| The thermodynamic behavior of ordered structures (lamellae and cylinders) of diblock copolymer systems has been studied, both in the bulk and in thin films confined between two hard surfaces. At temperatures below the order-disorder transition, the morphology of diblock copolymers A-B exhibits an intrinsic periodicity on the length scale of tens of nanometers; these materials therefore have great potential applications in nano-fabrication.; Two kinds of important size effects are investigated by extensive bulk simulations: the match between the intrinsic periodicity of the ordered structures and the periodic boundary conditions employed in the simulations, and the capillary-wave broadening of A-B interfaces. The simulation results have also been quantitatively compared with predictions of the self-consistent mean-field theory for bulk lamellae of symmetric diblock copolymers in a neutral, good solvent.; For applications of block copolymer thin films in nano-lithography, it is crucial to control both the orientation and ordering (in the plane of the film) of the thin-film morphology. To examine the feasibility of a newly proposed strategy of guided self-assembly, i.e. using chemically nano-patterned substrates to induce the desirable perpendicular structures having an in-plane long-range (over microns or longer) order, extensive simulations have been performed for diblock copolymers confined between either homogeneous or nano-patterned surfaces. Based on the simulation results, the strong-stretching theory is applied to construct phase diagrams of the system of interest. The combined simulation-theoretical study presented here provides a systematic understanding on the effects of the film thickness, the surface-block interactions, as well as the dimensions and symmetry of the substrate pattern, on the thin-film morphology. It provides evidence in support of the principle of guided self-assembly, it reveals the necessary conditions under which this strategy can work, and it serves as a useful guide for optimal experimental design.; With the goal of using microphase-separated block copolymers to position nano-particles or functional homopolymers, a study has also been presented regarding the behavior of a single particle and a single homopolymer chain in the ordered structures of copolymers. Throughout this work, simulation results have been qualitatively compared with available experimental observations, and good agreement between the two has been obtained. |
