Computer Simulation On The Self-assembly Of Block Copolymers With Rigid Ends In Planar Slit

The self-assembly behavior of block copolymer within nanoscale confinement is one of themost important research topics in the field of soft matter. It is found to be dependent on theproperty and dimension of confinements, thus resulting in the formation of various orderedstructures different from those assembled in bulk. However the exact mechanism is still not clearand needs systematic study. In this thesis, dissipative particle dynamics (DPD) simulations arecarried out to investigate the self-assembly of rod-coil block copolymers within a nanoslit. Itmainly includes the following two parts:(1) Self-assembly of rod-coil diblock copolymers within a planar slit. The assembledstructures of rod-coil diblock copolymers R5C13within a planar slit are investigated via DPDsimulations. The effects of the property and height of slit have been studied. It is found thatwithin the rod-selective slit, rod blocks change from the wetting layer into cylinders parallel tosurfaces. And hexagonally packed cylinders perpendicular to surfaces are observed before theincrease in the number layer of parallel cylinders. Paralell cylinders of rod blocks are alsoassembled within strong coil-selective slit. However, no perpendicular cylinders are observed instrong coil-selective slit. Whereas in weak coil-selective slit, hexagonally packed cylindersperpendicular to surfaces are always assembled independent of the slit height.(2) Self-assembly of rod-coil-rod triblock copolymers within a rod-selective slit. The effectsof the rigidity of the rod block, the interaction between the slit surface and the rod block on theassembled structures of R4C12R4rod-coil-rod triblock copolymers are systematically investigatedvia DPD simulations. And a phase diagram is obtained. Within the strong rod-selective slit, thestructure changes from parallel lamellae to wave-like lamellae, perpendicular lamellae, andultimately to hexagonally packed cylinders perpendicular to the slit surfaces with the increase ofthe ridigity of the rod block. The perpendicular lamellae will become the stable structure with thedecrease of the attraction between the slit and rod block. In the moderate rod-selective slit, thestructure can change from hexagonally packed cylinders to wave-like lamellae, perpendicularcylinders and then to complex structure of hexagonally packed cylinders near the surfaces andperpendicular lamellae at interior of slit with the increase in the slit height.