Anne Juggernauth - Academia.edu (original) (raw)
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Papers by Anne Juggernauth
Advanced Functional Materials, Aug 9, 2010
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We use rheology and Small Angle X-Ray Scattering (SAXS) to investigate UV initiated gel formation... more We use rheology and Small Angle X-Ray Scattering (SAXS) to investigate UV initiated gel formation in aqueous dispersions of clay nanoparticles in the presence of poly(ethyleneoxide-b-propyleneoxide-b-ethyleneoxide) block copolymer surfactants (Pluronics) and small amounts of a photoacid generator (PAG). This material system demonstrates stable liquid-like behavior in the absence of UV but undergoes bulk gelation upon UV exposure. Rheology was used to monitor the bulk properties of a series of samples undergoing UV exposure and confirm bulk gel formation. We further probe nanoparticle rearrangement using time resolved synchrotron SAXS with simultaneous UV exposure. Time dependent SAXS indicate an absence of long range order and crystallinity while changes in the scattering profile are related to short range interparticle interactions leading to a stable or arrested structure. Finally, we compare the time scales for structural rearrangement of nanoparticles with the bulk gelation beha...
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Soft Matter, 2011
ABSTRACT In situ photorheology experiments were conducted to investigate the kinetics of UV-trigg... more ABSTRACT In situ photorheology experiments were conducted to investigate the kinetics of UV-triggered photogelation of aqueous Laponitenanoparticle dispersions formulated with less than 10 wt% of a triblock copolymer (PluronicF127) and diphenyliodonium-2-carboxylate monohydrate, a photoacid generator (PAG). We show that gelation kinetics depend strongly on solution composition and intensity of UV light used during in situ photorheology experiments. A decrease in gelation rate was observed with increasing Pluronic F127 concentrations while higher PAG and Laponite concentrations result in higher gelation rates. Changing the intensity of UV light from 100 mW cm−2 to 150 mW cm−2 at a constant composition reduced the exposure time required prior to onset of gelation by half. Finally, the effect of Laponite and PAG on the micellization of F127 was probed using differential scanning calorimetry (DSC). The results show that the presence of Laponite particles and PAG suppresses the enthalpic endotherm associated with micelle formation in solutions containing up to 7.2 wt% PluronicF127. Using these results, we present a detailed mechanism for the photogelation phenomenon as well as the parameters surrounding intelligent design and formulation of these systems.
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Nanoscale, 2010
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Macromolecules, 2011
Aqueous solutions of polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) triblock copo... more Aqueous solutions of polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) triblock copolymers (commercially available as Pluronic surfactants) micellize and structurally arrange into cubic quasicrystalline lattices as their temperature is raised. This structural evolution is seen macroscopically as a gelation, and the presence of these ordered phases can be controlled through both polymer concentration and temperature. The presence of added solutes within the dispersions can also
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Advanced Functional Materials, 2010
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Advanced Functional Materials, 2010
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Acta Materialia, 2007
Using the in situ optical technique known as digital image correlation (DIC), full-field quantita... more Using the in situ optical technique known as digital image correlation (DIC), full-field quantitative strain maps of localization have been experimentally obtained for the first time in thin sheets of Nitinol. The use of DIC provides new information connecting previous observations on the micro- and macro-scales. It shows that the transformation initiates before the formation of localized bands, and the
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Advanced Functional Materials, 2012
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Bookmarks Related papers MentionsView impact
Advanced Functional Materials, Aug 9, 2010
Bookmarks Related papers MentionsView impact
We use rheology and Small Angle X-Ray Scattering (SAXS) to investigate UV initiated gel formation... more We use rheology and Small Angle X-Ray Scattering (SAXS) to investigate UV initiated gel formation in aqueous dispersions of clay nanoparticles in the presence of poly(ethyleneoxide-b-propyleneoxide-b-ethyleneoxide) block copolymer surfactants (Pluronics) and small amounts of a photoacid generator (PAG). This material system demonstrates stable liquid-like behavior in the absence of UV but undergoes bulk gelation upon UV exposure. Rheology was used to monitor the bulk properties of a series of samples undergoing UV exposure and confirm bulk gel formation. We further probe nanoparticle rearrangement using time resolved synchrotron SAXS with simultaneous UV exposure. Time dependent SAXS indicate an absence of long range order and crystallinity while changes in the scattering profile are related to short range interparticle interactions leading to a stable or arrested structure. Finally, we compare the time scales for structural rearrangement of nanoparticles with the bulk gelation beha...
Bookmarks Related papers MentionsView impact
Soft Matter, 2011
ABSTRACT In situ photorheology experiments were conducted to investigate the kinetics of UV-trigg... more ABSTRACT In situ photorheology experiments were conducted to investigate the kinetics of UV-triggered photogelation of aqueous Laponitenanoparticle dispersions formulated with less than 10 wt% of a triblock copolymer (PluronicF127) and diphenyliodonium-2-carboxylate monohydrate, a photoacid generator (PAG). We show that gelation kinetics depend strongly on solution composition and intensity of UV light used during in situ photorheology experiments. A decrease in gelation rate was observed with increasing Pluronic F127 concentrations while higher PAG and Laponite concentrations result in higher gelation rates. Changing the intensity of UV light from 100 mW cm−2 to 150 mW cm−2 at a constant composition reduced the exposure time required prior to onset of gelation by half. Finally, the effect of Laponite and PAG on the micellization of F127 was probed using differential scanning calorimetry (DSC). The results show that the presence of Laponite particles and PAG suppresses the enthalpic endotherm associated with micelle formation in solutions containing up to 7.2 wt% PluronicF127. Using these results, we present a detailed mechanism for the photogelation phenomenon as well as the parameters surrounding intelligent design and formulation of these systems.
Bookmarks Related papers MentionsView impact
Nanoscale, 2010
Bookmarks Related papers MentionsView impact
Macromolecules, 2011
Aqueous solutions of polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) triblock copo... more Aqueous solutions of polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) triblock copolymers (commercially available as Pluronic surfactants) micellize and structurally arrange into cubic quasicrystalline lattices as their temperature is raised. This structural evolution is seen macroscopically as a gelation, and the presence of these ordered phases can be controlled through both polymer concentration and temperature. The presence of added solutes within the dispersions can also
Bookmarks Related papers MentionsView impact
Advanced Functional Materials, 2010
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Advanced Functional Materials, 2010
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Acta Materialia, 2007
Using the in situ optical technique known as digital image correlation (DIC), full-field quantita... more Using the in situ optical technique known as digital image correlation (DIC), full-field quantitative strain maps of localization have been experimentally obtained for the first time in thin sheets of Nitinol. The use of DIC provides new information connecting previous observations on the micro- and macro-scales. It shows that the transformation initiates before the formation of localized bands, and the
Bookmarks Related papers MentionsView impact
Advanced Functional Materials, 2012
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact