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Search Publications by: Jack F. Douglas (Assoc)

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Displaying 251 - 275 of 363

Polymerization Transition in Two-Dimensional Systems of Dipolar Spheres

January 1, 2005
Author(s)
Justin Stambaugh, K VanWorkum, Jack F. Douglas, Wolfgang Losert
We investigate the self-organization of dipolar spheres into polymer chains as a fundamental model of self-assembly of particles having anisotropic interactions. Our study involves a combination of simulation and experiments on vertically vibrated magnetic

Schematic Models of Molecular Self-Organization

January 1, 2005
Author(s)
K VanWorkum, Jack F. Douglas, Wolfgang Losert
Molecular self-organization is central to the formation of numerous biological structures and the emulation of this process through the creation of synthetic counterparts offers great promise for nanofabrication. Our approach to understanding the

Extraordinary Flow Characteristics of Nanotube-Filled Polymer Materials

August 2, 2004
Author(s)
S B. Kharchenko, Kalman D. Migler, Jack F. Douglas, Jan Obrzut, E A. Grulke
Carbon nanotubes are under intense investigation due their potential for modifying the electrical conductivity (s), shear viscosity (h) and other transport properties of polymeric materials. They are hybrids of ordinary filler particles and nanoscale

Near-Field Polarimetric Characterization of Polymer Crystallites

August 1, 2004
Author(s)
Lori S. Goldner, S N. Goldie, Michael J. Fasolka, F Renaldo, Jeeseong Hwang, Jack F. Douglas
We use near-field polarimetry (NFP) to investigate thin film crystallites of isotactic polystyrene (iPS). NFP micrographs enabled quantitative optical characterization of the birefringence in these specimens with sub-diffraction limited resolution

Structural and Dynamic Heterogeneity in a Telechelic Polymer Solution

May 1, 2004
Author(s)
D Bedrov, G D. Smith, Jack F. Douglas
We utilize molecular dynamics simulations to investigate the implications of micelle formation on structural relaxation and polymer bead displacement dynamics in a model telechelic polymer solution. The transient structural heterogeneity associated with

Thermal and Flammability Properties of Polypropylene/Carbon Nanotube Nanocomposites

May 1, 2004
Author(s)
Takashi Kashiwagi, E A. Grulke, J N. Hilding, Richard H. Harris Jr., John R. Shields, Kathryn M. Butler, K M. Groth, S B. Kharchenko, Jack F. Douglas
The thermal and flammability properties of polypropylene/multi-walled carbon nanotube, (PP/MWNT) nanocomposites were measured with the MWNT content varied from 0.5 % to 4 % by mass. Dispersion of MWNTs in these nanocomposites was characterized by SEM and

Comparative Specular X-Ray Reflectivity, Positron Annihilation Lifetime Spectroscopy, and Incoherent Neutron Scattering Measurements of the Dynamics in Thin Polycarbonate Films

April 1, 2004
Author(s)
Christopher L. Soles, Jack F. Douglas, Wen-Li Wu, H G. Peng, D W. Gidley
The manner in which the dynamics of a polymer are affected by thin film confinement is one of technological significance, impacting thin film applications such as lubricants, adhesives, and chemically amplified photoresists. In this manuscript we use

Unusual Expansion and Contraction in Ultrathin Glassy Polycarbonate Films

April 1, 2004
Author(s)
Christopher L. Soles, Jack F. Douglas, Ronald L. Jones, Wen-Li Wu
The thermal expansion behavior and glass transitions of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) are extensively studied in the thin film geometry. Both PS and PMMA are similar in that they possess very low entanglement densities. In this

Finite-Size Effects on Surface Segregation in Polymer Blend Films Above and Below the Critical Point of Phase Separation

March 1, 2004
Author(s)
H Grull, Li Piin Sung, Alamgir Karim, Jack F. Douglas, Sushil K. Satija, Makoto Hayashi, H Jinnai, TT Hashimoto, Charles C. Han
We investigate the influence of temperature and confinement on surface segregation in thin films of deuterated polybutadiene and polyisoprene near the critical point for phase separation. Neutron reflectivity measurements show that polyisoprene enriches at

Non-Linear Transport Properties of Carbon Nanotube Filled Polypropylene

February 1, 2004
Author(s)
S B. Kharchenko, Kalman D. Migler, Jack F. Douglas, Jan Obrzut, E A. Grulke
Dispersal of a relatively small concentration [O(1%) volume fraction] of multiwall carbon nanotubes (MWNT) into polypropylene (PP) is found to cause large and complex changes in nanocomposite transport properties. Specifically, both the shear viscosity h(g
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