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利用耗散粒子动力学(DPD)模拟方法研究了三种不同结构的Pluronic嵌段共聚物F127,F68和L64在油水界面处的自组装行为.结果发现,嵌段共聚物的分子量、PO/EO比例以及油水体积比等因素对PEO-PPO-PEO类三嵌段共聚物的界面构型、界面张力和界面厚度等均具有一定的影响;PO/EO比值愈大且分子量较大者,体系界面张力越低,界面厚度越大;嵌段共聚物的PO/EO的比值接近时,分子量较小者界面张力较低,界面厚度较小.F68分子中的PO嵌段含量低于F127,但因其分子量小,故其PO嵌段在界面处排列更紧密有序,界面张力更低.同时,研究发现油水比例的增加会使油/水/嵌段共聚物体系的构型由水包油型乳状液向油包水型乳状液逐渐转变;油水比例对嵌段共聚物聚集行为的影响与其分子量的大小有关:分子量较大者,油水比对其界面性能影响较大,分子量较小者则影响不大.
The self-assembly behavior of three different Pluronic block copolymers F127, F68 and L64 at the oil-water interface was investigated by dissipative particle dynamics (DPD) simulation. The results showed that the molecular weight of the block copolymers, PO / EO PEO-PPO-PEO triblock copolymer, the interfacial tension and interfacial thickness of PEO-PPO-PEO triblock copolymer have certain effects. The larger the PO / EO ratio is and the larger the molecular weight is, The lower the tension is, the larger the interface thickness is. When the ratio of PO / EO is close to the block copolymer, the interfacial tension is lower and the interface thickness is smaller with the smaller molecular weight. The PO block content in F68 molecule is lower than F127, Its molecular weight is small, so its PO block in the interface arranged more closely and orderly, lower interfacial tension.At the same time, the study found that the ratio of oil to water will make the oil / water / block copolymer system configuration from oil-in-water The emulsion changes gradually to the water-in-oil emulsion. The effect of the ratio of oil to water on the aggregation behavior of the block copolymer is related to its molecular weight. The larger the molecular weight, the greater the oil-water ratio is, the smaller the molecular weight is Not big.