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Search Publications by: Alamgir Karim (Assoc)

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Displaying 1 - 25 of 101

Characterization of Elastomeric Blends by Atomic Force Microscopy

October 12, 2021
Author(s)
P Achalla, Jennifer L. McCormick, T Hodge, C Moreland, P Esnault, Alamgir Karim, H Raghavan
The bulk mechanical properties of a blend of elastomers are found to depend on the micro and nano scale morphology of the phases of the materials in the blend. In this paper, we examine the phase morphology of blends of incompatible elastomers using Atomic

Fluctuation Effects on Surface Pattern Formation in Thin Block Copolymer Films

October 12, 2021
Author(s)
A C. Smith, Jack F. Douglas, Eric J. Amis, Alamgir Karim
Hole formation on the surface of thin block copolymer films is investigated as a function of time (t), temperature (T) and film thickness. The size of the holes, h s, approaches a steady state value at long times h s,∞ = h s(t -> ∞) and we introduce a

Temperature Effects on Surface Pattern Formation in Thin Block Copolymer Films

October 12, 2021
Author(s)
A P. Smith, Jack F. Douglas, Eric J. Amis, Alamgir Karim
Hole formation on the surface of thin films of symmetric diblock copolymers is investigated as a function of time, t, temperature, T, and film thickness, h. The size of the holes approaches a steady state value at long times and their long-time size is

Structure, Nanomechanics and Dynamics of Dispersed Surfactant-Free Clay Nanocomposite Films

February 22, 2018
Author(s)
Xiao Zhang, Jing Zhao, Chad R. Snyder, Abdullah Al-Enizi, Ahmed Eltazahry, Alamgir Karim
Using additives to tailor the performance of polymeric materials is perhaps one of the most important aspects for producing materials of advanced applications. The exploitation of nanoparticle dispersion strategies have been broadly investigated for tuning

Solvent Retention In Thin Spin-Coated Polystyrene And Poly(Methyl Methacrylate) Homopolymer Films Studied By Neutron Reflectometry

January 19, 2010
Author(s)
Xiaohua Zhang, Kevin G. Yager, Shuhui Kang, Nathaniel J. Fredin, Bulent Akgun, Sushil K. Satija, Jack F. Douglas, Alamgir Karim, Ronald L. Jones
We utilize neutron reflectometry (NR) to probe the amount of residual solvent inside thin polystyrene (PS) and poly(methyl methacrylate) (PMMA) films spin-coated from deuterated toluene polymer solutions onto silicon substrates . The effect of thermal

Application of Thermal Gradients to Achieve Orientational Order in Block Copolymer Thin Films

August 18, 2009
Author(s)
Nathaniel J. Fredin, Brian Berry, Kevin G. Yager, Alamgir Karim, Sushil K. Satija, Deanna Pickel, Ronald L. Jones
The development of methods that permit control over the long-range order and orientation of microdomains in block copolymer (BCP) thin films for bottom-up approaches to nanoscale surface patterning is of great interest for many applications, including

Dielectric Spectroscopy Investigation of Relaxation in C60-Polyisoprene Nanocomposites

March 23, 2009
Author(s)
Yifu Ding, Sebastian Pawlus, Alexei Sokolov, Jack F. Douglas, Alamgir Karim, Christopher Soles
We investigate the influence of adding C60 nanoparticles on the dielectric relaxation spectra of both unentangled and entangled polyisoprene (PIP). Relaxation modes corresponding to both segmental and chain relaxation were analyzed over a broad temperature

Disordered Nanoparticle Interfaces for Defect-Tolerant Self-Assembly

November 17, 2008
Author(s)
Kevin G. Yager, Brian Berry, Kirt A. Page, Derek L. Patton, Alamgir Karim, Eric J. Amis
Self-assembly is a promising route for controlling the nanoscale structure and material properties of coatings, yet it remains difficult to control the microstructure of these systems. In particular, self-assembling materials typically have complex and

