Dissipative Particle Dynamics Study Of Microstructures Of Complex Block Copolymer Systems

Block copolymer, as a main branch of polymer material, has received increasing attention recently from both scientific and practical point of view. The block copolymer with complex structures can self-organize into various microstructures due to the microphase separation in melt and in solution, which may find wide use in the design and synthesis of new materials with unique properties. In this work, the microphase separation of block copolymer melt, the micelles formed by the self-assembly of block copolymer in solution as well as modeling of the properties of polymers with the connectivity index are proposed. The main results obtained are:1. Microphase separation and properties of novel linear-dendritic diblock copolymers are discussed under steady shear flow using Dissipative Particle Dynamics method. The results show that their microstructures and properties depend on both the shear rate and the degree of branching, and linear-dendritic diblock copolymers are a kind of promising new material with unique properties that may find wide applications in the future.2. The microstructures of block copolymer nanocomposites with binary nanoparticles mixtures are studied. The results indicate that the self-assembly of nanoparticle mixtures in polymer matrix is a cooperative assembly that is affected by various factors. And these may provide molecular-level information for the rational design of new polymer nanocomposites with tailored properties.3. The self-assembly of triblock copolymers melt with different architectures are simulated under steady shear flow. Different triblock copolymer melts can form the same morphology, but they have different responses to the shear rate depending on the difference between the architectures of block copolymers.4. The study of multicompartment micelles formed from multiblock copolymers in solution is proposed. The simulations reveal some novel morphologies which have not been reported in experimental work. At the same time, the influences of the length and the length ratio of blocks as well as the quality of solvent on the morphology of micelles are discussed in detail, with providing the formation mechanisms and visualizing the evolution process of multicompartment micelles at a molecular level. 5. Three different kinds of particles can be selectively distributed in the segregated compartments in multicompartment micelles with core-shell-corona structure simultaneously by choosing appropriate volume ratio and interaction parameters. And the presence of one kind of particle may influence the distributions of other particles.6. The variable connectivity index is used in the modeling of the physical properties of polymers. A new model is proposed for the heat capacity at constant pressure of solid and liquid polymers at room temperature, which is simple and has good accuracy as well as predictive capability.