Monte Carlo Simulation Of The Self-assembly Of Diblock Copolymer/Nanoparticle Complex Under Different Confinements

The self-assembly behavior of the A₅B₁₅ asymmetric diblock copolymer/nanoparticle mixture under different confinement is studied using Monte Carlo simulation.Two kinds of confinements are employed in this paper,which are parallel wall and cylindrical pore.1.Parallel walls: When A₅B₁₅ asymmetric diblock copolymer/nanoparticle mixture were confined in parallel walls which attract A blocks,the simulation results indicates that the volume fraction of the nanoparticles in diblock copolymer/nanoparticle mixture and the interactions between nanoparticles and each blocks are crucial to the self-assembled structures formed by diblock copolymer/nanoparticle mixture and the distribution of nanoparticles.When the distance between the two parallel walls keep constant,A15B5 asymmetric diblock copolymers can self-assemble into parallel layers in which the mid-layer formed by B blocks are hexagonally perforated.When the nanoparticles which are incompatible with blocks A,while compatible with blocks B are added into the system,increasing the attractive interaction between nanoparticles and blocks B can effectively maintain the hexagonally perforated structure and the pore size in the layer.At this time,the nanoparticles are homogenously distributed in the domain formed by blocks B.However,when the nanoparticles which are incompatible with both blocks are added into the system,a decrease in the repulsive interaction between nanoparticles and block copolymers can benefit for maintaining the hexagonally perforated structure.In addition,when the interaction between nanoparticles and block copolymers is rather weak,the nanoparticles cannot aggregate even if the volume fraction of the nanoparticles is very large,and the nanoparticles homogenously disperse in the interface between A and B phases.2.Cylindrical pores: In this study,the degenerate behavior of self-assembled AB diblock copolymer/nanoparticle mixture in cylindrical pore is studied using Monte Carlo simulation.We find that the degenerate behavior of the self-assembled AB diblock copolymer/nanoparticle mixture in cylindrical pore depends on the introduction of the nanoparticle?NP?.Under different pore sizes,four typical degenerate structures?i.e.,single helices,double helices,parallel cylinders and stacked toroids?can be obtained if the NP content is zero.However,when the NP content in the mixture is increased,it is found that the number of the degenerate structures decreases,i.e.,only blocky structure can be obtained in the case of high NP content.Moreover,the probability for forming single helices decreases,whereas the probability for forming double helices increases with increasing the NP content.It is indicated that entropy plays an important role in the degenerate structure formation by analyzing the chain conformation and the interactive enthalpy densities of the systems.This study provides some new insights into the degenerate behavior of block copolymer/nanoparticle mixture under confinement,which can offer a theoretical reference for corresponding experiments.