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dc.contributor.authorTrenor, Scott Russellen_US
dc.date.accessioned2014-03-14T20:10:55Z
dc.date.available2014-03-14T20:10:55Z
dc.date.issued2004-04-16en_US
dc.identifier.otheretd-04262004-150913en_US
dc.identifier.urihttp://hdl.handle.net/10919/27314
dc.description.abstractCoumarin and cinnamate derivatives were positioned as either polymer chain ends or side groups to synthesize photoactive macromolecules and gain the ability to reversibly control molecular weight and crosslink density using UV light. The cinnamates and coumarins were reacted onto the polymers via multiple reaction pathways. Polymers were functionalized with coumarin or cinnamate groups via an esterification reaction between hydroxyl functionalities and an acid chloride derivatized coumarin group. In addition to the esterification reaction, cinnamates were also coupled to polymers via a ring opening reaction between a hydroxyl functionalized cinnamate derivative and a maleic anhydride repeat unit copolymerized into the polymer. Both functional groups undergo a [2p + 2p] photodimerization reaction (coumarin groups in the UVA and cinnamate groups in the UVB), which was utilized to crosslink and chain-extend macromolecules. Coumarin dimers possess the additional ability to photocleave and thus reverse when irradiated at 254 nm. The coumarin reversible photodimerization reaction was utilized to reversibly increase the molecular weight and molecular weight distribution of coumarin-functionalized PEG monols and diols. For example, the number average molecular weight of the coumarin-functionalized PEG diol doubled and the molecular weight distribution increased from 1.08 to 2.75 when exposed to 110 J cm-2 of UVA irradiation. Subsequent photocleavage (UVC irradiation, 2 J cm-2) of the chain-extended PEGs, cleaved coumarin dimers decreasing the molecular weight and molecular weight distribution to their original values. A number of poly(alkyl acrylate) and poly(methyl acrylate) systems were functionalized with coumarin groups to study the effect of the glass transition temperature and alkyl ester side group composition on the photodimerization reaction and subsequent crosslinking. The glass transition temperature (Tg) acted as an on/off switch for the photodimerization reaction. While the absolute difference between Tg and irradiance temperature did not affect the rate or extent of photodimerization reaction, polymers with a Tg greater than the irradiance temperature displayed less reaction than those with a Tg lower than the irradiance temperature. The final extent of conversion was controlled by a complex combination of factors including alkyl ester side chain steric bulkiness. Coumarin-functionalized alkyl acrylates based on ethylhexyl acrylate were tested as detachable PSAs. A 98% decrease in the adhesive peel strength was observed after exposure to UVA irradiation. Cinnamate groups were utilized in the design and synthesis of UV-curable hot melt pressure sensitive adhesives (PSAs). The cinnamate groups were attached to the PSAs to provide a method to increase molecular weight and add a small amount of crosslinking leading to an increase the adhesive strength of the PSAs. Broadband UV irradiation from a laboratory scale industrial lamp increased the peel strength of the adhesives. Postcure of the irradiated cinnamate-functionalized UV-curable hot melt PSAs was reduced compared to photoinitiated free-radical photocurable UV-curable hot melt PSAs.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartScottRTrenorDissertation.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectCoumarinen_US
dc.subjectPolymer Photochemistryen_US
dc.subjectAdhesivesen_US
dc.subjectAlkyl Acrylatesen_US
dc.subjectCinnamatesen_US
dc.titleSynthesis and Characterization of Tailored Photoactive Macromoleculesen_US
dc.typeDissertationen_US
dc.contributor.departmentMacromolecular Science and Engineeringen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineMacromolecular Science and Engineeringen_US
dc.contributor.committeememberDillard, David A.en_US
dc.contributor.committeememberWard, Thomas C.en_US
dc.contributor.committeememberRiffle, Judy S.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-04262004-150913/en_US
dc.contributor.committeecochairLove, Brian J.en_US
dc.contributor.committeecochairLong, Timothy E.en_US
dc.date.sdate2004-04-26en_US
dc.date.rdate2005-04-27
dc.date.adate2004-04-27en_US


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