?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%2F6386%2F&rft.title=Teflon+AF+membrane+transport+of+organic+solutes&rft.creator=Zhang%2C+Jie&rft.description=Teflon+AF+2400+membranes+containing+various+weight+percent+FC-70+were+cast+from+FC-72+solution.+The+membrane+surface+is+hydrophobic+as+shown+by+contact+angle+measurement.+Free+volume+in+Teflon+membranes+was+calculated+by+measuring+the+membrane+density+using+the+hydrostatic+method.+Differential+scanning+calorimetry+(DSC)+and+thermomechanical+analysis+(TMA)+were+conducted+to+study+the+thermal+transitions+of+Teflon+AF+membranes.+The+glass+transition+temperature+of+Teflon+membranes+is+-63+%C2%A1%C3%A3C+at+5+wt%25+FC-70+in+comparison+with+240+%C2%A1%C3%A3C+at+0+wt%25+FC-70.+The+permeability+of+Teflon+membranes+was+investigated+by+transport+experiments.+The+four+probe+solutes+were+toluene%2C+%C2%A6%C3%81%2C%C2%A6%C3%81%2C%C2%A6%C3%81-trifluorotoluene%2C+nitrobenzene+and+pentafluoronitrobenzene.+The+permeability+coefficients+of+the+probe+solutes+are+found+to+be+very+sensitive+to+the+FC-70+content+and+the+temperature.+The+permeability+coefficients+of+all+solutes+change+with+FC-70+in+a+similar+way.+They+decrease+initially+as+FC-70+content+increases+at+low+FC-70+concentration+with+reversal+of+this+trend+at+higher+FC-70+concentration%2C+and+decrease+again+and+finally+level+off.+Teflon+AF+membranes+with+less+than+10+wt%25+FC-70+could+be+associated+with+the+polymer%C2%A1%C2%AFs+anti-plasticization%2C+an+effect+indicated+by+a+reduction+in+the+free+volume%2C+a+decrease+in+the+glass+transition+temperature+and+a+reduction+in+the+partition+ratio+and+permeability+coefficient.+Teflon+AF+membranes+with+10+wt%25+FC-70+or+more+could+be+plasticized%2C+resulting+in+lower+glass+transition+temperature%2C+higher+free+volume+and+higher+permeability+coefficient.+Selectivity+of+the+membranes+was+investigated+for+the+pair+%C2%A6%C3%81%2C%C2%A6%C3%81%2C%C2%A6%C3%81-trifluorotoluene%2Ftoluene+and+for+the+pair+pentafluoronitrobenzene%2Fnitrobenzene.+It+reaches+a+maximum+at+10+wt%25+FC-70+for+both+pairs+at+20oC.+10+wt%25+FC-70+is+likely+a+turning+point+of+plasticization%2C+which+is+quite+interesting+since+it+is+also+related+to+the+highest+selectivity.Teflon+AF+membranes+could+also+be+plasticized+by+the+organic+liquid+with+which+it+is+in+contact.+Chloroform+seems+to+plasticize+the+membranes+(they+get+pliable)+and+change+the+properties+of+the+membranes+to+a+less+%C2%A1%C2%AEfluorous%C2%A1%C2%AF+environment.+The+concentration+of+FC-70+may+change+during+transport+experiments.+We+thus+need+to+find+a+means+to+plasticize+the+films+while+keeping+them+fluorous.&rft.date=2006-06-29&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%2F6386%2F1%2F2006JieZhangThesis.pdf&rft.identifier=++Zhang%2C+Jie++(2006)+Teflon+AF+membrane+transport+of+organic+solutes.++Master's+Thesis%2C+University+of+Pittsburgh.++++(Unpublished)++