中文摘要：

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.

英文摘要：

The dissipative particle dynamics（DPD） simulation method was used to simulate the self-assembly behavior of three triblock copolymers,EO106PO70EO106,EO80PO30EO80 and EO13PO30EO13,at the oil/water interface.Gaussian chain is used to represent the three triblock copolymers.The effects of molecular weight,PO/EO ratio and oil/water volume ratio on the aggregation behavior of the copolymer were discussed in our simulation.The simulation results indicate that the triblock copolymer aggregate at the oil/water interface at lower concentration.The PEO groups of copolymer chains are immersed in the water phase while the PPO groups are located close to the oil phase.With the concentration of copolymer increasing,some copolymer chains begin stretch into the bulk.Copolymers can self-assemble into micelles in the water phase when the surface is saturated.The PEO groups are in the surface of micelles and some oil beads in the core,and this is in good agreement with the experimental results concerning their structures.In addition,molecular weight,and the ratio of PO/EO and oil/water have great effect on the interfacial properties（interfacial density,interfacial thickness and interfacial tension） and structural properties of the triblock copolymers.We found that the oil/water/copolymer system has lower interfacial tension and higher interfacial thickness when the copolymer has higher PO/EO ratio and larger molecular weight.If the value of PO/EO ratio is similar,the interfacial tension and interfacial thickness increases with molecular weight.Though the PO/EO ratio of F68 is lower than F127,the arrangement of F68 chains at the interface is more compact because of its lower molecular weight.With oil/water ratio increasing,O/W type emulsion is gradually transformed to a W/O type emulsion for the oil/water/copolymer systems.Furthermore,the effect of oil/water ratio on the self-assembly behavior of block copolymer is related to its molecular weight.Significant effect is observed for larger molecular weight of triblock copolyme