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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Modeling Of Metal-Ferroelectric-Insulator-Semiconductor Structures Based On Langmuir–Blodgett Copolymer Films, Timothy J. Reece, Stephen Ducharme
Modeling Of Metal-Ferroelectric-Insulator-Semiconductor Structures Based On Langmuir–Blodgett Copolymer Films, Timothy J. Reece, Stephen Ducharme
Stephen Ducharme Publications
Among the ferroelectric thin films used in field-effect transistor devices; the ferroelectric copolymer of polyvinylidene fluoride PVDF –CH2–CF2–, with trifluoroethylene TrFE –CHF–CF2–, has distinct advantages, including low dielectric constant, low processing temperature, low cost, and compatibility with organic semiconductors. The operation of a metal-ferroelectric insulatorsemiconductor structure with PVDF-TrFE as the ferroelectric layer was analyzed and optimized by numerical solution of the Miller and McWhorter model. A model device consisting of 20 nm PVDF/TrFE on a 10-nm-thick high-k dielectric buffer exhibits a memory window of 5 V with an operating voltage of 15 V. The operating voltage can be reduced to …
Nanoscale Domain Patterns In Ultrathin Polymer Ferroelectric Films, Pankaj Sharma, Timothy J. Reece, Daniel W. Wu, Vladimir M. Fridkin, Stephen Ducharme, Alexei Gruverman
Nanoscale Domain Patterns In Ultrathin Polymer Ferroelectric Films, Pankaj Sharma, Timothy J. Reece, Daniel W. Wu, Vladimir M. Fridkin, Stephen Ducharme, Alexei Gruverman
Stephen Ducharme Publications
High-resolution studies of domain configurations in Langmuir–Blodgett films of ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), have been carried out by means of piezoresponse force microscopy (PFM). Changes in film thickness and morphology cause significant variations in polarization patterns. In continuous films and nanomesas with relatively low thickness/grain aspect ratio (<1/10), the relationship between the average domain size and thickness follows the Kittel law. Nanomesas with high aspect ratio (>1/5) exhibit significant deviations from this law, suggesting additional surface-energy-related mechanisms affecting the domain patterns. Polarization reversal within a single crystallite has been demonstrated and local switching parameters (coercive voltage and remnant piezoresponse) have been measured by monitoring the local hysteresis loops. Reliable control of polarization at the sub-grain level demonstrates …
Dielectric Nanocomposites: An Inside-Out Approach To Storing Electrostatic Energy, Stephen Ducharme
Dielectric Nanocomposites: An Inside-Out Approach To Storing Electrostatic Energy, Stephen Ducharme
Stephen Ducharme Publications
The ability to achieve high-energy densities is the central challenge in energy storage and recovery. A promising strategy for increasing energy storage is to use highperformance dielectric materials, such as highly polarizable nanoparticles or polymers, or nanocomposites of the two. In this issue, Kim et al. use a molecular coating and clever chemistry to combine oxide nanoparticles with a polymer matrix, thereby producing an improved nanocomposite dielectric. Some advantages and challenges of using nanocomposites as improved dielectric materials are presented in this Perspective.
Synthesis Of Polymers Featuring Novel Diphosphines, Eleanor Tennyson
Synthesis Of Polymers Featuring Novel Diphosphines, Eleanor Tennyson
All Theses
This report details the synthesis of functionalized platinum-based metallopolymers featuring m-terphenyl-scaffolded and light-harvesting phosphine ligands. Substituents placed on both the phosphine and pendant alkynyl units can enhance the optical activity of the metallopolymers depending on their inherent properties. The presence of the platinum metal atom can be exploited to increase conductivity of the molecule and promises to be a unique and valuable modification for polymers to be used in light emitting diodes and photovoltaics. Light-harvesting phosphines prepared in the course of the metallopolymer development have also been used to prepare luminescent polyelectrolytes that prove valuable for well-defined composite film formation …
Polarization Switching Kinetics Of Ferroelectric Nanomesas Of Vinylidene Fluoride-Trifluoroethylene Copolymer, R. V. Gaynutdinov, O. A. Lysova, S. G. Yudin, A. L. Tolstikhina, A. L. Kholkin, V. M. Fridkin, Stephen Ducharme
Polarization Switching Kinetics Of Ferroelectric Nanomesas Of Vinylidene Fluoride-Trifluoroethylene Copolymer, R. V. Gaynutdinov, O. A. Lysova, S. G. Yudin, A. L. Tolstikhina, A. L. Kholkin, V. M. Fridkin, Stephen Ducharme
Stephen Ducharme Publications
The polarization switching kinetics of ferroelectric polymer nanomesas was investigated using piezoresponse force microscopy. The nanomesas were made by self-organization from Langmuir–Blodgett films of a 70% vinylidene fluoride and 30% trifluoroethylene copolymer. The polarization switching time exhibits an exponential dependence on reciprocal voltage that is consistent with nucleation-type switching dynamics.
