Influence Of UV Light To The Phase Behavior Of The PS-AA-PMMA And Its Ternary System

With the development of science and technology,self-assembled block copolymers are widely used in industrial manufacturing technology and people's daily life.It can connect two or more polymers with excellent properties and make them self-assemble to form abundant microstructures,which can greatly promote the development of microfabrication technology and nanomaterials preparation technology.This has attracted the attention of a large number of researchers,making it a hot research object in the field of polymer research.In this paper,we use the Time-Dependent Ginzburg-Landau?TDGL?equation to simulate the effects of UV light on the microstructures of PS-AA-PMMA and its ternary mixtures,and analyze the reasons for the microstructural changes.Firstly,the kinetics of PS-A and PMMA-A under ultraviolet irradiation was simulated,in which-A refers to the functionalization of anthracene on the polymer chains.By designing the order parameters,the range of TDGL equation to simulate the composition ratio of block copolymers L is increased.Then,the soybean-like and noodle-like structure of PS-AA-PMMA can be obtained at L?0.3 or L?0.7 and L=0.5 respectively.When L=0.4 or L=0.6,the bead-like and noodle-like structures coexist.The structure of PS-AA-PMMA tend to be more orderly and smaller by increasing the light intensity.Subsequently,in the ternary system,a weak UV light is set as background light to illuminate the whole simulation area,and then some rectangular areas with higher intensity of UV light are set up.The results show that when the illumination intensity in the rectangular region is the same as that in the background,the elliptical X phases?X could be SiO₂ or TiO₂?are randomly distributed in the layered PS-AA-PMMA and gradually gather together.When the illumination in the rectangular area is stronger,X phases will gather in the rectangular area and form a regular rectangle.Meanwhile,PS-AA-PMMA block copolymer with periodic layered distribution can be obtained in regular X phases by changing the distance between rectangular regions and background ultraviolet light intensity.Then,we studied the microstructural changes of PS-AA-PMMA with different composition ratios under UV irradiation coupled with chemical templates.A periodic stripe substrate was added to the bottom of PS-AA-PMMA for controlling the directional self-assembly of block copolymer PS-AA-PMMA to form large-area regular,orderly and undefect stripe-like and bead-like microstructures.Finally,the microstructures of PS-AA-PMMA block copolymers were simulated in a three-dimensional model.The results show that with the increase of shear rate at the composition ratio L=0.2,the block copolymers will change from the parallel hexagonal cylinder phase to the perpendicular hexagonal cylinder phase.With the increase of shear rate at the composition ratio L=0.3,the system will change from the perpendicular hexagonal cylinder phase to the parallel hexagonal cylinder phase.These kinetic pathways have been reported for the first time in this paper.When the shear rate continues to increase,the simulation results show the transition from the hexagonal cylinder phase into the layered phase.The results also show that the layered phases with different widths can be obtained by changing the proportion of block copolymers under a certain shear rate.The simulation results in this paper provide theoretical support for the study of how to obtain block copolymers with long-range ordered defect-free structure,and help to realize the application of this material in the fabrication of micro-electronic devices and nano-materials.