Browsing by Subject "Block polymers"
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Item Data for Boundary Frustration in Double-Gyroid Thin Films(2024-02-29) Magruder, Benjamin R; Morse, David C; Ellison, Christopher J; Dorfman, Kevin D; dorfman@umn.edu; Dorfman, Kevin D; Dorfman Group, UMN CEMSWe have used self-consistent field theory to predict the morphology and preferred orientation of the double-gyroid phase in thin films of AB diblock polymers. A manuscript has been submitted containing this data, and is expected to appear shortly. The data were generated using the C++ version of the open-source software PSCF (https://pscf.cems.umn.edu/). All input and output files from PSCF used to generate the data in the paper are included in this dataset, as well as the code used to process the data and generate the figures.Item Data from: Accelerating self-consistent field theory of block polymers in a variable unit cell(2017-12-04) Arora, Akash; Morse, David C; Bates, Frank S; Dorfman, Kevin D; dorfman@umn.edu; Dorfman, Kevin DThe data contain the results of all the SCFT calculations used to demonstrate the performance of the new algorithm that we devised in our paper: https://doi.org/10.1063/1.4986643Item Graft Polymer Physics(2010-05) Haugan, IngridGraft polymers have polymeric side chains grafted onto a common backbone and exhibit extended conformations due to steric repulsion from densely grafted side chains. The ability to modulate conformation, and thus material performance, has made graft polymers a rich area of research in the last decade. This thesis expands the fundamental understanding of the physical properties of graft polymers in order to aid in the design of novel materials and focuses in three areas: rheology, thermodynamics, and mechanical properties. First, the effect of grafting density on the linear viscoelasticity of graft polymers is investigated. We demonstrate that graft polymers experience the same relaxational modes as linear polymers and their viscoelastic behavior can be described by the same Rouse and reptation theories. The experimental data is compared to scaling models to determine the conformation of the graft polymers, and a new model is proposed to better capture the behavior of experimentally relevant graft polymers. Next, the thermodynamics of densely grafted bottlebrush block polymers is explored. Bottlebrush block polymers were prepared with homopolymer side chains added in blocks along the backbone, varying side chain and backbone length. Their order-disorder transition temperatures were measured by temperature controlled small-angle X-ray scattering. The bottlebrush block polymers display a higher segregation strength compared to linear diblock polymers at the order-disorder transition, indicative of the shielding of the segments near the backbone. The segregation strength at the order-disorder transition decreased with increasing side chain and backbone length. Finally, the mechanical properties of graft polymers with diblock side chains are studied in an attempt to produce tough and sustainable polylactide plastics. The addition of a rubber domain initially toughens the polylactide but the polymers still undergo physical aging and become brittle over time; the time to brittle failure is found to be strongly dependent on the rubber content of the graft block polymers. Pre-straining of the polymers is used to produce stronger and tougher plastics that do not embrittle upon aging.Item Nanoporous thermosetting membranes using reactive block polymer templates.(2010-08) Amendt, Mark A.Pressure driven membrane filtrations are a facile means of performing aqueous separations. The efficiency of these processes depends on the permeability and selectivity of a membrane, which is determined by its structure. This dissertation describes research investigating nanoporous thermosets templated by reactive block polymers as alternatives to current ultrafiltration membranes. The goal of the research was to develop materials with narrow pore size distributions and high void fractions for forming membranes with increased selectivity and permeability. The flux, filtration and fouling characteristics of membranes formed by selective removal of poly(lactide) from crosslinked films of dicyclopentadiene (DCPD) and the reactive block polymer poly(norbornenylethyl styrene-s-styrene)-b-poly(lactide) (PNS-PLA) were first explored. The results suggest that thin film composite membranes could achieve permeabilities and selectivities greater than current ultrafiltration membranes without excessive fouling characteristics. Additionally, hydrophilic and stimuli responsive membranes templated by reactive triblock terpolymers exhibited environmentally dependent fluxes demonstrating the ease of creating functionalized membranes using reactive triblock terpolymers. Further investigation into the compositional influences on the morphology of nanostructured PNS-PLA/PDCPD materials revealed that nanoporous bicontinuous structures form over a wide composition range and that different pore sizes are achievable by varying the PLA block size. Extension of reactive block polymer templating to vinyl crosslinking systems was demonstrated by crosslinking a poly(lactide)-b-poly(cyclooctene-s-norbornenylmethacrylate)-b-poly(lactide) reactive triblock copolymer with a variety of vinyl monomers. Although the soft nature of the poly(cyclooctene) prevented removal of polylactide due to collapse of the pores, nanoporous vinyl thermosets were realized by crosslinking a polylactide-b-poly(styrene-s-hydroxyethyl methacrylate-s-ethylene glycol dimetacrylate) reactive diblock copolymer with styrene and divinyl benzene.Item Polylactide containing block polymers for nanolithography.(2011-01) Rodwogin, Marc DavidThe tendency of block polymers containing two or more immiscible segments to undergo microphase separation and form periodic, compositionally pure domains on the nanometer length scale makes these types of materials attractive for a variety of applications. Through the judicious choice of the constituent chains, block polymers with desirable properties can be fabricated. In particular, this thesis will focus on using these types of materials a nanolithographic templates. We have employed two distinct strategies for the formation of nanoscale arrays: (1) incorporating etch-resistant segments directly into the block polymer, and (2) using external reagents that are resistant to etching as a mask for selected regions of the block polymer. The first half of this thesis will focus on the synthesis and use of block polymers containing both poly(lactide) (PLA) and poly(dimethylsiloxane) (PDMS) as nanolithographic templates. In these systems, the PDMS domains can be selectively oxidized to SiOx, which is highly resistant to subsequent etching steps. Through modulation of the block polymer composition and architecture, we will demonstrate the utility of these types of materials in the formation of nanoscale dot and ring arrays. The second half of this thesis will focus on using block polymers of poly(styrene) (PS) and PLA as well as PS, poly(isoprene) (PI) and PLA in conjunction with additional reagents as etch resistant masks. In these examples, the PLA domains are selectively removed, with the masking reagent residing in the resulting vacancies. These multi-component systems will be shown to be useful for the fabrication of nanoscale dot arrays.