Applications of advanced self-consistent field calculations in nanostructured polymeric systems
Date
2009
Journal Title
Journal ISSN
Volume Title
Abstract
The polymer self-consistent field (SCF) theory have gained great success in many systems, especially for the study of inhomogeneous nanostructured polymers. During my PhD study, I have applied real-space SCF calculations with high accuracy to mainly two categories of nanostructured polymers: The first part of this dissertation is focused on the study of self-assembled nanostructures of diblock copolymers (DBC) under nano-confinement. We first examined in detail the so-called "hard-surface" effects, originated from the impenetrable confining surfaces, on the phase behavior of confined DBC systems, where improving the numerical performance of SCF calculations with such effects is also discussed. We then studied in detail the self-assembled morphology of symmetric DBC confined between two homogeneous planner surfaces, where the effects of surface preference and film thickness are investigated and novel complex morphologies are found. Finally, we considered the directed assembly of DBC on topologically and chemically nano-patterned substrates, where well-ordered complex nanostructures can be obtained by controlling the substrate pattern. In the second part of the dissertation, stimuli-response of polymer brushes (chains end-grafted onto a fiat substrate) is investigated. We first studied the thermal response of poly-NIPAM brushes in water, and found that the temperature where the largest thermal response occurs is governed by the chain-grafting density, while the magnitude of the thermal response is controlled by the polymer chain length. We then studied the solvent-response of uncharged DBC brushes and found that the copolymer composition is the key factor in switching the brush surface-layer composition by different solvent treatments; our SCF results agree well with available experimental measurements. Finally, we investigated the stimuli-response of charged DBC. Given the vast parameter space encountered here, we conducted our study based on the uncharged DBC brushes and explored the effects of charge fraction on polymer chains, solution pH and ionic strength, and applied electric fields on the brush surface-switching; this work reveals the complex interplay between different stimuli in such systems. A list of all my published papers and manuscripts in preparation for publication is included at the end of this dissertation, where all the details of my SCF calculations can be found.
Description
Rights Access
Subject
diblock copolymers
polymer brushes
self-consistent field
chemical engineering