In: Journal of Physics: Condensed Matter, 2011, vol. 23, no. 6, p. 065102
Magnetic properties of particles are generally determined from randomly oriented ensembles and the influence of the particle orientation on the magnetic response is neglected. Here, we report on the magnetic characterization of anisotropic spindle- type hematite particles. The easy axis of magnetization is within the basal plane of hematite, which is oriented perpendicular to the spindle axis....
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In: Journal of Physical Chemistry B, 2010, vol. 114, no. 14, p. 4763-4769
Form factor and magnetic properties of silica-coated spindle-type hematite nanoparticles are determined from SAXS measurements with applied magnetic field and magnetometry measurements. The particle size, polydispersity and porosity are determined using a core−shell model for the form factor. The particles are found to align with their long axis perpendicular to the applied field. The...
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In: Macromolecular Chemistry and Physics, 2010, vol. 211, no. 6, p. 635-643
An SANS investigation of hydrated proton exchange membranes is presented. Our membranes were synthesized by radiation-induced grafting of ETFE with styrene in the presence of a crosslinker, followed by sulfonation of the styrene. The contrast variation method was used to understand the relationship between morphology, water uptake, and proton conductivity. The membranes are separated into two...
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In: Macromolecules, 2009, vol. 42, no. 16, p. 6225–6230
We report on the use of hydrostatic pressure, P, to deswell thermosensitive poly(N-isopropylacrylamide) (pNIPAM) microgels and show that it can affect the polymer−solvent mixing as much as temperature, which is the traditional variable used to deswell pNIPAM particles. Interestingly, the microgel volume changes more gradually with pressure than it does with temperature. By comparing the...
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In: Journal of Physics: Condensed Matter, 2009, vol. 21, no. 20, p. 203101
Despite progress in the understanding of crystal nucleation and crystal growth since the first theories for nucleation were developed, an exact quantitative prediction of the nucleation rates in most systems has remained an unsolved problem. Colloidal suspensions show a phase behavior that is analogous to atomic or molecular systems and serve accordingly as ideal model systems for studying...
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In: Physical Review, 2009, vol. 79, no. 5, p. 051403
We present a neutron-scattering investigation of the crystal structure formed by pH-sensitive poly(2-vinylpyridine) microgel particles with 5 wt % of cross-linker. We focus on highly swollen particles and explore concentrations ranging from below close packing to well above close packing, where the particles are forced to shrink and/or interpenetrate. The crystal structure is found to be random...
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