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143 results on '"Knauss, Daniel M."'

10. Synthesis and properties of cationic multiblock polyaramides and polyimides.

Author

Biery, Alison R. and Knauss, Daniel M.

Subjects
POLYIMIDES, APROTIC solvents, COPOLYMERS, POLAR solvents, OLIGOMERS, MOIETIES (Chemistry)
Abstract

Poly(diallyldimethylammonium chloride) (PDADMAC) is a useful material due to its high charge density and alkaline stability, but its hydrophilic nature limits applications to those where the dissolved polymer is appropriate. To make polymers suitable for applications as films and membranes containing the diallyldimethylammonium moiety, multiblock copolymers of polyaramides (PA) and polyimides (PI), materials known for their excellent physical properties and stabilities, were synthesized. Aminophenyl difunctionalized PDADMAC oligomers were synthesized using a disulfide iniferter then counterion exchanged to the hexafluorophosphate anion to produce telechelic oligomers with good solubility in polar aprotic solvents. The oligomers were reacted in situ with the proper difunctional monomers to produce PA, polyetheraramides, PI, and polyetherimides. All the classes of copolymers were synthesized over a range of compositions at high yield and material properties were demonstrated to be a result of both the backbone chemistry and the composition. Several of the synthesized copolymers formed films with good clarity, strength, and flexibility. The copolymers containing ether linkages had increased backbone flexibility and demonstrated better film‐forming properties. The multiblock copolyaramides and copolyimides demonstrate a method to produce materials with excellent thermal stability and good strength and flexibility, making them uniquely capable of serving as water insoluble, cationic films, and membranes. [ABSTRACT FROM AUTHOR]

Published
2023
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16. Designing Alkaline Exchange Membranes from Scratch

Author

Sarode, Himanshu, primary, Vandiver, Melissa A., additional, Maes, Ashley M., additional, Caire, Benjamin, additional, Horan, James L., additional, Yan, Yating, additional, Li, Yifan, additional, Lindberg, Gerrick E., additional, Dama, James F., additional, Knight, Chris, additional, Jorn, Ryan, additional, Lenz, Martin E., additional, Kasper, Robert, additional, Gu, Shuang, additional, Zhang, Bingzi, additional, Seifert, Sönke, additional, Tsai, Tsung-han, additional, Zhang, Wen X., additional, Coughlin, E. Bryan, additional, Knauss, Daniel M., additional, Yan, Yushan, additional, Voth, Gregory A., additional, Witten, Thomas A., additional, Liberatore, Matthew W., additional, and Herring, Andrew M., additional

Published
2019
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28. A Highly Hydroxide Conductive, Chemically Stable Anion Exchange Membrane, Poly(2,6 dimethyl 1,4 phenylene oxide)-b-Poly(vinyl benzyl trimethyl ammonium), for Electrochemical Applications

Author

Pandey, Tara P., primary, Sarode, Himanshu N., additional, Yang, Yating, additional, Yang, Yuan, additional, Vezzù, Keti, additional, Noto, Vito Di, additional, Seifert, Soenke, additional, Knauss, Daniel M., additional, Liberatore, Matthew W., additional, and Herring, Andrew M., additional

Published
2016
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30. Sequential Bulk Anionic Polymerization of α-Methylstyrene and Isoprene to Form Diblock and Triblock Copolymers.

Author

Li, Yifan and Knauss, Daniel M.

Subjects
*DIBLOCK copolymers, *ADDITION polymerization, *STYRENE, *REACTIVITY (Chemistry), *MOLECULAR weights, *MICROSTRUCTURE
Abstract

α-Methylstyrene (AMS) is determined to polymerize anionically by initiation with sec-bultyllithium under bulk conditions with control of molecular weight depending on reaction time. Furthermore, the reactivity between AMS and isoprene in a mixture at a high AMS concentration (90% v/v) indicates a strong inclination for almost sole isoprene polymerization (>97%). The microstructure of the polyisoprene is determined to be predominately 1,4-polyisoprene in the bulk AMS polymerization. These results afford a sequential process for the formation of diblock and triblock copolymers whereby the anionic initiation of AMS in the bulk produces a living poly(α-methylstyrene) (PAMS) that upon addition of isoprene results in a living PAMS- b-polyisoprene (PAMS- b-PI). Triblock copolymer can be prepared by adding N, N, N′, N′-tetramethylethylenediamine to increase the crossover reaction to reinitiate AMS from the living diblock and form PAMS- b-PI- b-PAMS. Gel permeation chromatography, 1H NMR spectroscopy, differential scanning calorimetry, and thermal gravimetric analysis are used to characterize the products. [ABSTRACT FROM AUTHOR]

Published
2018
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35. 2014 Faculty Conference: faculty senate overview

Author

Knauss, Daniel M.

Subjects
faculty conference, senate, strategic plan, faculty survey
Abstract

This presentation provides an overview of faculty senate objectives, presents an organization chart showing how the senate interacts with other committees, lists the 2014/2015 senators, notes the previous year's activities, and outlines ongoing initiatives and goals.

