Julia King - Profile on Academia.edu (original) (raw)
Papers by Julia King
Effect of low temperature gel aging on zeolite LTA particle size and morphology in template-free hydrogel process
Levofloxacin impregnation and extended release: Concentration model for insulin catheters
Biomedical Engineering Advances
Coarsening and Spinodal Decomposition of Zeolite Linde Type A Precursor Gels Aged at Low Temperatures
Crystal Growth & Design, 2016
We monitored the effect of different gel aging temperatures (from −20 to 40 °C) and gel aging tim... more We monitored the effect of different gel aging temperatures (from −20 to 40 °C) and gel aging times (from 7 to 21 days) on the particle size and crystalline structure of template-free Linde type A zeolites through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. We demonstrate the synthesis of zeolite LTA with average particle sizes of 0.45 ± 0.07 μm by preliminary heat treatment of the precursor gel at −8 °C followed by crystallization at 100 °C. Here, we found that aging the precursor gels for 2 weeks at 40 °C decreases the size of particles by 59% compared with particles formed from unaged gels, and aging gels for 2 weeks at −8 °C results in particles that have a 95% smaller diameter compared with particles formed from the unaged gel. We hypothesize that decreasing the precursor aging temperature below 0 °C leads to the occurrence of spinodal decomposition at which the nucleation barrier vanishes. Consequently, a very large number of nuclei form...
Langmuir, 2014
Here we present the formation of thin layers of barrier polymers onto mesoporous and macroporous ... more Here we present the formation of thin layers of barrier polymers onto mesoporous and macroporous substrates via dip coating of latex solutions. We investigated four commercially available latex solutions: polytetrafluoroethylene (PTFE), perfluoroalkoxy fluorothermoplastic (PFA), polyvinylidene chloride (PVDC), and polyolefin-based latex (Hypod). We examined the latex film formation on porous polymeric and ceramic substrates with a broad range of pore sizes from 10 to 200 nm. Our results show that both characteristics of the latex solution [glass transition temperature (T g ), particle size, and crystallinity] and the characteristics of the porous substrate (pore size and hydrophobicity) impact the film formation. We confirmed the defect-free, barrier nature of our latex thin films through scanning electron microscopy (SEM), atomic force microscopy (AFM), and hydraulically driven water permeation tests. Additionally, we found that latex concentration (not dipping time) is the most important parameter determining ultimate latex film thickness. We obtained defect-free films from PVDC and Hypod, which are "soft" polymers (T g < room temperature), on mesoporous substrates under the conditions of slow evaporation rate of the solvent from these latex solutions. PTFE and PFA, which are "hard" polymers (T g > room temperature), did not form continuous films on porous substrates.
Effect of low temperature gel aging on zeolite LTA particle size and morphology in template-free hydrogel process
Levofloxacin impregnation and extended release: Concentration model for insulin catheters
Biomedical Engineering Advances
Coarsening and Spinodal Decomposition of Zeolite Linde Type A Precursor Gels Aged at Low Temperatures
Crystal Growth & Design, 2016
We monitored the effect of different gel aging temperatures (from −20 to 40 °C) and gel aging tim... more We monitored the effect of different gel aging temperatures (from −20 to 40 °C) and gel aging times (from 7 to 21 days) on the particle size and crystalline structure of template-free Linde type A zeolites through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. We demonstrate the synthesis of zeolite LTA with average particle sizes of 0.45 ± 0.07 μm by preliminary heat treatment of the precursor gel at −8 °C followed by crystallization at 100 °C. Here, we found that aging the precursor gels for 2 weeks at 40 °C decreases the size of particles by 59% compared with particles formed from unaged gels, and aging gels for 2 weeks at −8 °C results in particles that have a 95% smaller diameter compared with particles formed from the unaged gel. We hypothesize that decreasing the precursor aging temperature below 0 °C leads to the occurrence of spinodal decomposition at which the nucleation barrier vanishes. Consequently, a very large number of nuclei form...
Langmuir, 2014
Here we present the formation of thin layers of barrier polymers onto mesoporous and macroporous ... more Here we present the formation of thin layers of barrier polymers onto mesoporous and macroporous substrates via dip coating of latex solutions. We investigated four commercially available latex solutions: polytetrafluoroethylene (PTFE), perfluoroalkoxy fluorothermoplastic (PFA), polyvinylidene chloride (PVDC), and polyolefin-based latex (Hypod). We examined the latex film formation on porous polymeric and ceramic substrates with a broad range of pore sizes from 10 to 200 nm. Our results show that both characteristics of the latex solution [glass transition temperature (T g ), particle size, and crystallinity] and the characteristics of the porous substrate (pore size and hydrophobicity) impact the film formation. We confirmed the defect-free, barrier nature of our latex thin films through scanning electron microscopy (SEM), atomic force microscopy (AFM), and hydraulically driven water permeation tests. Additionally, we found that latex concentration (not dipping time) is the most important parameter determining ultimate latex film thickness. We obtained defect-free films from PVDC and Hypod, which are "soft" polymers (T g < room temperature), on mesoporous substrates under the conditions of slow evaporation rate of the solvent from these latex solutions. PTFE and PFA, which are "hard" polymers (T g > room temperature), did not form continuous films on porous substrates.