?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F9538%2F&rft.title=Synthesis+and+Characterization+of+Poly(9%2C9-Dihexylfluorene-mb-methylene)s&rft.creator=Copenhafer%2C+James+Edward&rft.description=The+synthesis+and+characterization+of+copolymers+possessing+exact+repeating+sequences+of+9%2C9-dihexylfluorene+and+methylene+repeat+units+are+described.+Each+poly(9%2C9-dihexylfluorene-mb-methylene)+(PFM%2C+mb+%3D+multiblock)+was+synthesized+following+the+assembly+of+a+symmetrically+disubstituted+monodisperse+oligofluorene.+Alkyl+segments+possessing+terminal+alkene+functionality+were+then+coupled+at+both+of+the+substituted+positions+on+the+oligofluorene+to+give+a+macromolecular+%22segmer%22+compound.+Each+segmer+was+polymerized+using+Acyclic+Diene+Metathesis+(ADMET)+and%2C+following+post-polymerization+hydrogenation%2C+a+PFM+with+an+entirely+repeating+diblock+sequence+was+produced.+PFMs+possessing+9%2C9-dihexylfluorene+segment+lengths+of+x+%3D+1%2C+2%2C+3%2C+4%2C+7%2C+or+8+units+and+methylene+segment+lengths+of+y+%3D+10+or+18+units+were+prepared+to+give+a+ten+member+PFM+library.+As+PFMs+have+exact+chemical+compositions+and+monomer+unit+sequencing%2C+studies+aimed+at+elucidating+solution+and+bulk+phase+trends+were+performed.+Spectroscopic+characteristics+that+make+polyfluorene-type+materials+attractive+include+their+generally+efficient+blue+light+emission+(%CE%BBmax+~+448+nm).+Successful+investigations+into+the+optical+tuning+of+PFMs+in+solution+and+in+the+bulk+are+described.+Additionally%2C+thermal-+and+photostabilities+of+PFMs+under+a+variety+of+conditions+are+reported+and+compared+to+the+related+homopolymer%2C+poly(9%2C9-dihexylfluorene)+%5BPDHF%5D.+Compared+to+PDHF%2C+PFMs+display+similar%2C+and+in+some+cases+superior+resistance+to+photobleaching+processes.+Additionally%2C+thermal+and+photostability+investigations+into+keto-induced+degradation+processes+of+PFMs+suggest+that+interruption+of+the+fluorene+segments+with+alkyl+spacers+effectively+suppresses+intrachain+charge+migration+and+interchain+F%C3%B6rster+energy+transfer+in+the+bulk.+The+rate+of+PFM%2C+and+likewise+PDHF+degradation+was+found+to+be+at+least+partially+dependent+on+the+initial+state+of+the+sample.Efforts+toward+the+transition+metal-catalyzed+production+of+cyclic+oligomers+are+described.+Two+rigid+bifunctional+molecules+bearing+both+transition-metal+metathesis+initiating+and+terminating+groups+were+prepared.+The+synthesis+and+metathesis+activity+of+these+compounds+are+reported.&rft.date=2007-01-29&rft.type=University+of+Pittsburgh+ETD&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F9538%2F1%2FCopenhafer_Thesis_2006.pdf&rft.identifier=++Copenhafer%2C+James+Edward++(2007)+Synthesis+and+Characterization+of+Poly(9%2C9-Dihexylfluorene-mb-methylene)s.++Doctoral+Dissertation%2C+University+of+Pittsburgh.++++(Unpublished)++