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Full-Text Articles in Physics

Hyperthermal H2 Induced C–H Bond Cleavage: A Novel Approach To Cross-Linking Of Organic Molecules, Tomas Trebicky Sep 2011

Hyperthermal H2 Induced C–H Bond Cleavage: A Novel Approach To Cross-Linking Of Organic Molecules, Tomas Trebicky

Electronic Thesis and Dissertation Repository

The development of simple and effective methods of incorporating molecular moieties with desirable properties into new functional materials is one of the ultimate goals of material scientists. The work presented in this thesis demonstrates an easy way to accomplish this using a beam of gaseous H2, which we call hyperthermal hydrogen induced cross-linking (HHIC). We prove theoretically and experimentally that when the kinetic energy of H2 is raised to ~20 eV, it becomes a light-mass projectile which is energetic enough to knock hydrogen atoms off of organic molecules, but not other heavier atoms. By developing a reactor …


Study Of The Shrinkage Caused By Holographic Grating Formation In Acrylamide Based Photopolymer Film, Mohesh Moothanchery, Izabela Naydenova, Vincent Toal Jun 2011

Study Of The Shrinkage Caused By Holographic Grating Formation In Acrylamide Based Photopolymer Film, Mohesh Moothanchery, Izabela Naydenova, Vincent Toal

Articles

We study the shrinkage in acrylamide based photopolymer by measuring the Bragg detuning of transmission diffraction gratings recorded at different slant angles and at different intensities for a range of spatial frequencies. Transmission diffraction gratings of spatial frequencies 500, 1000, 1500 and 2000 lines/mm were recorded in an acrylamide based photopolymer film having 60 ± 5 μm thickness. The grating thickness and the final slant angles were obtained from the angular Bragg selectivity curve and hence the shrinkage caused by holographic recording was calculated. The shrinkage of the material was evaluated for three different recording intensities 1, 5 and 10 …


Shape Selection Of Twist-Nematic-Elastomer Ribbons, Yoshiki Sawa, Fangfu Ye, Kenji Urayama, Toshikazu Takigawa, Vianney Gimenez-Pinto, Robin Selinger, Jonathan Selinger Apr 2011

Shape Selection Of Twist-Nematic-Elastomer Ribbons, Yoshiki Sawa, Fangfu Ye, Kenji Urayama, Toshikazu Takigawa, Vianney Gimenez-Pinto, Robin Selinger, Jonathan Selinger

Robin Selinger

How microscopic chirality is reflected in macroscopic scale to form various chiral shapes, such as straight helicoids and spiral ribbons, and how the degree of macroscopic chirality can be controlled are a focus of studies on the shape formation of many biomaterials and supramolecular systems. This article investigates both experimentally and theoretically how the chiral arrangement of liquid crystal mesogens in twist-nematic-elastomer films induces the formation of helicoids and spiral ribbons because of the coupling between the liquid crystalline order and the elasticity. It is also shown that the pitch of the formed ribbons can be tuned by temperature variation. …


Dynamics Of Nanoparticles In Complex Fluids., Rami Ahmad Saleh Omari Jan 2011

Dynamics Of Nanoparticles In Complex Fluids., Rami Ahmad Saleh Omari

Wayne State University Dissertations

Soft matter is a subfield of condensed matter including polymers, colloidal dispersions, surfactants, and liquid crystals. These materials are familiar from our everyday life- glues, paints, soaps, and plastics are examples of soft materials. Many phenomena in these systems have the same underlying physical mechanics. Moreover, it has been recognized that combinations of these systems, like for example polymers and colloids, exhibit new properties which are found in each system separately. These mixed systems have a higher degree of complexity than the separate systems. In order to understand their behavior, knowledge from each subfields of soft matter has to be …


Length Scales Of Interactions In Magnetic, Dielectric, And Mechanical Nanocomposites, Ralph Skomski, Balamurugan Balamurugan, Eva Schubert, Axel Enders, David J. Sellmyer Jan 2011

Length Scales Of Interactions In Magnetic, Dielectric, And Mechanical Nanocomposites, Ralph Skomski, Balamurugan Balamurugan, Eva Schubert, Axel Enders, David J. Sellmyer

Axel Enders Publications

It is investigated how figures of merits of nanocomposites are affected by structural and interaction length scales, Aside from macroscopic effects without characteristic lengths scales and atomic-scale quantum-mechanical interactions there are nanoscale interactions that reflect a competition between different energy contributions. We consider three systems, namely dielectric media, carbon-black reinforced rubbers and magnetic composites. In all cases, it is relatively easy to determine effective materials constants, which do not involve specific length scales. Nucleation and breakdown phenomena tend to occur on a nanoscale and yield a logarithmic dependence of figures of merit on the macroscopic system size. Essential system-specific differences …