Self-organizing Mechanism For The Dimer Particles And Polymers

Soft-matter is an important scientific research field, which correlates to people's daily lives. The scale of the soft-matter is between macro and micro which is re-garded as the mesoscopic world. Soft matter is a complex system of multi-body in-teraction, also known as "complex fluids". The important research content of soft matter is self-organizing behavior of the system, including polymers, colloids, liquid crystal, biomembrane and other complex systems. Our research object is dimer parti-cle/polymer hybrid system. We will study the influence of the morphology of a micelle induced by the dimer particles and the self-assembly behavior of the dimer particles in a supported membrane when the concentration of amphiphilic dimer particles added. In the theoretical approach, we use the self-consistent field theory(SCFT) for polymers and density functional theory(DFT) for dimer particles. Such a study is very helpful for us to understand the self-assembly behavior of complex systems and the relevant phenomena in biology.In the first chapter, we introduce the characteristics of soft materials, the method to obtain the order structures and some typical soft matter. Firstly, we introduce the dif-ference in the contribution to the free energy between soft materials and hard materials. Entropy is the main form of energy for the soft material, and enthalpy is the major part of hard material. Then, we introduce the method to obtain the order structures of soft matter, such as confined induce, substrate induce, environmental induce and doping. At last, we present several soft matters:polymer, colloid, surfactant and biomembrane. Through this chapter, we will have some understanding with the soft-matter. In the second chapter, we introduce several common research methods in the soft-matter. The free-connect model which used to describe polymer chain is deduced, also regarded as the Gaussian model. Then, we introduce two useful methods, they are self-consistent field theory (SCFT) and density functional theory (DFT). Self-consistent field theory used to describe the polymer chain, the theoretical results and experimental results are very consistent. Its advantage is the ability to simplify multi-body interaction as interactions between monomers and field, and concern the conformational entropy of polymer chains. We also note that the self-consistent field theory is a mean-field the-ory, which has its theoretical limitations. The density functional theory is an effective means for the description of colloidal particles which can take the steric repulsion of the particle into account. Through a combination of these two theories, we will have another way in studying colloid/polymer system in the theoretical approach. Finally, we show the process to deal with the dimer particles by using the density functional theory. Though this chapter, we have a viable theoretical approach to study dimer par-ticle/polymer system.In the third chapter, by combining self-consistent-field theory and density-functional theory, we systematically study the deformation of copolymer micelle in-duced by the presence of the amphiphilic dimer particles. Due to the amphiphilic na-ture, dimer particles tend to accumulate onto the interface of the copolymer micelle. With the increasing concentration of the symmetric dimer particles, which are made of two same spherical particles, the micelle deforms from the initial sphere to ellipse, dumbbell, and finally separates into two micelles. Furthermore,we investigate the in-fluence of asymmetric dimer particles, composed by two particles with different sizes on the deformation of the micelle. It is found that the micelle inclines to deform into dumbbell due to the additional curvature originating in the gathering of asymmetric dimer particles onto the interface of the micelle. The present study on the deforma-tion of micelle is useful to understand the possible shape variation in the course of cell division/fusion.In the fourth chapter, by using self-consistent field (SCFT) and density func-tional theories (DFT), we investigate the self-assembly behavior of asymmetric dimer particles in a supported AB block copolymer bilayer. Asymmetric dimer particles are amphiphilic molecules composed by two different spheres. One prefers A block of copolymers and the other likes B block when they are introduced into the copolymer bilayer. The two layer structure of the dimer particles is formed within the bilayer. Due to the presence of the substrate surface, the symmetry of the two leaflets of the bilayer is broken, which lead to two different layer structures of dimer particles within each leaflet of the bilayer. With the increasing concentration of the asymmetric dimer parti-cles, in-plane structure of the dimer particles undergoes sparse square, hexagonal, dense square and cylindrical structures. In a further condensed packing, a bending cylindrical structure comes into being. Here we verify that the entropic effect of copolymers, the enthalpy of the system and the steric repulsion of the dimer particles are three important factors determing the self-assembly of dimer particles within the supported copolymer bilayer.In the last chapter, we summarize what we have done and describe a long-term prospect on the further study of soft matter.