Published
2007
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38. (Invited) Thin Robust Anion Exchange Membranes for Fuel Cell Applications

Author

Sarode, Himanshu N, primary, Vandiver, Melissa A, additional, Liu, Ye, additional, Maes, Ashley, additional, Pandey, Tara Prasad, additional, Ertem, S Piril, additional, Tsai, Tsunghan, additional, Zhang, Bingzi, additional, Herbst, Daniel, additional, Linberg, Gerrick, additional, Tse, Ying-Lung Steve, additional, Seifert, Sönke, additional, Di Noto, Vito, additional, Coughlin, E. Bryan, additional, Yan, Yushan, additional, Voth, Gregory, additional, Witten, Thomas, additional, Knauss, Daniel M, additional, Liberatore, Matthew W, additional, and Herring, Andrew M, additional

Published
2014
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39. Thin Robust Anion Exchange Membranes for Fuel Cell Applications

Author

Sarode, Himanshu N, primary, Vandiver, Melissa A, additional, Liu, Ye, additional, Maes, Ashley, additional, Pandey, Tara Prasad, additional, Ertem, S Piril, additional, Tsai, Tsunghan, additional, Zhang, Bingzi, additional, Herbst, Daniel, additional, Linberg, Gerrick, additional, Tse, Ying-Lung Steve, additional, Seifert, Sönke, additional, Di Noto, Vito, additional, Coughlin, E. Bryan, additional, Yan, Yushan, additional, Voth, Gregory, additional, Witten, Thomas, additional, Knauss, Daniel M, additional, Liberatore, Matthew W, additional, and Herring, Andrew M, additional

Published
2014
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41. Progress towards Robust Anion Exchange Membranes for Fuel Cell Applications

Author

Sarode, Himanshu, primary, Vandiver, Melissa, additional, Caire, Benjamin, additional, Liu, Ye, additional, Horan, James L, additional, Yang, Yating, additional, Li, Yifan, additional, Herbst, Daniel, additional, Lindberg, Gerrick E., additional, Tse, Ying-Lung Steve, additional, Seifert, Sönke, additional, Coughlin, E. Bryan, additional, Knauss, Daniel M, additional, Yan, Yushan, additional, Voth, Gregory, additional, Witten, Thomas, additional, Liberatorre, Mathew, additional, and Herring, Andrew M, additional

Published
2013
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44. Sulfonated poly( meta-phenylene isophthalamide)s as proton exchange membranes.

Author

Liu, Feilong and Knauss, Daniel M.

Subjects
*POLYMERS, *POLYMERIZATION, *FUNCTIONAL groups, *MOLECULAR structure, *CHEMICAL reactions
Abstract

ABSTRACT Random and block sulfonated poly( meta-phenylene isopthalamide)s as proton exchange membranes were synthesized through the Higashi-Yamazaki phosphorylation method. Polymers with different degrees of sulfonation from 40 to 100 mol percent were prepared by adjusting the molar feed ratio of 5-sulfoisophthalic acid sodium salt (SIPA) and isophthalic acid (IPA) in the reaction with meta-phenylene diamine. Creasable polymer films were obtained by casting DMSO polymer solutions and the membrane films could be exchanged to the proton form in strong acid. 1H NMR spectroscopy and titration confirmed the degree of sulfonation. Thermogravimetric analysis demonstrated good thermal stabilities with 5% weight loss greater than 380 °C. The copolymers with low degrees of sulfonation (DS = 40 mol %) exhibited low water uptake (water uptake < 17 wt %) at room temperature. A segmented multiblock copolymer prepared by preforming a sulfonated block showed lower water uptake at high temperatures than the random polymer with the same DS of 40 mol % and displayed stability in water up to 80 °C. Both random and block copolymers showed higher proton conductivities at high temperature than that of Nafion-117 under 95% relative humidity. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2582-2592 [ABSTRACT FROM AUTHOR]

Published
2016
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49. Synthesis and characterization of new polycarbonate material systems

Author

Knauss, Daniel M., Chemistry, McGrath, James E., Gibson, Harry W., Wilkes, Garth L., Riffle, Judy S., and Shultz, Allan R.

Subjects
LD5655.V856 1994.K627, Polycarbonates
Abstract

Bisphenol A polycarbonate is an engineering thermosplastic which can be utilized for a variety of applications. Modifications to improve upon the properties of this useful material have been attempted since its invention. Three modifications of bisphenol A polycarbonate and its copolymers have been examined in this work. The hydrolytic stability of copolymers of polydimethylsiloxane and polycarbonate was improved by the synthesis of pre-formed phenol functional polydimethylsiloxane oligomers in which the Si is attached directly to the aromatic ring of the hydroxyaryl functional component. In situ random block copolymers of polydimethylsiloxane and polycarbonate were synthesized by interfacial polymerization techniques. The Si-aryl bonds of the novel polydimethylsiloxane oligomers were found to impart good thermal and hydrolytiC stability to the random block copolymers. Terminally reactive polycarbonate oligomers were also synthesized in order to form polycarbonate network materials. 4-Acetoxystyrene was utilized as a stable precursor to 4-vinylphenol which could then be used to quantitatvely control the molecular weight and functionality of the polycarbonate chains. The reactive oligomers were found to undergo a thermal cure above the respective glass transition temperatures to form insoluble networks. These network materials were found to have superior solvent resistance as compared to the linear material while retaining much of the useful mechanical properties (high fracture toughness, etc.) of bisphenol A polycarbonate. Furthermore, the glass transition temperatures of the networks were found to increase with a decrease in the molecular weight between crosslinks. The fire resistance properties of polycarbonate were modified by the copolymerization of bisphenol A with phenol derivatives of triphenylphosphine oxide. The effect of changes in the composition were determined by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature, as well as the residual char yield at elevated temperatures was found to increase with an increase in the phosphorus monomer content as measured by the two respective methods. Cone calorimetry was also performed on the samples to determine the heat release rate, which reflected an increase in the fire resistance properties with an increase in the phosphorus content. Ph. D.

Published
1994

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