Gao Hanyang, Hu Guoxin, Liu Kun, Wu Liqun
School of Mechanical Engineering, Hangzhou Dianzi University, Xiasha Higher Education Zone, 310018 Hangzhou, Zhejiang Province, China.
School of Mechanical and Power Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, 200240 Shanghai, China.
Ultrason Sonochem. 2017 Nov;39:520-527. doi: 10.1016/j.ultsonch.2017.05.032. Epub 2017 May 22.
Waterborne nanoemulsion of diglycidyl ether of bisphenol A type epoxy resin (DGEBA) with droplet size of around 124nm was prepared by using an ultrasonic-assisted supercritical carbon dioxide (scCO) technique in an autoclave reactor at a low temperature (32°C). A view cell positioned in-line with the ultrasonic probe allowed observation of the emulsification process. From the image analysis and droplet size measurement, the influence mechanisms of the ultrasonic power, the degree of mixing of scCO with DGEBA, the adding amount of emulsifier, and the system pressure on emulsification process and emulsion droplet size were investigated. In the emulsification process, scCO penetrated into the mixture and absorbed on the DGEBA molecular. The interactions between CO and the functional groups of DGEBA reduced the chain-chain interactions of polymer segments and therefore efficiently reduced the viscosity of DGEBA at a low temperature. Meantime, the cavitation and acoustic streaming of ultrasound provided a shear force for the nanoemulsification and a disturbance force for the homogeneity of the emulsion. Therefore, the combination of scCO and ultrasonication made it possible to prepare a long-term stable nanoemulsion under a low temperature. This ultrasonic-assisted scCO emulsification method provides an efficient and solvent-free process for the preparation of waterborne nanoemulsions of, for example, some heat-sensitive and water-insoluble active substances at low temperature.
采用超声辅助超临界二氧化碳（scCO₂）技术，在低温（32°C）的高压釜式反应器中制备了双酚A型环氧树脂（DGEBA）的水性纳米乳液，其液滴尺寸约为124nm。一个与超声探头同轴放置的视窗单元可用于观察乳化过程。通过图像分析和液滴尺寸测量，研究了超声功率、scCO₂与DGEBA的混合程度、乳化剂添加量以及系统压力对乳化过程和乳液液滴尺寸的影响机制。在乳化过程中，scCO₂渗透到混合物中并吸附在DGEBA分子上。CO₂与DGEBA官能团之间的相互作用降低了聚合物链段之间的链间相互作用，从而在低温下有效降低了DGEBA的粘度。同时，超声的空化作用和声流为纳米乳化提供了剪切力，并为乳液的均匀性提供了扰动力。因此，scCO₂与超声处理相结合使得在低温下制备长期稳定的纳米乳液成为可能。这种超声辅助scCO₂乳化方法为在低温下制备例如一些热敏性和水不溶性活性物质的水性纳米乳液提供了一种高效且无溶剂的工艺。
