Simulation of self-assembly behavior of diblock copolymers under cylindrical shell restriction
In order to investigate the self-assembly behavior of A B diblock copolymers confined in cylindrical shell nanopores,the effects of factors such as the volume fraction of the copolymer,the thickness of the cylindrical shell and the interaction between the copolymer and the surface of the cylindrical shell on the nanostructures formed by copolymer self-assembly were analyzed by simulated annealing technique based on Monte Carlo method.The simulation results show that for diblock copoly-mers with a columnar phase,when long blocks are attracted to the surface of the cylindrical shell,short blocks form spheres,columnar structures,vertical layers and spiral structures with periodic regularity,and pore layer structures are also formed in a certain range of volume fractions.When the surface attracts short blocks,the short blocks first gather on the surface of the column shell until it is full,forming spherical phase,twisted column,stacked ring and spiral degenerate structure inside the column shell.Under the neutral surface,short blocks run through the surface of the shell,forming a series of small balls and short columns.For diblock copolymers with Gyroid body phase,various structures such as vertical layer,parallel layer,pore layer,concentric layer,spiral and connected network structure are formed under the combined action of thickness and surface effect.A series of concentric layers are formed on the strongly selective surface of the diblock copolymer which forms a layered phase in the bulk phase.Through the statistical distribution of the average density of block A along the radial direction of the cylindrical shell,the analysis of cylindrical shell thickness changes shows that with the increase of column shell thickness,the number of concentric layer gradually increases and the thickness of the middle layer is much greater than that of the two layers.There are usually cascaded rings and helical structures under the neutral surface.
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