Chen Manman, Zhang Xinghua, Zhang Hui
School of Mathematics Sciences, Beijing Normal University Beijing 100875 China
School of Science, Beijing Jiaotong University 100044 Beijing China.
RSC Adv. 2019 Aug 6;9(42):24394-24400. doi: 10.1039/c9ra05146e. eCollection 2019 Aug 2.
Experiments have shown that worm-like cylindrical micelles can be obtained by extruding spherical micelles through a cylindrical channel. The uniaxial symmetry of the cylindrical confinement can help fuse the spherical micelles into the cylindrical phase. Here, a theoretical model is proposed to investigate this fusion transition driven by external pressure in the cylindrical channel. In this model, spherical micelles are formed by diblock copolymers dissolved in a homopolymer solvent. And the external pressure is controlled by the average center distance of the neighboring spherical micelles. In addition to the fusion transition, the addition of the homopolymers leads to a depletion effect induced by the attraction between adjacent spherical micelles. Thus, spherical micelles in the channel can correlate together and form a linear cluster. The free energy barrier of fusion and the free energy potential well of the clustering of spherical micelles are investigated by a numerical computation of the self-consistent mean field theory. We present a full phase diagram of these transitions depending on the radius of the channel and the external pressure.
实验表明，通过将球形胶束挤压通过圆柱形通道，可以得到蠕虫状圆柱形胶束。圆柱形限制的单轴对称性有助于将球形胶束融合成圆柱形相。在此，提出了一个理论模型来研究由圆柱形通道中的外部压力驱动的这种融合转变。在该模型中，球形胶束由溶解在均聚物溶剂中的两嵌段共聚物形成。并且外部压力由相邻球形胶束的平均中心距离控制。除了融合转变外，均聚物的加入还会导致相邻球形胶束之间的吸引力引起的耗尽效应。因此，通道中的球形胶束可以相互关联并形成线性簇。通过自洽平均场理论的数值计算研究了球形胶束融合的自由能垒和聚集的自由能势阱。我们给出了这些转变的完整相图，该相图取决于通道半径和外部压力。