Optical Properties Of Charged Polymer With Nano-Sized Zeolite Inclusions, Temenujka Yovcheva, Izabela Naydenova, Ivanka Vlaeva, Rosen Todorov, Vincent Toal, Simeon Sainov
Optical Properties Of Charged Polymer With Nano-Sized Zeolite Inclusions, Temenujka Yovcheva, Izabela Naydenova, Ivanka Vlaeva, Rosen Todorov, Vincent Toal, Simeon Sainov
Conference Papers
The optical characteristics of photopolymer films doped with nanoparticles are studied. The investigated systems consist of a soft polymer matrix containing porous zeolite nanoparticles with concentrations varied in the range from 0wt.% to 7wt.%. 40μm thick layers are obtained by casting the photopolymer nanocomposite solution on glass substrates. The corona charging influence on the transmission spectra and on the surface and the effective refractive index of the dry layers is investigated.
Normal Stiffness Calibration Of Microfabricated Tri-Layer Conducting Polymer Actuators, Michael J. Higgins, Gursel Alici
Normal Stiffness Calibration Of Microfabricated Tri-Layer Conducting Polymer Actuators, Michael J. Higgins, Gursel Alici
Faculty of Science - Papers (Archive)
This paper reports on the stiffness characterization of microfabricated tri-layer conducting polymer (PPy) actuators. The rectangular, polypyrrole microactuators, which could operate both in aqueous and non-aqueous media, were fabricated using an excimer laser ablation technique that provided high throughput production and did not require cleanroom facilities. The microactuators were fixed at one end with electrical contacts and the other was end free to act as an electroactive microcantilever beam. An atomic force microscope (AFM) was used to measure the microactuator deflection under a range of normal forces applied by the AFM cantilever. A modified reference spring constant calibration method was …
Synthesis And Physical Studies Of Polycarbonate Of P-Tert-}Butylcalix[4]Arene: A Highly Selective Receptor For Na^+, Muhammad Ashram, Nawash Al Ghezawi, Ibrahim Abu Awaad, Gülsen Asman
Synthesis And Physical Studies Of Polycarbonate Of P-Tert-}Butylcalix[4]Arene: A Highly Selective Receptor For Na^+, Muhammad Ashram, Nawash Al Ghezawi, Ibrahim Abu Awaad, Gülsen Asman
Turkish Journal of Chemistry
The synthesis and characterization of a polycarbonate of p-tert-butylcalix[4]arene 4 are reported. It was synthesized by condensation of p-tert-butylcalix[4]arenetetraol derivative 3 with ethyl chloroformate. This new polymer possesses a hydrolyzable backbone and tunable hydrophobic/hydrophilic properties. The experimental results indicate that the polycarbonate was successfully synthesized with average molecular weight \overline{M}_{w}, (2.328 \times 10^4 g/mol), which was determined by static light scattering method using a Berry plot. The structure of this polymer was determined by IR spectroscopy. The thermal properties were investigated using differential scanning calorimetry (DSC). The degree of crystallinity was measured by means of XRD. The extraction ability of …
Creep Behavior Of Natural Fiber Reinforced Polymer Composites, Yanjun Xu
Creep Behavior Of Natural Fiber Reinforced Polymer Composites, Yanjun Xu
LSU Doctoral Dissertations
Creep behavior of natural fiber/polymer composites (NFPCs) was studied in response to the increasing application of this material as structural building products. Factors that influence creep behavior of the composites were investigated by analyzing creep curves of several different NFPC systems, which were designed for overall performance of the composites. Among different models, the 4-element Burgers type was mostly used for quantitative characterization of the creep curves to compare the properties of different composites. The parameters from the 4-element Burgers model were easily interpretable due to their physical meanings. Generalized Burgers models provided better fit by introducing extra Kelvin units, …