Dr.   Bryan     Vogt

Dr. Bryan Vogt

Department of Polymer Engineering
Phone: 330-972-8608
Email: vogt@uakron.edu

Specific Research Projects

Research in the Vogt group seeks to develop new fundamental knowledge with an eye on manufacturability to address grand challenges facing society. Topics of interest span across disciplines, but is generally connected by the importance of interfaces, the need for improved measurements, and novel processing that can enable improved performance. Although housed in the Department of Polymer Engineering, we do not restrict ourselves to polymers and in many cases the end product is devoid of polymers or polymers are a minor component.

Enhanced Impact Properties from 3D Printing

One common method for the additive manufacture of plastic parts is fused filament fabrication (FFF) where a thermoplastic filament is used as the feedstock and is selectively deposited in a layer by layer manner to build up the part. A serious problem with this printing method is that the part consists effectively of weld lines. These welded interfaces are limited by the diffusion of chains across the interface due to the requirement that the part maintain its printed shape. Our work focuses on developing measurements to understand the temperature and flow conditions that develop during the printing process and then using this understanding to re-design the polymer feedstock to overcome the shortcomings in part properties. One such approach has been the use of core-shell filaments where the core is designed to solidify fast and exhibit a high modulus to prevent deformation of the part while the shell is designed to remain molten for an extended period to relieve the stresses associated with the solidification of the core material (as it will be suspended in a liquid) and to promote the formation of a strong interface between adjacently deposited polymer. This can result in impact strength rivalling injection molded polycarbonate through the introduction of an energy dissipation mechanism associated with delamination of the shell from the core. Mechanically these core-shell materials can behave similar to long fiber composites.

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Manipulating Properties of Water through Confinement

Water is ubiquitous and critical to life, but can render significant damage to engineering structures through the volumetric expansion during crystallization to ice. Ice can lead to cracks in sealants, failure of roads, and serious damage to engineering structures. We seek to determine how to use hydrogels with nanostructured components to manipulate the ordering of water to alter the temperature at which water freezes, the mobility of water in supercooled conditions, and the kinetics associated with phase transitions without the inclusion of salts or other additives.

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Mechanics and Dynamics of Confined Polymers

Thin films of polymers have been used as model systems extensively due to their ability to form stabile ultrathin films that maintain their integrity. These measurements have demonstrated deviations from bulk behavior when probing their thermal properties, which are generally attributed to interfacial effects. However, the impact of these deviations on the mechanical properties is less clear. We seek to provide an improved understanding of the thermoelastic properties of these ultrathin polymer glasses. We utilize a novel approach to probing the mechanical properties of ultrathin (< 100 nm) polymer films exploiting the wrinkling instability resulting from the difference in modulus between a soft substrate (PDMS) and a glassy thin polymer film. Results from this methodology will lead to an improved understanding of the properties of confined polymer systems and will be important for microelectronics where the stability of polymer nanostructures is crucial for device manufacturing.

Our work focuses on trying to understand the fundamental origins of the observed changes in physical properties in polymer thin films. We are particularly interested in determining any relationships between chain structure/architecture and confinement; previous work utilizing a homologous series of poly (n-alkyl methacrylate)s and wide range of molecular mass of polystyrene demonstrated an apparent, direct correlation with the bulk Tg for the thin film modulus. We have also been exploring how additives can impact the size dependent properties as polymers in commercial applications generally contain many different additives.

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Block Copolymer Templated Porous Carbons

Ordered mesoporous carbons have the potential to be ubiquitous materials with potential applications including catalyst supports, membranes for separations, sensors, adsorbents, responsive electrodes, and drug delivery vehicles. Our work focuses on development of improved material properties through processing methods. Control of the structure from the atomic scale to the macroscopic scale is ultimately necessary. We are exploring multiple routes including cooperative self-assembly and vapor infiltration of preformed templates to create materials with the desired morphology. The de-coupling of reaction and self-assembly in the later route could lead to improved control of the final structure.

We seek to modify these carbons to increase its functionality and/or performance especially for electrochemical applications. The motivation for this work is the increased Li capacity of some transition metal oxides, such as TiO2, MnO2, SnO2 and V2O5, in comparison to carbon, but their low electrical conductivity limits charge transfer and hence performance. Furthermore, the charge-discharge reversibility of bulk metal oxides is generally low due to the large volume changes that lead to pulverization of the active material upon successive cycling. Addition of porosity in the material to enable expansion does provide some improvement in the cycling stability for Li battery applications, but additional improvements in cyclability occur when the metal oxide is coated with a thin carbon layer. The carbon can function as physical buffering layer for large volume change. We are actively seeking to understand how morphology impacts the performance of these mesoporous carbon composites. Detailed characterization and systematic processing are utilized to probe these questions.

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Environmentally Benign Processing for Organic Electronics

There has been much effort put into the synthesis of new materials for organic-based electronics and additional emphasis on processing to improve performance. However, the solvent du jour for most polymer electronics is dichlorobenzene, which limits commercial applicability of results from the academic laboratory to an industrial setting. We seek to utilize fundamental concepts from polymer physics and insight from our experience with conjugated polymers to engineer solvent mixtures and additives to enable high performance devices without the use of halogenated solvents. An emphasis is placed upon examining the most environmentally benign solvents possible.

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