3D Cellular Morphometrics With Multi-Scale Topographical Constraint

October 16, 2008
Author(s)
A Sehgal, Alamgir Karim, Eric J. Amis
The three dimensional cytoplasmic spread of osteoblast like MC3T3-E1 cells with substrate topography was investigated by atomic force microscopy (AFM). The analysis of AFM images as applied to an ensemble of cells from programmed multiple scans under

Crystallization of Poly(ethylene oxide) on Topographically Patterned Substrates

October 16, 2008
Author(s)
Brian C. Okerberg, Christopher Soles, Jack F. Douglas, Alamgir Karim
Crystallization of poly(ethylene oxide) (PEO) on topographically patterned substrates is investigated. Primary nucleation was dramatically enhanced during solvent drying on patterned substrates compared to flat films. The nucleation density also increased

Entanglement Effects on the Dewetting of Polymer Thin Films

October 16, 2008
Author(s)
K A. Barnes, Alamgir Karim, Jack F. Douglas, Da-Wei Liu, Eric J. Amis
We investigate the dewetting of entangled and unentangled polymer films from model viscous polymer and inorganic substrates. Linear and hypergraft polyethyloxazoline (PEOX) polymers are chosen as the unentangled and entangled dewetting fluid, respectively

Image Analysis for High-Throughput Materials Science

October 16, 2008
Author(s)
Alamgir Karim, A Sehgal, J C. Meredith, A J. Crosby, Eric J. Amis
Imaging plays a key role in modern day materials science by providing a high-density format of data representation that can be visually interpreted or processed by the human brain in a fraction of a second. We have illustrated a few select examples-

Morphological Changes in Thin Polypropylene Films Induced by 4-Biphenyl Carboxylic Acid

October 16, 2008
Author(s)
Marlon L. Walker, Chad R. Snyder, Naomi Eidelman, E S. Etz, A P. Smith, Alamgir Karim, Eric J. Amis
The crystallization behavior of thin polypropylene films both neat and containing a nucleating agent, 4-biphenyl carboxylic acid, was investigated by optical microscopy, atomic force microscopy, infrared spectroscopy and Raman spectroscopy. High-throughput

NIST Combinatorial Methods Center, July 10, 2001: Meeting Proceedings

October 16, 2008
Author(s)
A Sehgal, Alamgir Karim, Eric J. Amis
The meeting showcased combinatorial research and methods development at NIST as applied to materials science problems. The Combinatorial Methodology is a set of tools and techniques the chemicals and materials science communities will use to accelerate the

Polymer-Surface Interactions in Nanfilled Polymers

October 16, 2008
Author(s)
Alamgir Karim, Jack F. Douglas, A Nakatani, Eric J. Amis, D B. Majumdar
We review recent investigations of conventional and nanoparticle filled polymers using atomic force and optical microscopy, scattering (x-ray, neutron and visible light) to characterize the influence of filler particles on the phase separation morphology

Spinodal Dewetting on Chemically Patterned Substrates

October 16, 2008
Author(s)
A Sehgal, V Ferreiro, Jack F. Douglas, Eric J. Amis, Alamgir Karim
We utilize chemically patterned substrates with arrays of progressively narrower stripes (1-15 mm) to investigate the influence of pattern size on the morphology of dewetting polystyrene films. The early-stage dewetting patterns align with the substrate

Swelling of Grafted Polymer Brushes

October 16, 2008
Author(s)
Jack Douglas, M S. Kent, Sushil K. Satija, Alamgir Karim
The end-grafting of polymer chains to surfaces provides a robust method for modifying surface properties. Such layers are increasingly being employed in applications-modifying the biocompatibility of implants, the wetting, adhesive and frictional

Wetting-Dewetting Transition Line in Thin Polystyrene Films

October 16, 2008
Author(s)
K M. Ashley, D T. Raghavan, Jack F. Douglas, Alamgir Karim
Thin polymeric films are increasingly being utilized in diverse technological applications and it is crucial to have a reliable method to characterize the stability of these films against dewetting. The parameter space that influences the dewetting of thin