ZWITTERION POLYMERIZATION OF 2-METHYL-2-OXAZOLINE AND ACRYLIC ACID.
Item
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Title
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ZWITTERION POLYMERIZATION OF 2-METHYL-2-OXAZOLINE AND ACRYLIC ACID.
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Identifier
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AAI8401902
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identifier
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8401902
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Creator
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GUNATILLAKE, PATHIRAJA A.
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Contributor
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George Odian
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Date
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1983
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Polymer
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Abstract
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The zwitterion polymerization of 2-methyl-2-oxazoline(MeOXO) and acrylic acid (AA) has been investigated in bulk and solution (DMF and acetonitrile) at 60-70(DEGREES)C. Variation of reaction conditions such as temperature, methods of monomer addition, high vacuum conditions to avoid adventitious terminating agents, solvents, and addition of a nucleophile to the reaction system resulted in copolymers having number average molecular weights in the range 590-2760 as determined by vapor pressure osmometry. Three stage polymerization showed that the MeOXO-AA monomer system does not behave as one with living characteristics. The copolymer composition was established as 1:1 (MeOXO:AA) by proton NMR. Proton and ('13)C NMR spectroscopy identified the repeating unit as -CH(,2)CH(,2)N(COCH(,3))CH(,2)CH(,2)COO- and the end groups as olefinic(CH(,2)=CHCOO-), carboxyl(-COOH) and acetamido (-NHCOCH(,3)). Infrared spectroscopy supports the NMR results. Hydrolysis experiments corroborated both the copolymer composition and identity of the end groups. N-(2-hydroxyethyl)-(beta)-alanine (from the repeating unit) was isolated from the hydrolysis products of the copolymer. Presence of acrylic acid (from the olefinic end group) and acetic acid (from the repeating unit) among hydrolysis products was confirmed by GC and analytical HPLC. Presence of ethanolamine (from the acetamido end group) was confirmed by isolating it as the dibenzoyl derivative. High performance liquid chromatography showed that the copolymer product consists of different-sized molecules and not all molecules have the same two end groups. Some molecules had olefinic and carboxyl end groups and the others olefinic and acetamido end groups. A mechanism is proposed to describe the MeOXO-AA polymerization. MeOXO and AA forms a genetic zwitterion which is responsible for initiation. Polymer growth involves various-sized zwitterions reacting with each other and with the genetic zwitterion by a ring opening attack of carboxylate anion on the quaternery MeOXO ring. Termination occurs by reaction of growing zwitterions both with acrylic acid and with a quaternized MeOXO-acrylate salt (formed by proton transfer between MeOXO-AA). Direct NMR analysis of the polymerizing MeOXO-AA system gave evidence for the genetic zwitterion and early termination of growing zwitterions by reaction with quaternized MeOXO-acrylate salt.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
