以网状结构为导向的嵌段共聚物体系的场论研究

Block copolymer self-assembly provides a robust platform for the fabrication of ordered nanostructures with the feature size of 5-100 nm which have potential applications in a wide range of fields, and thus it has attracted continuously increasing interest. For the simple AB type block copolymers, the self-assembled ordered morphologies typically include sphere, cylinder, gyroid and lamella. Among the mesostructures, the network morphologies are especially interesting because of their three-dimensionally co-continuous and interpenetrated, which exhibit the merits of high porosity and huge interfacial area and thus generate potential applications in a wide range of areas. While the reported stable network morphologies self-assembled by block copolymers is the double gyroid, the others are metastable or are only stable in very narrow phase regions and therefore are difficult to be obtained in experiments. The main goal of the present proposal is to exploit design principles of architectures of block copolymers and combine the polymer blending method to design block copolymer systems for the fabrication of stable targeted interesting network structures. The self-consistent field theory (SCFT) with special initialization method is used to determine the stability of these targeted structures and reveal the formation mechanism. Then this project will provide useful theoretical guides for the fabrication of mesoscale network structures.

三维有序贯通的网状结构具有广泛的应用前景而备受关注，但是目前嵌段共聚物体系所形成的主要网状结构只有Gyroid，其他网状结构通常为亚稳态或者具有非常狭窄的稳定区域，实验上难以获得。该项目，发展嵌段共聚物分子结构的设计原理，并结合共混的方法，设计嵌段共聚物体系，实现具有显著稳定相区的目标结构——非Gyroid网状结构。拟采用基于特殊初始化方法的自洽平均场理论计算预测所设计嵌段共聚物体系的相图，验证目标网状结构的稳定性，并揭示它们的形成机理。为实验或应用中制备各种介观尺度的网状结构提供理论指导。

嵌段共聚物能自组装形成10-100纳米有序的结构从而拓宽了其在纳米材料上的应用，但是通过简单的嵌段共聚物自组装形成的结构非常有限，特别是具备特殊应用的结构更难获得。本项目通过发展嵌段共聚物分子结构的设计原理，为目标结构设计嵌段共聚物体系，利用自洽平均场理论（Self-consistent field theory, SCFT）方法验证目标结构的稳定性，并揭示了它们的形成机理。主要获得了以下几个研究成果：（1）针对穿孔网状结构，设计了一维薄膜受限的AnB星型聚合物体系和ABAT分叉聚合物体系，计算了包含穿孔结构的相图，探究了分子结构和受限尺寸对穿孔结构稳定性的影响；（2）针对螺旋结构，设计了二维圆柱受限的AB两嵌段共聚物体系，ABC三嵌段共聚物体系，和ABC/C共混体系，成功获得了螺旋数从1到6连续可调的螺旋结构，并揭示了不同体系下螺旋数不同的螺旋结构之间的相转变机理；（3）采用两种简单AB两嵌段共聚物共混的方法预测了多种稳定的Frank-Kasper (FK) 复杂晶体结构，揭示了来自于长短不同分子链的同类嵌段的局域相分离促进这类具有非均一的配位数、形状和尺寸球的复杂晶体结构的形成机理。研究结果能为特殊应用的聚合物材料所需目标结构的制备提供有意义的理论指导。项目执行期间发表标注基金编号的SCI论文5篇。