摘要
建立了对应实验体系聚乙烯/聚氧化乙烯/聚乙烯-聚氧化乙烯嵌段共聚物(PE/PEO/PE-PEO)的对称三元共混模型,并采用耗散粒子动力学(DPD)模拟方法对其相行为进行了理论研究.研究结果表明,随着均聚物体积分数的增加,体系的平衡相态发生由层状相(LAM)到双连续微乳液(BME)再到相分离(PS)的转变,相态演化规律和相区位置与实验结论基本一致,并且BME相在理论预测的Lifshitz点附近.对各种相态及相转变过程采用有序参数、结构因子以及密度分布等手段进行表征,结果表明,在LAM相区,均聚物的溶胀作用使得层间距随均聚物体积分数的增加而增大;在PS相区,随着嵌段共聚物体积分数的增加,体系的界面张力不断降低直至零;在BME区,BME结构中界面处的嵌段共聚物分子处于无序状态,对应着BME相结构的弯曲界面.并且,结构因子的计算结果表明BME结构与Teubner-Strey微乳散射模型定性一致.此外,界面张力的计算结果还表明形成稳定BME结构时体系的界面张力值极低.
A coarse-grained model for symmetric ternary blends was constructed based on an experimental system of polyethylene/polyethylene oxide/polyethylene-poly（ethylene oxide）（PE/PEO/PE-PEO） used in Bates＇s work,and dissipative particle dynamics（DPD） method was employed to study the phase behavior of such ternary blends.Density distribution,order parameter and structure factor were used to characterize the phase and phase transition.The results show that the phase changes from lamellar（LAM） to bicontinuous microemulsion（BME） and then to macroscopic phase separation（PS） as the volume fraction of homopolymers ΦH is increased.The phase sequences and their locations are in accordance with the experimental results.Especially,the BME region is located near the theoretical Lifshitz point.The LAM spacing increases with increasing ΦH in LAM region and the interfacial tension decreases with increasing volume fraction of diblock copolymer（1-ΦH） in PS region.Diblock copolymer molecules are disordered at interfaces due to the nature of curved interfaces in BME phase.The calculated structure factor on the BME structure is qualitatively in agreement with the Teubner-Strey static scattering model of microemulsion.In addition,the interfacial tension should reduce to a very low value in order to form stable BME structure.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2011年第5期530-536,共7页
Acta Polymerica Sinica
基金
国家自然科学基金(基金号20874110
20674093)资助项目
关键词
粗粒化
耗散粒子动力学
对称三元共混
相行为
双连续微乳液
Coarse-grained
Dissipative particle dynamics
Symmetric ternary blend
Phase behavior
Bicontinuous microemulsion
