The Directed Self-assembly Of Diblock Copolymers In Selective Solvents Using Simulated Annealing Method

The self-assembly of the block copolymer can be a rich nanostructure,including spherical,rod-like,layered,vesicle,spiral,ring and other structures,and these rich structures in the functional devices,drug delivery,or other emerging application technology have a potential application value.Therefore,in recent years,the self-assembly behavior of block copolymers has become one of the hot topics of nano-preparation technology,which has aroused great interest in many researchers.Factors that affect the self-assembly of the block copolymers generally include the composition of the block,the concentration of the solvent,and the confined environment.Therefore,in this paper,the simulated annealing method was used to investigate the self-assembly of AB diblock copolymers in solvent,and self-assembly of AB diblock copolymers in soft confinement and self-ssembly behavior of the blends of AB diblock copolymers and C homopolymer in soft confinement.The simulation results show that these factors can accurately adjust the morphology of aggregates.The obtained simulation results can be used to guide and design the structure of nanoparticles,so it can be used as a guide and reference for experiments.Specifically as follows:(1)The effect of self-assembly of diblock copolymers in the solvent was investigated by adjusting the shape and size of the inducer and the interaction parameters between the components.The simulation results show that the morphology of the aggregates changes from cylindrical to tadpole to round or banded micelles as the size and shape of the inducer change.Likewise,the shape and size of the inducer are the same,and the morphology of the aggregates is also affected as the interaction parameters of the A block and the induced surface are enhanced.The mechanism of the morphological transformation is expounded by calculating the mean square end-to-end distance and contact number in aggregates.(2)The effect of self-assembly of diblock copolymers in the soft confinement was investigated by adjusting the size of the confinement,the initial concentration ofthe solvent and the interaction parameters between the components.The simulation results show that changing the confinement size,the morphology of the aggregates changed from a rod like structure to helix to semi-elliptical honeycomb structure;with increasing of the initial concentration of the solvent,the morphology of the aggregates changed from rod like to multi helix to single helix to ring structure.The mechanism of this morphological transition is illustrated by calculating the number of contacts between the AB blocks in aggregates and the interface energy of the system and the variation of the projection DDX on the X-axis after the AB chain stretching in aggregates.(3)The effects of the blends of AB diblock copolymers and homopolymers on the self-assembly behavior in soft constants were investigated by adjusting the size of confinement,the number ratio of AB diblock copolymers to C homopolymers,the volume fraction of blocks,the selectivity of confinement's surface,the incompatibility between blocks,and the competition between two block-homopolymer interactions.The sequence of the different shape and internal structure of the copolymer formed under soft confinement is predicted and the simulation results show that these factors can accurately adjust the morphology of aggregates.The mean square end-to-end distance as a function of initial concentration for AB diblock copolymers in aggregates is calculated to illustrate the mechanism of the morphological transformation.