The Self-consistent Mean Field Theoretic Simulation For The Self-assembly Of ABCBA Linear Pentablock Copolymer

Comparing to the other mean field theory, fewer hypotheses have been used inself-consistent field theory (SCFT). Therefore, SCFT has become an effective method for thestudy of the self-assembly of polymers. Taking AB diblock copolymer as an example, wesystemically intruded the derivation of SCFT equations based upon a standard Gaussian chainin this thesis. We also introduced the numerical technique for solving these equations in thereal space and examined the influence of some parameters on the phase morphology of theAB diblock copolymer.In order to verify our simulation program, we simulated the phase morphology of ABCtriblock copolymers in two dimensions by real space SCFT, and obtained the followingmorphologies: lamellae, lamellae with beads located at the interface, lamellae with beadsinside, hexagonal lattice, tetragonal lattice, core-shell hexagonal lattice, core-shell tetragonallattice, two interpenetrating tetragonal lattice, two interpenetrating hexagonal lattice,hexagonal phase with beads at the interface, tetragonal phase with beads at the interface.Some of them are corresponding to the simulation results in three dimensions.The research in this thesis is focused on the phase behavior of ABCBA pentablock linearcopolymers in two dimensions by using SCFT, and obtained the following results:1. The three-component triangle phase diagram covering the large range of moleculeparameters was made by changing the compositions of the three components systematically.They should be useful for experimenter to design new self-assembly nanostructures throughchoosing the suitable block copolymers.2. When the interaction energies are equal between the three species, the copolymercomposition is a key parameter that influences the morphology due to the equal binaryinteractions between each block. In general, when the volume fractions are comparable,lamellar phases can be found due to the thermal stability. While if one of the volume fractionsis large, hexagonal lattice phases, or core-shell hexagonal phases can be formed. Moreover,lamellae with beads inside can be found by increasing χ N.3. More complex morphologies, such as lamellae with beads located at the interface,interpenetrating belt phases are obtained when the interaction energies between distinctblocks become asymmetric. In addition, the sequence of the blocks is also an importantparameter that affects the phase morphology.