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Your search keyword '"Johnson, Jeremiah"' showing total 173 results
Start Over Author "Johnson, Jeremiah" Publisher american chemical society
173 results on '"Johnson, Jeremiah"'

28. A magnetic switch for spin-catalyzed interconversion of nuclear spin isomers

Author

Yongjun Li, Xuegong Lei, Jockusch, Steffen, Chen, Judy Y.-C, Frunzi, Michael, Johnson, Jeremiah A., Lawler, Ronald G., Murata, Yasujiro, Murata, Michihisa, Komatsu, Koichi, and Turro, Nicholas J.

Subjects
Nuclear spin -- Analysis, Nitrogen oxide -- Magnetic properties, Hydrogen -- Magnetic properties, Chemistry
Abstract

The design of spin catalysis of the interconversion of ortho-hydrogen (o[H.sub.2]) and para-hydrogen (p[H.sub.2]) incarcerated in an endofullerene based on a reversible nitroxide/hydroxylamine system is demonstrated. The system is an example of a reversible magnetic spin catalysis switch that could increase the rate of interconversion of the nuclear spin isomers of [H.sub.2] by a factor of ~[10.sup.4].

Published
2010

29. Toward the syntheses of universal ligands for metal oxide surfaces: Controlling surface functionality through click chemistry

Author

White, Meghann A., Johnson, Jeremiah A., Koberstein, Jeffrey T., and Turro, Nicholas J.

Subjects
Ring formation (Chemistry) -- Analysis, Metallic oxides -- Structure, Metallic oxides -- Chemical properties, Transmission electron microscopes -- Observations, Ligands -- Structure, Ligands -- Properties, Chemistry
Abstract

A strategy for the synthesis of surface functionalized metal oxide nanoparticles through the design of versatile ligands such as phosphonic acid-azide and carboxylic acid-alkyne is demonstrated. The spectroscopic evidence, coupled with the TEM image showing dispersed particles, suggests that the 1,3-dipolar cycloaddition was successful and that the particles are stabilized from aggregation by the new ligand system.

Published
2006

30. Synthesis of degradable model networks via ATRP and click chemistry

Author

Johnson, Jeremiah A., Lewis, Danielle R., Diaz, David D., Finn, M.G., Koberstein, Jeffrey T., and Turro, Nicholas J.

Subjects
Ring formation (Chemistry) -- Analysis, Polymers -- Chemical properties, Polymers -- Mechanical properties, Nuclear magnetic resonance -- Usage, Chemistry
Abstract

The model networks (MNs) of different macromonomers (MAC) structures were prepared by a sequence of atom transfer radical polymerization (ATRP) from a degradable halide-containing initiator, post-polymerization transformation (PPT), and copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). It was found that the general scheme of ATRP, PPT, and CuAAC overcomes many of the inherent difficulties of MN synthesis.

Published
2006

39. Polymers at the Interface with Biology.

Author

Deming, Timothy J., Klok, Harm-Anton, Armes, Steven P., Becker, Matthew L., Champion, Julie A., Chen, Eugene Y.-X., Heilshorn, Sarah C., van Hest, Jan C. M., Irvine, Darrell J., Johnson, Jeremiah A., Kiessling, Laura L., Maynard, Heather D., de la Cruz, Monica Olvera, Sullivan, Millicent O., Tirrell, Matthew V., Anseth, Kristi S., Lecommandoux, Sebastien, Percec, Simona, Zhong, Zhiyuan, and Albertsson, Ann-Christine

Published
2018
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45. Core-Clickable PEG-Branch-Azide Bivalent-Bottle-Brush Polymers by ROMP: Grafting-Through and Clicking-To

Author

Johnson, Jeremiah A., Lu, Ying Y., Burts, Alan O., Lim, Yeon-Hee, Finn, M. G., Koberstein, Jeffrey T., Turro, Nicholas J., Tirrell, David A., and Grubbs, Robert H.

