微乳液的物理化學特性與穩定度之研究

Study of physicochemical properties and stability of microemulsions

黃博陽(Bo-Yang Huang)

指導教授 ： 陳文章

國立臺北科技大學/工程學院/化學工程研究所/碩士(2011年)

摘要

微乳液是由水、油、界面活性劑和助界面活性劑在適當的比例下自發形成外觀透明或半透明、低黏度和各向同性的熱力學穩定分散系統。微乳液應用在儲存、運輸、包裝和物理等用途，因此在製藥及化妝品領域有極大潛力。
經過篩選而選用肉荳蔻酸異丙酯(IPM)作為油相、聚氧乙烯山梨醇單油酸酯(Tween 80)作為界面活性劑、異丙醇(IPA)為助界面活性劑和水為微乳液的系統，應用滴定法製備微乳液，首先探討微乳液最大溶解水量受不同Tween 80與異丙醇重量比值(Km)的影響，得到最佳Km=1:1、3:2、2:1下佔有相圖最大的微乳相區域面積。選用最佳Km在不同混合界面活性劑比油的比例，繪製在25℃的假三元相圖可推估微乳液所佔的面積大小。使用電導法和染色法鑑別微乳液結構，電導法可測量電導度對含水量的曲線變化，將整個微乳液單相區區分成油包水(W/O)型微乳液、雙連續相(B.C.)型微乳液、水包油(O/W)型微乳液，染色法可同時滴加紅色油性墨水和水溶性染料甲基藍在不同類型微乳液中，比較擴散速度快慢。應用假三元相圖之各組成區域可作為選擇最佳微乳液之配方，且需要結合穩定度的觀察來確定形成微乳液的最佳條件，先由相圖之各組成區域選擇適合的配方，再測量粒徑大小、體積、pH值與溫度變化和表面張力來獲得微乳液穩定度分析結果。
實驗結果顯示經過15天內變化情況，可得到O/W型微乳液之平均粒徑在10~30nm，而pH值範圍為5.16~5.98，體積之變化穩定度順序為Km=3：2 >Km=2：1>Km=1：1，溫度變化中Km=1：1和3：2不會發生相轉變溫度(PIT)，其中Km=2：1判斷出微乳液之相轉變溫度為40℃，表面張力約為30 mN/m。

關鍵字

微乳液 ； 假三元相圖 ； 電導度 ； 穩定度

並列摘要

Microemulsions are clear or translucent, isotropic and low-viscosity, and thermodynamically stable dispersion systems which are spontaneously generated from an appropriate ratio of water, oil, surfactant and cosurfactant. Moreover, microemulsions have great potential in the pharmaceutical and cosmetic field due to the advantageous application in storage, transport, packaging and physics.
After a series of screening tests, isopropyl myristate (IPM) was selected as an oil phase, polyoxyethylene sorbitan monooleate (Tween 80) as a surfactant, isopropyl alcohol (IPA) as a cosurfactant and water as an immiscible phase of the microemulsions. The compositions of microemulsoins were prepared by titration methods. Firstly, optimal formulations of microemulsions at the largest water solubility for different weight ratio (Km) of Tween 80 and isopropyl alcohol were explored and the largest compostion area of microemulsions was acquired at respective values of Km = 1:1, 3:2 and 2:1 through the construction of pseudo-ternary phase diagrams at 25°C. Second, both the conductivity method and dyeing method were adopted to distinguish the biphasic behavior of microemulsions. Conductivity method was used to measure the conductivity of the various weight fractions of the aqueous phase and then categorize the biphasic region of microemulsions into three types of water-in-oil (W/O), bicontinuous (B.C.) and oil-in-water (O/W) microemulsions. Furthermore, dyeing method involved simultaneously adding droplets of oil-soluble red ink and water-soluble methylene blue in different types of microemulsions to compare the dispersion rates of dyes. Subsequently, the optimal formulation of microemulsions was verified by selection of the appropriate compositions of microemulsions within pseudo-ternary phase diagrams and by observation of its biphasic stability. Besides, the long-term experimental stability of microemulsions of the optimal formulations selected from the diagram were investigated through the measurements of parameters like particle size, volume, pH value and surface tension as a function of time at various temperatures.
By observing the changes in stability testing parameters for 15 days, experimental results revealed that average particle size of O/W microemulsions was 10~30nm and the pH value range was 5.16~5.98. Changes of volume for three types of microemulsions indicated that the biphasic stabilities for 15 days decreased in the oder as Km=3：2 >Km=2：1>Km=1：1. As the temperature changed, phase inversion temperature (PIT) for microemulsions prepared with Km=2:1 was 40°C, and its surface tension at 25°C was about 30 mN/m. However, PIT did not occur for microemulsions prepared with Km=1:1 and 3:2.

並列關鍵字

microemulsions ； pseudo-ternary phase diagram ； conductivity ； stability

參考文獻

[10]W. J. Chen, “Polyelectrolyte-Surfactant Interaction and Its Influence on Flocculation and Coalescence of Oil-in-Water Emulsions”, J. Chin. Inst. Chem. Engrs., Vol. 32, No. 2, 95-107, (2001).

[1]吳偉宏，界面活性劑之生物分解、界面相關性質之研究,碩士論文，國立台北科技大學化學工程研究所，(2010)。

[5]邱文慧，荷荷芭油奈米乳液之製備及物性探討，博士論文，靜宜大學應用化學研究所 (2006)。

[7]K. Shinoda, H. Kunieda, Phase properties of emulsions: PIT and HLB in encyclopedia of emulsion technology, Vol.1, P. Becher, Marcel Dekker, Inc., New York, (1983) 337-367.

[11]Th.F. Tadros, P. Izquierdo, J. Esquena, C. Solans, Formation and stability of nano-emulsions, Adv. Colloid Interface Sci. 108-109, 303-318(2004).