Self-assembly Of Polymer Nanocomposites-Field-and Particle-based Simulations

With the development of technology, high-performance new materials with tailoredproperties are in great demand. Polymer nanocomposites are one of the promisingmaterials which have been widely applied in industry. In this thesis, we integrated theself-consistent field theory (SCFT) and Monte Carlo simulation method to study thethermodynamic equilibrium structure of nanoparticles with grafting copolymer chains ontheir surface and the interactions between these surface-modified nanoparticles.The hybrid method integrates both the advantages of field-based and particle-baseddescriptions that keep the information of detailed structure and fluctuation effect and,meanwhile, the efficiency of simulation. We applied the method to the single nanoparticlegrafted with AB diblock copolymer chains and found the chain of the same species mergestogether. The B chains in the outer shell can form droplets structure due to mutualattraction. We also investigated the interactions between two surface-grafted nanoparticles.As the two nanoparticles get close, the grafted copolymer chains between two particlesmerge together, and the distance between the two nanoparticles have a great effect on theirstable structure.Besides the polymer nanocomposites, we studied the “continuous vs. discrete”problem in the SCFT. We took the diblock copolymer melts as an example. First, we seekthe equilibrium structures predicted by SCFT which contains nonintegral numbers ofchains in a unit cell. We want to compare the results with particle-based simulations toshow how this “continuous” description leads to nonrealistic equilibrium structures and whether there can be automatic defects which are caused by non-commensuration insteadof thermal fluctuation. This part of work is still ongoing.