Subjects
technology, industry, and agriculture, macromolecular substances
Abstract

The combination of highly efficient polymerizations with modular "click" coupling reactions has enabled the synthesis of a wide variety of novel nanoscopic tructures. Here we demonstrate the facile synthesis of a new class of clickable, branched nanostructures, polyethylene glycol (PEG)-branch-azide bivalent-brush polymers, facilitated by "graft-through" ring-opening metathesis polymerization of a branched norbornene-PEG-chloride macromonomer followed by halide-azide exchange. The resulting bivalent-brush polymers possess azide groups at the core near a polynorbornene backbone with PEG chains extended into solution; the structure resembles a unimolecular micelle. We demonstrate copper-catalyzed azide-alkre cycloaddition (CuAAC) "click-to" coupling of a photocleavable doxorubicin (DOX)-alkyne derivative to the azide core. The CuAAC coupling was quantitative across a wide range of nanoscopic sizes (similar to 6-similar to 50 nrn); UV photolysis of the resulting DOX-loaded materials yielded free DOX that was therapeutically effective against human cancer cells.

Published
2011

46. Odd-Even Effect of Junction Functionality on the Topology and Elasticity of Polymer Networks.

Author

Rui Wang, Johnson, Jeremiah A., and Olsen, Bradley D.

Subjects
*POLYMER networks, *MONTE Carlo method, *LOOPS (Group theory), *NONMONOTONIC logic, *ELASTODYNAMICS
Abstract

The junction functionality of polymer networks is a key design variable to tune the material properties through changing the network connectivity. Here, we perform a Monte Carlo simulation to study the topology and elasticity of end-linked polymer networks constructed by junctions with different functionalities. The effect of junction functionality on the topological structure of the network displays both universal features and odd-even effects. For all junction functionalities, the primary loop fraction shows a linear dependence on the dimensionless product of concentration with single chain pervaded volume. The slopes of the lines exhibit strong odd-even alternation: primary loops are formed more frequently for junctions with an odd number of functional groups. The secondary loop fraction has a maximum when plotted against the normalized primary loop fraction, where the value of the maximum also shows odd-even alternation. The topological information obtained through Monte Carlo simulation is then incorporated into the modified affine network theory and modified phantom network theory (real elastic network theory). For affine networks, the odd-even alternation in the cyclic topology leads to nonmonotonic dependence of elastic modulus on the junction functionality. For phantom networks, the effect of decreasing junction fluctuations due to a larger number of interjunction connections dominates over the changes in loop concentration as junction functionality increases, leading to monotonically increasing elastic modulus with junction functionality. [ABSTRACT FROM AUTHOR]

Published
2017
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50. Light-Controlled Radical Polymerization: Mechanisms, Methods, and Applications.

Author

Mao Chen, Johnson, Jeremiah A., and Mingjiang Zhong

Subjects
*PHOTOPOLYMERIZATION, *ORGANIC photochemistry, *SINGLE electron transfer mechanisms, *FRAGMENTATION reactions, *PHOTOLYSIS (Chemistry)
Abstract

The use of light to mediate controlled radical polymerization has emerged as a powerful strategy for rational polymer synthesis and advanced materials fabrication. This review provides a comprehensive survey of photocontrolled, living radical polymerizations (photo-CRPs). From the perspective of mechanism, all known photo-CRPs are divided into either ( l) intramolecular photochemical processes or (2) photoredox processes. Within these mechanistic regimes, a large number of methods are summarized and further classified into subcategories based on the specific reagents, catalysts, etc., involved. To provide a clear understanding of each subcategory, reaction mechanisms are discussed. In addition, applications of photo-CRP reported so far, which include surface fabrication, particle preparation, photoresponsive gel design, and continuous flow technology, are summarized. We hope this review will not only provide informative knowledge to researchers in this field but also stimulate new ideas and applications to further advance photocontrolled reactions. [ABSTRACT FROM AUTHOR]

Published
2016
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