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    Highly Porous Acrylonitrile-Based Submicron Particles for UO22+ Absorption in an immunosensor Assay
    (Amer Chemical Soc, 2012) Şahiner, Nurettin; Yu, Haini; Tan, Grace; He, Jibao; John, Vijay T.; Blake, Diane A.
    Our laboratory has previously reported an antibody-based assay for hexavalent uranium (UO22+) that could be used on-site to rapidly assess uranium contamination in environmental water samples (Melton, S. J.; et al. Environ. Sci. Technol. 2009, 43, 6703-6709). To extend the utility of this assay to less-characterized sites of uranium contamination, we required a uranium-specific adsorbent that would rapidly remove the uranium from groundwater samples, while leaving the concentrations of other ions in the groundwater relatively unaltered. This study describes the development of hydrogel particles containing amidoxime groups that can rapidly and selectively facilitate the uptake of uranyl ions. A miniemulsion polymerization technique using SDS micelles was employed for the preparation of the hydrogel as linked submicrometer particles. In polymerization, acrylonitrile was used as the initial monomer, ethylene glycol dimethacrylate as the crosslinker and 2-hydroxymethacrylate, 1-vinyl-2-pyrrolidone, acrylic acid, or methacrylic acid were added as co-monomers after the initial seed polymerization of acrylonitrle. The particles were characterized by transmission electron spectroscopy, scanning electron microscopy (SEM) and cryo-SEM. The amidoximated particles were superior to a commercially available resin in their ability to rapidly remove dissolved UO22+ from spiked groundwater samples.
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    In situ preparation of various metal nanoparticles within hydrogel networks and their application in catalysis
    (Amer Chemical Soc, 2011) Şahiner, Nurettin; Özay, Özgür; Bütün, Sultan; Demir, Veil; Dibek, Burak; Aktaş, Nahit; He, Jibao
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    POLY 225-Acrylonitrile-based functional hydrogel particles
    (Amer Chemical Soc, 2008) Şahiner, Nurettin; Yu, Haini; Tan, Grace; He, Jibao; John, Vijay T.; Blake, Diane A.
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    The on demand generation of hydrogen from Co-Ni bimetallic nano catalyst prepared by dual use of hydrogel: As template and as reactor
    (Pergamon-Elsevier Science Ltd, 2011) Şahiner, Nurettin; Özay, Özgür; Aktaş, Nahit; Inger, Erk; He, Jibao
    We report the preparation of metal nanoparticles in various formulations inside p(2-acrylamido-2-methyl-1-propansulfonic acid; p(AMPS)) hydrogels and their utilization as a catalyst in hydrolysis of NaBH4. The swollen, flexible p(AMPS) network was used for metal ion loading and reduction in situ for the preparation of Co:Ni nanoparticles as bimetallic clusters in various formulation, and Co and Ni bimetallic catalysts as Co + Co, Co + Ni, Ni + Co and Ni + Ni. In addition to utilization of hydrogels as support materials, the p(AMPS)-metal nanoparticle system was used as catalyst to generate hydrogen in the hydrolysis of NaBH4 with very high yield. Various parameters for the hydrolysis reaction were determined and the activation parameters were calculated. For the first time, inclusion of ferrite magnetic particles to control hydrogen generation on demand by using an externally applied magnetic field to remove the hydrogel-catalyst system from the hydrolysis medium is reported. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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    Tunable Friction Through Stimuli Responsive Hybrid Carbon Microspheres
    (Amer Chemical Soc, 2019) Oak, Shreyas; Pashazanusi, Leila; Sengel, Sultan B.; Omarova, Marzhana; Hemstock, Jamie L.; He, Wei; He, Jibao
    We explore the use of poly(N-isopropylacrylamide) (PNIPAm)-grafted carbon microspheres (CM) dispersed in water as a stimulus-responsive lubricant. A critical concentration between 3 and 5 mg/mL of PNIPAm-grafted CM is needed to achieve low friction (coefficient of friction similar to 0.04) at room temperature between borosilicate and silicon surfaces. An increase in the temperature of the system above the lower critical solution temperature (LCST) causes the aggregation of PNIPAm-grafted CM which leads to an increase in friction forces. The process is not immediately reversible unless the lubricant is sonicated so as to redisperse the aggregates. This work provides insight into the rolling friction mechanism and demonstrates the importance of particle singlets in achieving effective lubrication through a rolling mechanism.