The Multi-scale Study Of The Complex Polymers Blends System And Lateral Organization Of The Giant Vesicle

Soft matter is closely related to human’s life and lives, and widlyexists in nature, which plays an important role on the development ofmodern industry. The rich domain structures of the copolymersself-assembly also have a good promoting effect on themicroprocessing technology, as well as the new nano materials.The complex polymers blends have great significance due to itspotential application value. At present, there are a lot of researchesabout the simple homopolymer and copolymer system, but theinvestigation of the complex copolymer mixture system in the fieldinduce, the substrate induce and the geometric constrain is few.Thus, comprehensive theoretical studies no doubt will provide anefficient route to understand the soft matter self-assembly as wellas offer some references to the further experimental work. Inaddition, biomembranes can be regarded as a form of the complexcopolymer, which consist of the phospholipids molecules and theprotein. Because of the complexity of the biomembranes structure,we adopt the synthetic membrane model to study the phasebehavior of the biomembranes. The synthetic membranecomposition and structure are not only easier, but also retained some properties of biomembranes. The giant vesicle is one of thewidely used synthetic membranes. The self organization of thebiomembranes has become one of the challenges of modern cellbiology and biophysics. Thus, it is necessary to study theself-assembly of biomembranes.In this thesis, by using the cell dynamical system (CDS) methodand the self-consistent field theory (SCFT), we investigate themulti-scale of the complex polymers blends system and theself-assembly of the giant vesicle. We study the phase behavior ofthe complex polymers in the substrate-induced, field-induced, theconfined system, and the self-assembly of the giant vesicle,respectively. Furthermore, we study the kinetic mechanism of thephase separation.This paper mainly includes the following aspects of content:First, in chapter1, we first briefly introduce the concepts of thesoft matter, polymer, the phase separation theory and the researchmethods. Finally, we analyze the present research situation andprospect.In chapter2, we investigate the orientational order transition ofstriped patterns in microphase structures of diblockcopolymer-diblock copolymermixtures in the presence of periodicoscillatory particles. Under certain conditions, although themacrophase separation of a system is almost isotropic, microphaseseparation of one diblock copolymer takes place and becomesanisotropic gradually. By changing the oscillatory frequency andamplitude, the orientational order transition of a stripedmicrophasestructure from the state parallel to the oscillatory direction to the state perpendicular to the oscillatory direction is observed. We alsofind that the order transition occurs when we change the initialcomposition ratio. Furthermore, we examine the domain size andthe orientational order parameter of microstructure in the processof orientational order transition. The results may provide guidancefor experimentalists. This model system can also give a simple wayto realize orientational order transition of soft materials bychanging the oscillatory field.In chapter3, we discuss the effects of the phase behavior on thesolid substrate of the two diblock copolymers blends filmcontaining the mobile wettable nanoparticles under the modulatedpotential. The system forms the highly ordered microphase andmacrophase structures. We also construct the phase diagram ofthis system upon varying the wetting strength and the modulationamplitude. Simulations suggest that the order striped macrophasestructures are the synergistic effect of the wetting strength and themodulation amplitude, whereas the kinds of different microphasestructures are the effects of the modulation period or theshort-range interactive between monomers. The results show a newcontrol mechanism to stabilize the ordered microphase andmacrophase structures within the copolymer blends film. Thisconclusion provides a simple way to control the order structure ofsoft material.In chapter4, by using a real-space self-consistent field theory,we investigate the phase behavior of the blend of the amphiphilicdiblock copolymer AB and3-arm star homopolymer H confinedbetween two polymer-grafted surfaces. We can control the phase separation via the component’s fraction and the symmetry of thecopolymer. When the component’s fraction in the blend is different,the system has the different phase behaviors due to change thesymmetry of the copolymer. The system forms a transition fromthree-layered lamellar to cylinder, and a four-layered columnstructure. Then we discuss the effect on the phase morphorlogy byvarying the fraction of the star homopolymer. The result shows thatthe system prone to forms hexagonal phase with high fraction of thestar homopolymer due to the architecture of the star homopolymer.The conclusions may provide a helpful guide for experiment.In chapter5, we investigate the effect of architecture on theamphiphilic linear diblock AB, A1A2B, and A2B heteroarm star blockcopolymers confined between two polymer-grafted surfaces. Wefind that the structural transformation from the lamellar tohexagonal phase, and phase behavior of the copolymers arestrongly influenced by the polymer architecture. The conclusionsmay provide a helpful guide for fabricating useful microstructure.In chapter6, we investigate the self-assembly of the giant vesiclewhich is consist of two different phospholipid molecules. The twodifferent phospholipid molecules have the different shapes, thehead and the tail of the phospholipid A is symmetry, the head andthe tail of the phospholipid B is asymmetry. The former’s formationis closely and orderly in biological membranes, whereas the latter’sformation is loose and disorder in biological membranes. Bychanging the fraction of the former phospholipid molecules, themembrane of the giant vesicle forms the “budding” structure. Bychanging the fraction of the latter phospholipid molecules, the membrane of the giant vesicle forms the multilayer membranesstructure. The resultes provide a possible strategy to control andmodulate the domain formation in the giant vesicle, and may yieldsome theoretical insights into the investigation on some cellularprocesses relevant to the biomembranes and design of biosensorsby reorganization of lipids and inclusions.Finally, we summarize this thesis in Chapter7, and give someperspectives in further studies.