Download or read book Self-assembly of Block Copolymers and Polymer Brushes written by Wei Wei and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-assembly of block copolymer materials (BCPs) and polymer brushes in the sub-50 nm length scale are explored in this thesis. BCPs and mixed polymer brushes have the ability to self-assemble into well-ordered structures which are ideal for surface patterning, templating and growth of nanomaterials. Compared to the extensively studied morphologies resulting from BCPs, phase behavior of mixed brushes is experimentally less explored, mainly due to the synthetic and characterization challenges. In this thesis we derive from the studies in the BCP self-assembly in thin films to study the melt phase behavior of mixed brushes on a planar substrate. In the first part of the thesis we study the thin film assembly of a strongly phase-separating cylinder forming poly(styrene-b-2 vinylpyridine) (PS-b-P2VP). The cylinders are used to template arrays of sub-20-nm-wide molybdenum disulfide (MoS2) nanowires. In the second part of the thesis we develop a synthetic route to grow uniform, high-grafting density polymer brushes with controlled brush length on planar substrates. This method starting from an initiator coating overcomes all the previous synthetic challenges. This chemistry is first tested by growing a mixed brush poly(methyl methacrylate)/polystyrene (PMMA/PS). We validate for the first time the predicted morphology for mixed brush in melt using the PS/PMMA. The deviation from the expected phase behavior as we move to strongly segregating PS/P2VP mixed brush system is discussed. Lessons learned from the thin film assembly of the PS-b-P2VP in the first part of the thesis led to the largely unexplored area of chain-end effects on morphology in mixed polymer brushes. Potential solutions towards the self-assembly of PS/P2VP mixed bushes in melt is discussed. Three major contributions are made in this thesis: 1) development of an universal method to synthesize A/B mixed brushes with uniform grafting of A/B chains; 2) development of a model to experimentally evaluate the grafting densities of the two brushes; and 3) discovery of chain end effect on thermal stability of mixed brushes and its influence on the morphology. This thesis paves the way for synthesizing mixed brushes with unprecedented level of control, hence opening up new phase behavior and potential surface patterning methods.