Hierarchical and synergistic self-assembly of wormlike micelle-nanoparticle system : A computational investigation

Abstract

We use a wormlike micelle model that uniquely gives us the control parameter to change its excluded volume. We show that the model successfully captures the characteristic behaviour of the wormlike micellar system. Using the Monte Carlo technique, the model wormlike micellar system is observed to undergo an isotropicnematic transition. We also investigate the self-assembly of model nanoparticles inside the matrix of model equilibrium polymers (or matrix of wormlike micelles) as a function of the polymeric matrix density and the excluded volume parameter between polymers and nanoparticles. In this thesis, we show morphological transitions in the system architecture via synergistic self-assembly of nanoparticles and the equilibrium polymers by employing Monte Carlo simulations. In synergistic self-assembly, the resulting morphology of the system is a result of the interaction between both nanoparticles and the polymers, unlike the polymer templating method. We report the morphological transition of nanoparticle aggregates from percolating network-like structures to non-percolating clusters as a result of the change in the excluded volume parameter between nanoparticles and polymeric chains. In parallel with the change in the self-assembled structures of nanoparticles, the matrix of equilibrium polymers also shows a transition from a dispersed state to a percolating network-like structure formed by the clusters of polymeric chains. We show that the shape anisotropy of the nanoparticle clusters formed is governed by the polymeric density resulting in rod-like, sheet-like or other anisotropic nanoclusters. It is also shown that the pore shape and the pore size of the porous network of nanoparticles can be changed by changing the minimum approaching distance between nanoparticles and polymers. We provide a theoretical understanding of why various nanostructures with very different morphologies are obtained.