Toward Optimization of Photomodulation of Azobenzene-modified PPV Derivatives

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dc.contributor.advisorEnglish, Douglas Sen_US
dc.contributor.authorGrimes, Amy Francesen_US
dc.contributor.departmentChemistryen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2008-04-22T16:01:46Z
dc.date.available2008-04-22T16:01:46Z
dc.date.issued2007-10-01en_US
dc.description.abstractPhotophysical characterization of a family of photoswitchable conjugated polymers is presented in this work. Additionally the instrumentation constructed for these studies, a time-correlated single photon counting spectrometer, is discussed along with the methods used to characterize the instrument. Sample data and fitting procedures are presented. Overall instrument capabilities are also presented, specifically the use of the spectrometer to measure time-resolved fluorescence anisotropy. An example study probing the interactions between charged fluorophores and surfactant vesicles is included as a demonstration of a time-resolved fluorescence anisotropy application. Understanding the effect of side chain modifications on the emission of light from conjugated polymers is useful in the design of new polymers for applications in sensing and photovoltaics. This thesis focuses on determining the photophysical interactions between a photochromic side chain, azobenzene, covalently bound to a poly(p-phenylenevinylene) (PPV) derivative. Time-resolved and steady-state fluorescence measurements were employed in these studies. The photochromic azobenzene quenches emission from the PPV backbone differentially in its' two isomeric states. Both static quenching and non-radiative energy transfer were found to play important roles in the differential quenching of PPV emission by azobenzene. These studies led to the definition of a parameter to judge degree of difference in quenching between the two isomeric forms. This parameter, modulation efficiency (Emod), serves throughout the studies as an important figure of merit for the depth of modulation observed for structurally modified derivatives of the original azobenzene-modified PPV derivative. Maximizing the modulation efficiency was the aim of the PPV studies. The results presented here elucidated the complex photophysical processes that influence the emission properties of this family of azobenzene-modified PPV derivatives. Important guidelines to maximize modulation efficiency were determined based on these results which will aid researchers in the design of photomodulated conjugated polymers.en_US
dc.format.extent1751485 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/7607
dc.language.isoen_US
dc.subject.pqcontrolledChemistry, Physicalen_US
dc.subject.pqcontrolledChemistry, Polymeren_US
dc.subject.pquncontrolledPPVen_US
dc.subject.pquncontrolledazobenzeneen_US
dc.subject.pquncontrolledconjugated polymersen_US
dc.subject.pquncontrolledphotoswitchen_US
dc.subject.pquncontrolledenergy transferen_US
dc.subject.pquncontrolledTCSPCen_US
dc.titleToward Optimization of Photomodulation of Azobenzene-modified PPV Derivativesen_US
dc.typeDissertationen_US

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