Center of Soft Matter Physics and its Applications, School of Physics, Beihang University, Beijing, 100191, China.
Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Macromol Rapid Commun. 2023 Sep;44(17):e2300176. doi: 10.1002/marc.202300176. Epub 2023 Apr 28.
The kinetic paths of structural evolution and formation of block copolymer (BCP) particles are explored using dynamic self-consistent field theory (DSCFT). It is shown that the process-directed self-assembly of BCP immersed in a poor solvent leads to the formation of striped ellipsoids, onion-like particles and double-spiral lamellar particles. The theory predicts a reversible path of shape transition between onion-like particles and striped ellipsoidal ones by regulating the temperature (related to the Flory-Huggins parameter between the two components of BCP, χ ) and the selectivity of solvent toward one of the two BCP components. Furthermore, a kinetic path of shape transition from onion-like particles to double-spiral lamellar particles, and then back to onion-like particles is demonstrated. By investigating the inner-structural evolution of a BCP particle, it is identified that changing the intermediate bi-continuous structure into a layered one is crucial for the formation of striped ellipsoidal particles. Another interesting finding is that the formation of onion-like particles is characterized by a two-stage microphase separation. The first is induced by the solvent preference, and the second is controlled by the thermodynamics. The findings lead to an effective way of tailoring nanostructure of BCP particles for various industrial applications.
使用动态自洽场理论（DSCFT）探索了结构演化和嵌段共聚物（BCP）颗粒形成的动力学途径。结果表明，在不良溶剂中定向自组装的 BCP 会导致形成条纹状的椭圆形、洋葱状颗粒和双螺旋层状颗粒。该理论通过调节温度（与 BCP 两种组分之间的 Flory-Huggins 参数 χ 有关）和溶剂对两种 BCP 组分之一的选择性，预测了洋葱状颗粒和条纹状椭圆形颗粒之间的可逆形状转变路径。此外，还证明了从洋葱状颗粒到双螺旋层状颗粒，然后再回到洋葱状颗粒的形状转变动力学路径。通过研究 BCP 颗粒的内部结构演变，确定将中间双连续结构改变为层状结构对于形成条纹状椭圆形颗粒至关重要。另一个有趣的发现是，洋葱状颗粒的形成具有两阶段的微相分离。第一阶段是由溶剂偏好引起的，第二阶段是由热力学控制的。这些发现为各种工业应用提供了一种有效控制 BCP 颗粒纳米结构的方法。
