The self-assembly behaviors of AB cyclic symmetric diblock copolymers confined in thin films were investigated by Monte Carlo simulation. The simulation results show that the orientation of the lamellar structure formed by AB cyclic symmetric diblock copolymers in the films depends on the selectivity of the film surface or the film thickness. When the film surface is neutral or has strong selectivity

the orientation of the lamellar is vertical or parallel to the film surface

respectively; When the film surface selectivity is weak

the orientation of the lamellar structure changes from vertical to parallel to the film surface with the increase of the film thickness. These simulation results are in good agreement with the linear systems reported in the literature. However

it is worth noting that when the selectivity of the film surface is moderate

a novel ordered structure with wavy-like structure

not observed in the linear system

is formed in the cyclic copolymer system. By analyzing the interaction enthalpy density and the chain conformation of the structure

it is found that the structure is a stable structure. In addition

by comparing the lamellar structures of the cyclic system and the linear system under the same parameters

it is found that the characteristic size of the lamellar structure of the cyclic system is significantly smaller than that of the linear system. The simulation results above show that compared with linear block copolymers with the same molecular weight

cyclic block copolymers can form novel or smaller characteristic size microphase separation structures due to their special geometric structure. Controlling the characteristic size

especially obtaining the smaller characteristic size

is of great significance for the preparation of microelectronic devices with smaller nanostructures and higher integration.