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Articles 1 - 9 of 9
Full-Text Articles in Engineering Science and Materials
Frontiers In The Self-Assembly Of Charged Macromolecules, Khatcher O. Margossian
Frontiers In The Self-Assembly Of Charged Macromolecules, Khatcher O. Margossian
Doctoral Dissertations
The self-assembly of charged macromolecules forms the basis of all life on earth. From the synthesis and replication of nucleic acids, to the association of DNA to chromatin, to the targeting of RNA to various cellular compartments, to the astonishingly consistent folding of proteins, all life depends on the physics of the organization and dynamics of charged polymers. In this dissertation, I address several of the newest challenges in the assembly of these types of materials. First, I describe the exciting new physics of the complexation between polyzwitterions and polyelectrolytes. These materials open new questions and possibilities within the context …
Polymeric Impulsive Actuation Mechanisms: Development, Characterization, And Modeling, Yongjin Kim
Polymeric Impulsive Actuation Mechanisms: Development, Characterization, And Modeling, Yongjin Kim
Doctoral Dissertations
Recent advances in the field of biomedical and life-sciences are increasingly demanding more life-like actuation with higher degrees of freedom in motion at small scales. Many researchers have developed various solutions to satisfy these emerging requirements. In many cases, new solutions are made possible with the development of novel polymeric actuators. Advances in polymeric actuation not only addressed problems concerning low degree of freedom in motion, large system size, and bio-incompatibility associated with conventional actuators, but also led to the discovery of novel applications, which were previously unattainable with conventional engineered systems. This dissertation focuses on developing novel actuation mechanisms …
Engineering Next Generation Anisotropic Materials And Composites, Nihal Kanbargi
Engineering Next Generation Anisotropic Materials And Composites, Nihal Kanbargi
Doctoral Dissertations
Polymer-based composite systems have been developed for a wide variety of applications ranging from aerospace to electronics. My work has focused on the structure-process-property relationships of anisotropic polymeric materials and composites, aimed primarily for structural applications. Anisotropic materials such as fibers have superior mechanical properties along the axial direction and this property can be exploited to engineer exceptionally strong and light materials. In the first chapter, we discuss the physics of degradation of Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers. PBO, a fiber of extraordinary tensile modulus and strength has been found to degrade rapidly under moderate conditions of humidity and heat. Solid-state NMR …
Deformation And Adhesion Of Soft Composite Systems For Bio-Inspired Adhesives And Wrinkled Surface Fabrication, Michael Imburgia
Deformation And Adhesion Of Soft Composite Systems For Bio-Inspired Adhesives And Wrinkled Surface Fabrication, Michael Imburgia
Doctoral Dissertations
The study of soft material deformation and adhesion has broad applicability to industries ranging from automobile tires to medical prosthetics and implants. When a mechanical load is imposed on a soft material system, a variety of issues can arise, including non-linear deformations at interfaces between soft and rigid components. The work presented in this dissertation embraces the occurrence of these non-linear deformations, leading to the design of functional systems that incorporate a soft elastomer layer with application to bio-inspired adhesives and wrinkled surface fabrication. Understanding the deformation of a soft elastomer layer and how the system loading and geometry influence …
Cold Gas Dynamic Spray – Characterization Of Polymeric Deposition, Trenton Bush
Cold Gas Dynamic Spray – Characterization Of Polymeric Deposition, Trenton Bush
Masters Theses
When a solid, ductile particle impacts a substrate at sufficient velocity, the resulting heat, pressure, and plastic deformation can produce bonding at the interface. The use of a supersonic gas flow to accelerate such particles is known as Cold Spray deposition. The Cold Spray process has been commercialized for some metallic materials, but further research is required to unlock the exciting material properties possible with polymeric compounds. In this work, a combined computational and experimental study a) simulated and optimized the nozzle flow conditions necessary to produce bonding in a polyethylene particle, b) developed and fabricated an experimental device, and …
Effect Of Processing History And Material Properties On The Growth Of Wrinkle Amplitude, Yu-Cheng Chen
Effect Of Processing History And Material Properties On The Growth Of Wrinkle Amplitude, Yu-Cheng Chen
Doctoral Dissertations
Wrinkling has been employed by many organisms to form unique topography, such as fingerprints, gut villi, and surface of flower petal cells. The wavy wrinkle structure provides friction enhancement, surface area increase, optical, and wetting properties improvement. Inspired by Nature, scientists have created wrinkles synthetically and proposed numerous uses for them. However, wrinkling surfaces encounters limitations on achieving massive area and high amplitude-to-wavelength ratio (aspect ratio). The three phase contact line wrinkling technique creates well-defined wrinkles in a continuous fashion, and has great potential to scale-up for massive production. In addition to the velocity dependent adhesion force, we find the …
Mimicking The Arterial Microenvironment With Peg-Pc To Investigate The Roles Of Physicochemical Stimuli In Smc Phenotype And Behavior, William G. Herrick
Mimicking The Arterial Microenvironment With Peg-Pc To Investigate The Roles Of Physicochemical Stimuli In Smc Phenotype And Behavior, William G. Herrick
Doctoral Dissertations
The goal of this dissertation was to parse the roles of physical, mechanical and chemical cues in the phenotype plasticity of smooth muscle cells (SMCs) in atherosclerosis. We first developed and characterized a novel synthetic hydrogel with desirable traits for studying mechanotransduction in vitro. This hydrogel, PEG-PC, is a co-polymer of poly(ethylene glycol) and phosphorylcholine with an incredible range of Young’s moduli (~1 kPa - 9 MPa) that enables reproduction of nearly any tissue stiffness, exceptional optical and anti-fouling properties, and support for covalent attachment of extracellular matrix (ECM) proteins. To our knowledge, this combination of mechanical range, low …
Studies On The Wrinkling Of Thin Polymer Films Floating On Liquid, Kamil B. Toga
Studies On The Wrinkling Of Thin Polymer Films Floating On Liquid, Kamil B. Toga
Doctoral Dissertations
This dissertation aims to broaden our understanding on wrinkling instabilities occurring on floating polymeric sheets, and tries to establish innovative methods that exploit these patterns in studies on material behavior and interfacial phenomena. We will address three major topics in this thesis including, i) characterization of the conditions required to buckle an annular disc, ii) characterization of wrinkles occurring around a droplet/bubble placed on a membrane that is kept taut at the liquid-air interface, and iii) using wrinkling patterns as a probe to understand the interfacial behavior and dynamics of ultrathin films. The first project in this thesis is about …
Self-Assembly Of Block Copolymers By Solvent Vapor Annealing, Mechanism And Lithographic Applications, Xiaodan Gu
Self-Assembly Of Block Copolymers By Solvent Vapor Annealing, Mechanism And Lithographic Applications, Xiaodan Gu
Doctoral Dissertations
Block copolymers (BCP) are a unique class of polymers, which can self-assemble into ordered microdomains with sizes from 3 nm to about 50 nm making BCPs an appealing meso-scale material. In thin films, arrays of BCP microdomains with longrange lateral order can serve as ideal templates or scaffolds for patterning nano-scale functional materials and synthesizing nanostructured materials with size scales that exceed the reach of photolithography. Among many annealing methods, solvent vapor annealing (SVA) is a low-cost, highly efficient way to annihilate defects in BCP thin films and facilitates the formation of highly ordered microdomains within minutes. Directing the self-assembly …