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Displaying 1 - 25 of 43

Do Very Small POSS Nanoparticles Perturb s-PMMA Chain Conformations?

July 21, 2018
Author(s)
Nicolas Jouault, Sanat K. Kumar, Robert J. Smalley, Changzai Chi, Robert Moneta, Barbara Wood, Holly Salerno, Yuri B. Melnichenko, Lilin He, William E. Guise, Boualem Hammouda, Michael K. Crawford
Small-Angle Neutron Scattering (SANS) measurements of polymers mixed with weakly attractive 1.0 nm diameter polyhedral oligomeric silsesquioxane (POSS) nanoparticles (NPs) show no observable changes in the chain radius of gyration R g, regardless of the

Mixed Conductive Soft Solids by Electrostatically Driven Network Formation of a Conjugated Polyelectrolyte

February 15, 2018
Author(s)
Scott P. O. Danielsen, Gabriel E. Sanoja, Samantha R. McCuskey, Boualem Hammouda, Guillermo C. Bazan, Glenn H. Fredrickson, Rachel A. Segalman
The microscopic network structure transitions of a conjugated polyelectrolyte (Poly[2,6-(4,4-bis-potassium butanylsulfonate-4H-cyclopenta-[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)], CPE-K) hydrogel were explored with a combination of

The Empirical Core-Chain Model

July 12, 2017
Author(s)
Boualem Hammouda, Man-Ho Kim
Small-angle scattering requires models to analyze the data. A core-chain model has been available to fit data from solutions of core-chain particles. When the core particles are "hard" with well-defined surface, that model has been found to work well and

Mechanistic Insights into the Formation of Porous Carbons from Gelatin

May 1, 2017
Author(s)
A. E. Danks, M. J. Hollamby, Boualem Hammouda, D. C. Fletcher, F. Johnston-Banks, S. E. Rogers, Z. Schnepp
Porous carbons are important for many applications. The biopolymer gelatin provides a simple route to functional carbon foams with77 multimodal porosity. In this paper, small angle neutron scattering is applied alongside other techniques to elucidate the

Structural Analysis of Dendrimers Based on Polyhedral Oligomeric Silsesquioxane and their Assemblies in Solution by Small-Angle Neutron Scattering: Fits to a Modified Two Correlation Lengths Model

December 1, 2016
Author(s)
Guangcui Yuan, Xing Wang, Decheng Wu, Boualem Hammouda
The small-angle neutron scattering (SANS) technique has been used to investigate the structure of dendrimers based on polyhedral oligomeric silsequioxane (POSS). Three generations and two distinct terminal groups (either vinyl or polyethylene glycol (PEG)

Supramolecular Self-assembly of a Novel Hydrogelator: Characterization of Fiber Morphology and Formation and Thermal-Reversible Gelation

October 8, 2016
Author(s)
Jack F. Douglas, Yuan Gao Yuan Gao, Ryan C. Nieuwendaal, Emilios Dimitriadis, Boualem Hammouda, Bing Xu, Ferenc Horkay
Hydrogels are of intense recent interest in connection with biomedical applications ranging from 3-D cell cultures and stem cell differentiation to regenerative medicine, controlled drug delivery and tissue engineering. This prototypical form of soft

Re-entrance of Poly(N,N-diethylacrylamide) in D 2 O/d-Ethanol Mixture at 27degC

July 26, 2016
Author(s)
Di Jia, Taisen Zuo, Sararh Rogers, He Cheng, Boualem Hammouda, Charles C. Han
The re-entrance of poly(N,N-diethyl acrylamide) (PDEA)in D 2O/d-ethanol mixtures (i.e., the coil-to-globule-to-coil transition) has been observed at 27 °C by small-angle neutron scattering (SANS). PDEA has a lower critical solution temperature (LCST) phase

Form Factors for Branched Polymers with Excluded Volume

April 13, 2016
Author(s)
Boualem Hammouda
The form factors for star-branched polymers with linear branches or with looping branches are calculated. The effect of chain swelling excluded volume is incorporated through an excluded volume parameter. Furthermore, the form factor for dendrimers with

Probing Nanoscale Thermal Transport in Surfactant Solutions

October 15, 2015
Author(s)
Fangyu Cao, Ying Liu, Jiajun Xu, Yadong He, Boualem Hammouda, Rui Qiao, Bao Yang
Surfactant solutions typically feature tunable nanoscale, internal structures. Although rarely utilized, they can be a powerful platform for probing thermal transport in nanoscale domains and across interfaces with nanometer-size radius. Here, we examine

Probing the Structure, Composition and Spatial Distribution of Ligands on Gold Nanorods

August 20, 2015
Author(s)
Michael J. A. Hore, Xingchen Ye, Jamie Ford, Yuzhi Gao, Jiayang Fei, Qiong Wu, Stuart J. Rowan, Russell J. Composto, Christopher B. Murray, Boualem Hammouda
The structure and size of ligands attached to the surfaces of gold nanorods, such as adsorbed surfactants or grafted polymers, are important considerations that facilitate the use of such nanoparticles in the human body, in advanced materials for energy

Are Bragg Peaks Gaussian?

March 12, 2014
Author(s)
Boualem Hammouda
It is common practice to assume that Bragg scattering peaks have Gaussian shape. The Gaussian shape function is used to perform instrumental smearing corrections. Using Monte Carlo ray tracing simulation, the resolution of a realistic small-angle neutron

Mesoscale Inhomogeneities in Aqueous Solutions of Small Amphiphilic Molecules

December 15, 2013
Author(s)
Deepa Subramanian, Christopher T. Boughter, Jeffrey B. Klauda, Boualem Hammouda, Mikhail A. Anisimov
Small amphiphilic molecules, also known as hydrotropes, are too small to form equilibrium mesostructures, such as micelles, in aqueous solutions. However, aqueous solutions of nonionic hydrotropes may show the presence of a dynamic, loose, non-covalent

Insight into Neutron Focusing: the Out-of-Focus Condition

October 1, 2013
Author(s)
Boualem Hammouda, David F. Mildner, A. Brulet, S. Desert
A three-pronged approach is used to investigate neutron focusing for small-angle neutron scattering instruments. The three methods are analytical calculations, resolution measurements, and computer simulations. A source aperture containing a single small
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