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Synthesis and characterization of po...

Johnson, Frederick Edward.

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Synthesis and characterization of polybenzimidazole based polyphosphonates and polyphosphonic acids.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Synthesis and characterization of polybenzimidazole based polyphosphonates and polyphosphonic acids./
Author:	Johnson, Frederick Edward.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2007,
Description:	365 p.
Notes:	Source: Dissertations Abstracts International, Volume: 69-10, Section: B.
Contained By:	Dissertations Abstracts International69-10B.
Subject:	Polymer chemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3291257
ISBN:	9780549360384

Synthesis and characterization of polybenzimidazole based polyphosphonates and polyphosphonic acids.
Johnson, Frederick Edward.

Synthesis and characterization of polybenzimidazole based polyphosphonates and polyphosphonic acids. - Ann Arbor : ProQuest Dissertations & Theses, 2007 - 365 p.

Source: Dissertations Abstracts International, Volume: 69-10, Section: B.

Thesis (Ph.D.)--State University of New York College of Environmental Science and Forestry, 2007.

This item must not be sold to any third party vendors.

Novel polyphosphonate esters and polyphosphonic acids based on poly[2,2'-(- m-phenylene-)-5,5'-bibenzimidazole] (PBI) have been synthesized by reaction with diethyl phosphonyl radicals. Our findings support a free radical mechanism in which phosphorus based radicals add to the aromatic backbone, followed by restoration of aromaticity by a second radical specie. Low molecular weight aromatic compounds have already been phosphonylated through similar chemistry. PBI diethyl phosphonates (PBIPEt) are obtained in which the phosphonate ester groups are attached directly to the aromatic backbone through stable C-P bonds. Degrees of substitution (DS) as high as 3, or three diethyl phosphonyl groups per PBI repeat unit, may be prepared. Treatment of the PBIPEts with hot aqueous acid yields the corresponding PBI phosphonic acids (PBIPOH). Advantages of this synthetic approach include: high degrees of substitution and hence high ion charge densities possible, exclusion of aliphatic moieties which could compromise thermal stability and only one synthetic step is required for the formation of phosphonate esters. PBIPEts with high degrees of substitution are soluble in methanol and ethanol due to the ability of the P=O moiety to form a hydrogen bond. The PBI phosphonic acids are soluble in aqueous sodium hydroxide and proton conducting membranes are readily formed by casting such solutions followed by immersion in aqueous acid. In free acid form, PBIPOH membranes with high ICDs are water insoluble, thermally stable, display high ionic conductivity and therefore show promise for use in electrochemical cells. The phosphonylation reaction employed for synthesis of PBIPEt was also carried out on the model compounds benzimidazole and 2,2'-diphenyl-5,5'-bibenzimidazole (DPB). Diethyl phosphonyl derivatives of both model compounds as well as N-alkyl derivatives of benzimidazole were synthesized in order to expedite structural characterization of the polymers as well as mechanistic study of the phosphonylation reaction.

ISBN: 9780549360384Subjects--Topical Terms:

3173488
Polymer chemistry.

Synthesis and characterization of polybenzimidazole based polyphosphonates and polyphosphonic acids.
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100 1 $a Johnson, Frederick Edward. $3 3433784
245 1 0 $a Synthesis and characterization of polybenzimidazole based polyphosphonates and polyphosphonic acids.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2007
300 $a 365 p.
500 $a Source: Dissertations Abstracts International, Volume: 69-10, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Cabasso, Israel.
502 $a Thesis (Ph.D.)--State University of New York College of Environmental Science and Forestry, 2007.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a Novel polyphosphonate esters and polyphosphonic acids based on poly[2,2'-(- m-phenylene-)-5,5'-bibenzimidazole] (PBI) have been synthesized by reaction with diethyl phosphonyl radicals. Our findings support a free radical mechanism in which phosphorus based radicals add to the aromatic backbone, followed by restoration of aromaticity by a second radical specie. Low molecular weight aromatic compounds have already been phosphonylated through similar chemistry. PBI diethyl phosphonates (PBIPEt) are obtained in which the phosphonate ester groups are attached directly to the aromatic backbone through stable C-P bonds. Degrees of substitution (DS) as high as 3, or three diethyl phosphonyl groups per PBI repeat unit, may be prepared. Treatment of the PBIPEts with hot aqueous acid yields the corresponding PBI phosphonic acids (PBIPOH). Advantages of this synthetic approach include: high degrees of substitution and hence high ion charge densities possible, exclusion of aliphatic moieties which could compromise thermal stability and only one synthetic step is required for the formation of phosphonate esters. PBIPEts with high degrees of substitution are soluble in methanol and ethanol due to the ability of the P=O moiety to form a hydrogen bond. The PBI phosphonic acids are soluble in aqueous sodium hydroxide and proton conducting membranes are readily formed by casting such solutions followed by immersion in aqueous acid. In free acid form, PBIPOH membranes with high ICDs are water insoluble, thermally stable, display high ionic conductivity and therefore show promise for use in electrochemical cells. The phosphonylation reaction employed for synthesis of PBIPEt was also carried out on the model compounds benzimidazole and 2,2'-diphenyl-5,5'-bibenzimidazole (DPB). Diethyl phosphonyl derivatives of both model compounds as well as N-alkyl derivatives of benzimidazole were synthesized in order to expedite structural characterization of the polymers as well as mechanistic study of the phosphonylation reaction.
590 $a School code: 0213.
650 4 $a Polymer chemistry. $3 3173488
690 $a 0495
710 2 $a State University of New York College of Environmental Science and Forestry. $b Environmental & Forest Chemistry. $3 3433785
773 0 $t Dissertations Abstracts International $g 69-10B.
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791 $a Ph.D.
792 $a 2007
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3291257