摘要
通过考察范德华力和静电作用力两个主要因素,建立了一个用以计算双重乳液内、外水相间相互作用能的数学模型。利用此模型,首先计算分析了无吸附层和存在单吸附层时相互作用能的变化趋势,并重点考察了存在两个不同吸附层时此相互作用能的变化。发现在一定的静电作用条件下,随着两个界面间的间距(D)不同,内外水相间的相互作用也有所不同:(1)当D较大时,如果油相的Hamaker常数(AM-M)介于内、外水相的Hamaker常数(AP-P和AC-C)之间,则内外水相间的相互作用始终为微弱的排斥力;否则为微弱的吸引力。(2)当D很小时,如果AM-M介于内、外两个吸附层的Hamaker常数(AA1-A1和AA2-A2)之间,则内外水相间的相互作用表现为较强的排斥力,有利于系统的稳定;否则为吸引力,不利于系统的稳定。
A general mathematic model for analyzing the interaction energy between the internal water droplets and the external aqueous phase of a W1 / O/W2 double emulsion was established. Using this model, variations of the interaction energy between the two aqueous phases were analyzed for different cases, such as there is no absorbed surfactant layer at both interfaces on internal （O/W2） and external （W1/O） aqueous sides, there is only a single absorbed surfactant layer at the interface W1/O or O/W2 and there are two different absorbed surfactant layers at both interfaces W1/O and O/W2. The effects of Hamaker constants of the materials forming the system, especially the Hamaker constants of the two different surfactants （At and A2 ） which form the absorbed layers at the interfaces W1/O and O/W2 separately, on the interaction were investigated. With a certain electrostatic interaction, it is found that the nature of the interaction （repulsive or attractive） between the two aqueous phases W1 and W2 changes with the different separation distances between the interfaces W1/O and O/W2. Specially, in the case when the value of the Hamaker constant of the oil phase is intermediate between those of W1 and W2 and there is a thick oil film separating the two interfaces, a weak repulsive interaction will dominate. If the Hamaker constant of the oil phase is intermediate between those of A1 and A2 and the two interfaces are very close, the interaction between the two aqueous phases will be dominated by a strong repulsive interaction, which helps the system remain stable. In all other cases, the interaction will assume an attractive nature and it will destabilize the system if there is no other repulsive force.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2006年第3期338-344,共7页
Journal of Chemical Engineering of Chinese Universities
基金
北京市科技新星计划(H020821270120)
中国科学院过程工程研究所多相反应重点实验室开放课题(2003-1)
国家自然科学基金(20325621)
教育部留学回国人员科研启动基金
北京化工大学青年教师科研基金(QN0230)资助课题。
关键词
双重乳液
相互作用能
Hamaker常数
范德华力
静电力
double emulsions
interaction energy
Hamaker constant
van der Waals interaction
electrostatic interaction
