A Simulation Study On The Self-Assembly Of Rod-coil Triblock Copolymers Under One-dimensional Confinement

Block copolymers have received considerable attentions due to their ability to self-assemble into various ordered superstructures. Recently, confinements are often adopted to achieve precise control of the orientation of self-assembled structures,and a series of novel structures with various potential applications are obtained. In this thesis, dissipative particle dynamics(DPD) simulations are performed to systematically investigate the self-assembly behavior of rod-coil triblock copolymers within a planar slit. It is divided into two parts as follows:(1) Self-assembly of rod-coil-rod(RCR) triblock copolymers confined within a slit. The self-assembly behavior of sphere-forming R5C30R5 triblock copolymer within a planar slit is studied by performing DPD simulation. It is demonstrated that the assembled structures are strongly dependent on the property of slit and the slit height. The results are summarized in a phase diagram. A sequence of novel structures which are not observed in bulk are formed within slits, including wetting layers, island-like structure, parallel cylinders, hexagonally-packed perpendicular cylinders and cross-cylindrical structures. The layer number of parallel cylinders increases with the slit height. Hexagonally-packed perpendicular cylinders are always formed before the increase in the layers of parallel cylinders. Within strong C-selective slits, interesting cross-cylindrical structures are formed. The effect of the rod length is also investigated. And the rod length is found to have a significant impact on the rod alignment. Some special structures, such as a curved strip-shaped structure, parallel half-cylinders and arrowhead-shaped morphology, are observed when the rod length increases to a certain extent.(2) Self-assembly of rod-coil-coil?(RCC?) triblock copolymers within a slit. DPD simulations are performed to investigate the self-assembly behavior of gyroid-forming R4C6C?2 triblock copolymers within a planar slit. Hexagonally packed perpendicular cylinders are formed for both R-selective and C?-selective slits, and the number of perpendicular cylinder layers increases with the slit height. However, different processes for the structural transition are observed. Within R-selective slits, perpendicular lamellae are always formed before the increase in the layers of perpendicular cylinders. While for C?-selective slits, parallel “three-color” lamellae are preferred to be formed. For C-selective slits, perpendicular lamellae with different orientations in different layers is generally observed by increasing the slit height, and the perforated lamellar phase is often formed in the interior region due to the contact of perpendicular lamellae in different layers. Our simulation results show that the self-assembly of RCC? triblock copolymers are sensitively dependent on the property and the height of slit. Meanwhile, the rod block significantly influences the self-assembly behavior of gyroid-forming triblock copolymers, resulting in the generation of three-dimensional ordered structures.