Synthesis and characterization of high performance polybenzoxazoles

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dc.contributor.authorJoseph, William Daleen
dc.contributor.committeechairMcGrath, James E.en
dc.contributor.committeememberWard, Thomas C.en
dc.contributor.committeememberGibson, Harry W.en
dc.contributor.committeememberRiffle, Judy S.en
dc.contributor.committeememberTanko, James M.en
dc.contributor.departmentChemistryen
dc.date.accessioned2014-03-14T21:09:07Zen
dc.date.adate2007-02-02en
dc.date.available2014-03-14T21:09:07Zen
dc.date.issued1993-08-05en
dc.date.rdate2007-02-02en
dc.date.sdate2007-02-02en
dc.description.abstractHigh molecular weight poly(hydroxy amide)s and polybenzoxazoles possessing a variety of backbone compositions have been synthesized via low temperature polycondensation and a novel catalytic cyclization reaction. Preliminary experiments involved the synthesis of poly(hydroxy amide)s and polybenzoxazoles based on a bisphenol-A aminophenol and isomeric acid chlorides. The polymers exhibited T<sub>g</sub>'s around 280°C, limited solubilities and only fair thermo-oxidative stabilities. In an effort to improve these properties. fluorinated monomers were investigated. A number of novel fluorinated monomers and commercial monomers were incorporated into poly(hydroxy amide)s and polybenzoxazoles using the above mentioned polymerization/cyclization techniques. Enhanced solubilities, glass transition temperatures and thermooxidative stabilities were realized. Difficulties encountered during the polymerization of the fluorinated monomers prompted the study of polymerization conditions. Results of these studies indicate that the electronic environment about the bis(o-aminophenol)s and acid chlorides dictates the ability of these monomers to participate in an ester forming side reaction. Physical and spectroscopic evidence was presented to support this conclusion. Investigations were also conducted to determine optimum cyclization conditions. It was shown that pyridine hydrochloride and p-toluenesulfonic acid monohydrate were active cyclization catalysts when used in conjunction with an azeotroping solvent, such as toluene or 0- dichlorobenzene. In general, complete cyclization of the oxazole rings could be achieved in as little as 6 hours at 175°C. Unfortunately, generic cyclization conditions were not found. Additionally, phenylethynyl terminated polybenzoxazoles were successfully synthesized using the above techniques. Molecular weight control and phenylethynyl incorporation were confirmed by spectroscopic, thermal and mechanical analyses.en
dc.description.degreePh. D.en
dc.format.extentxxiii, 342 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-02022007-133644en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-02022007-133644/en
dc.identifier.urihttp://hdl.handle.net/10919/37281en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1993.J677.pdfen
dc.relation.isformatofOCLC# 30659083en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V856 1993.J677en
dc.subject.lcshPolymerizationen
dc.subject.lcshPolymersen
dc.titleSynthesis and characterization of high performance polybenzoxazolesen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineChemistryen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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