Dissipative Particle Dynamics Study on the Phase Region of Spatial Gradient Materials Produced by Photoinduced Isomerization

Spatial gradient materials occupy an important research position in the field of functional materials with their unique porous structure. Gradient changes in pore size and density distribution have received extensive attention in the fields of biomimetic and smart materials. The gradient transition law is mathematically related to the driving force of isomerization reaction and component phase separation. In this study, a dissipative particle dynamics simulation is used to introduce photoisomerization reactions into the system. Lambert's law is used to construct a reaction model for the variation of light intensity with irradiation depth, and a gradient structure with a spatial transition law is obtained. The effects of the extinction coefficient epsilon, the initial reaction probability Pr0, and the interactions alpha(A,B) between the isomerized molecules as well as the viscosity on the formation of the gradient structure are investigated in detail. Furthermore, the mathematical proportionality between the size of the phase region and interfacial energy of the two phases is elucidated. This study provides preliminary computational insights into the factors affecting the photoinduced phase separation process of polymeric gradient materials. It may help to develop effective strategies to improve the phase separation and properties of polymer gradient materials in subsequent studies. This study uses dissipative particle dynamics simulation method to establish a model to simulate the phase separation process occurring in the photoinduced isomerization system under different influencing factors, to study the effects of different influencing factors on the gradient structure formed by the model, and to explore the mechanism of the gradient structure formation. image