Mesoscopic Simulation Studies On The Self-Assembly Of Block Copolymer Under Confinement

The phase separation of block copolymer under confinement was affected by architecture dimension and surface preference. As a result, the systems exhibit different phase behaviors comparing with those in the bulk. The structures under confinement can be used to produce novel nanomaterials. To investigate the self-assembly of block copolymer under confinement by computer simulation method can not only find out the essence of the phase behavior, but also provide a academic guide in predicting experiment results and phenomena. In this paper we studied the self-assembly of bi-block copolymer confined in core-shell cylindrical nanopore and tri-block copolymer confined in core-shell spherical nanopore using Dynamic Density Functional Theory (DDFT). The primary contents and results are as follows:1. Self-assembly of AB bi-block copolymer confined in core-shell cylindrical nanopore was studied by DDFT. The dependence of the self-assembled morphologies and chain conformations on volume fraction, polymer concentration, interaction parameter and architecture dimension were examined systematically. The simulation results indicated that as block copolymer in this 2D confinement, the different volume fraction of block A can induce different novel morphologies, such as the perforate lamella and helix, and the other three factors can also affect the self-assembly morphologies but in different degree. During the simulation, we found a variety of novel, complex structures, and some of them were found even at the first time. By choosing appropriate parameters we observed a structure similar to single-wall carbon nanotube. The appearance of the structure validated the probability to produce single nano-device by confined block copolymer and offered a new idea to produce new functional nanomaterials.2. The self-assembly of ABA triblock confined in core-shell nanopore wereinvestigated. By varying xN and f, four typically morphologies were found, and aphase diagram which described the phase behavior of ABA tri-block copolymer in rough was drawn. The obtained structures include: vesicle, perforate vesicle, hybrid structure and strip pattern. Additionally, the dependence of the self-assembly morphologies on strength of surface-block and surface preference were discussed. As the strength of the surface preference gradually increased, the block was inclined to cover with the surface.3. Investigated the self-assembly of A₄B₉A₄ confined in two nano-spheres anddiscussed the influence of diameter, distance and polymer concentration on the structure. In this 3D confinement, parallel worm-like channel, parallel lamellae, perpendicular cylinders and perpendicular lamellae were found during the simulation. On the study of the two nano-sphere confinement, we can realize the effect of sphere clusters confinement during synthesis hierarchically ordered porous structures by dual template.The paper gives an insight into the controllable structure of bi-block copolymer and tri-block copolymer under confinement and its potential application in nanomaterials. These simulation results give a well understanding for the self-assembly behavior of block copolymers.The characteristic and novelty in the paper are as follows:1. We modified the self-carried computer model in the software by writing a simply program. The changed model was used as physical confinement in the following simulation. And the introduction of this method can extend computer simulation in a large area.2. During the simulation, a variety novel, complex and distinctive self-assembly morphologies were found. We believed that these structures will play an important role in produce nano-materials in future.