Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong, 250100, PR China.
Langmuir. 2012 Oct 16;28(41):14547-52. doi: 10.1021/la302995a. Epub 2012 Oct 1.
Oil-in-water nanoemulsions were produced in the system water/Span 80-Tween 80/paraffin oil via the phase inversion composition (PIC) method at elevated temperature. With the increase of preparation temperature from 20 to 70 °C, we found that the emulsion droplet diameter decreases from 10.3 μm to 51 nm, proving the formation of nanoemulsions. The viscosity of nanoemulsions clearly increases with droplet volume fraction, φ, but the droplet size changes less. Significantly, at φ ≤ 0.5, the size distribution of nanoemulsions can be kept unchangeable more than 5 months. These results proved that the highly viscous paraffin oil can hardly be dispersed by the PIC method at 25 °C, but the increase in preparation temperature makes it possible for producing monodisperse nanoemulsions. Once the nanoemulsion is produced, the stability against Ostwald ripening is outstanding due to the extremely low solubility of the paraffin oil in the continuous phase. The highly stable nanoemulsions are of great importance in practical applications.
水包油纳米乳剂是通过相转变组成（PIC）法在高温下于水/司盘 80-吐温 80/石蜡油体系中制备的。随着制备温度从 20°C 升高到 70°C，我们发现乳液液滴直径从 10.3μm 减小到 51nm，证明了纳米乳剂的形成。纳米乳剂的粘度明显随液滴体积分数φ增大而增大，但液滴尺寸变化较小。重要的是，在φ≤0.5 时，纳米乳剂的粒径分布可在 5 个月以上保持不变。这些结果表明，在 25°C 时，高粘度的石蜡油很难通过 PIC 法分散，但升高制备温度可使单分散纳米乳剂的制备成为可能。一旦制备出纳米乳剂，由于石蜡油在连续相中的极低溶解度，其对奥斯特瓦尔德熟化的稳定性非常出色。高度稳定的纳米乳剂在实际应用中具有重要意义。
