?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%2F37050%2F&rft.title=The+Importance+of+Minor+Sequence+Alterations+on+the+Hydrolysis+Behaviors+of+Degradable+Polyesters&rft.creator=Nowalk%2C+Jamie+A.&rft.description=The+extent+to+which+small+changes+in+monomer+sequence+affect+the+behaviors+of+biological+macromolecules+is+studied+regularly%2C+yet+the+dependence+of+bulk+properties+on+small+sequence+alterations+is+underexplored+for+synthetic+copolymers.++Investigations+of+this+type+are+limited+by+the+arduous+syntheses+required%2C+lack+of+scalability%2C+and+scarcity+of+examples+of+polymer+systems+that+are+known+to+exhibit+sensitive+sequence%2Fproperty+dependencies.+Our+group+has+previously+explored+the+hydrolysis+behaviors+of+a+library+of+sequenced+poly-(lactic-co-glycolic+acid)s+(PLGAs)+and+found+a+strong+correlation+with+the+L-G+sequence.+To+investigate+the+degree+to+which+properties+are+dominated+in+this+system+by+relatively+minor+sequence+changes%2C+L-G+sequences+were+incorporated+into+cyclic+macromonomers%2C+and+these+macromonomers+were+subjected+to+entropy-driven+ring-opening+metathesis+polymerization.+This+polymerization+method+produces+polymers+with+molecular+weight+control+and+sequence+preservation%2C+both+being+required+for+studies+in+which+subtle+sequence+changes+are+compared.%0D%0ATwo+hydrolysis+studies+were+performed+in+which+a+precisely+sequenced+polymer+containing+a+base+alternating+sequenced+segment%2C+LGLGL%2C+was+compared+against+1)+a+copolymer+in+which+the+LGLGL+segment+was+randomized%2C+i.e.%2C+L3G2%2C+thus+confining+disorder+within+this+short+segment%2C+and+2)+the+base+sequence+doped+with+varying%2C+small+quantities+of+LGGGL+%E2%80%9Cerror%E2%80%9D+segments.+In+this+first+hydrolysis+study%2C+molecular+weight+decrease%2C+mass+loss%2C+thermal+behaviors%2C+and+film%2Fsurface+characteristics+were+monitored+to+reveal+stark+differences+in+degradation+behaviors+despite+the+confinement+of+errors+within+a+short+segment.+In+the+second+hydrolysis+study%2C+degradation+rate+proved+tolerant+to+substitutions+up+to+1%25+of+the+monomers+but+accelerated+significantly+when+the+error+population+was+larger.%0D%0AIn+instances+where+copolymer+properties+are+dependent+on+monomer+order%2C+sequence+engineering+expands+the+functional+capabilities+of+a+given+set+of+monomers.+Investigations+of+how+localized%2C+property-dominating+sequence+segments+affect+behavior+may+aid+researchers+in+establishing+synthetic+methods+to+either+incorporate+or+eliminate+such+sequences+for+the+preparation+of+materials+for+advanced+function.&rft.date=2019-09-27&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%2F37050%2F1%2FThesis_Jamie%2520Nowalk_7.26.19_Fixed.pdf&rft.identifier=++Nowalk%2C+Jamie+A.++(2019)+The+Importance+of+Minor+Sequence+Alterations+on+the+Hydrolysis+Behaviors+of+Degradable+Polyesters.++Doctoral+Dissertation%2C+University+of+Pittsburgh.++++(Unpublished)++