrument was used to evaluvate the droplet size at 25oC. This research was divided into two parts: the formation of nanoemulsion with single non-ionic surfactant and the surfactants mixed with two surfactants. The results showed that the phase inversion temperatures increase with the surfactants amounts increased, a linear relation was found for surfactants contents and the PIT. The successful emulsion are dependant on hydrophilic-lipophilic balance (HLB) values. The larger or smallier HLB values can not form stable emulsion. The effect of oil contents, thickening agent and ionic strength on the stabilities of nano-emulsion was also discussed. The higher oil contents, the higher PIT. The higher Oswald ripping rates were also found when thickening agent and NaCl concentration increased in solution.
