The objective of this study was to assess the physicochemical effects of hydrating a hydrophobic end-capped poly(lactide-coglycolide)(PLGA)polymerintheliquidandvaporstate.PLGARG503polymerwasincubatedat37∘Cin0.5%polyvinylalcohol (PVA)solutionandat90%RH.Sampleswerewithdrawnatpredeterminedintervalsandchangestopolymerpropertieslikeglass transition temperature (Tg), moisture uptake, molecular weight change, and % acid number were determined using differential scanningcalorimetry,KarlFishertitrimetry,gelpermeationchromatography,andacidbasetitrimetry,respectively.Studyresults showed that Tg was depressed instantaneously upon hydration, indicating that bulk water acted as a plasticizer of hydrophobic end-cappedPLGA.Tg valuesdecreasedtolevelsbelowtheincubationtemperaturewhenhydratedin0.5%PVAsolutionbutnotin 90%RH.ThedropinTg exhibitedalinearrelationship(2 > 0.99)totheamountofwateruptakebythepolymer;highermoisture uptakewasnotedwithliquidwater.RemovalofmoisturefromthepolymermatrixresultedinrecoveryofTg,onlyuptoaperiod of14days.Presenceofwaterinliquidorvaporformcausedareductioninmolecularweightofthepolymerandacorresponding increasein%acidnumberoverthedurationofthestudy.
Effect of Hydration on Physicochemical Properties of End-Capped PLGA
DORATI, ROSSELLA;
2014-01-01
Abstract
The objective of this study was to assess the physicochemical effects of hydrating a hydrophobic end-capped poly(lactide-coglycolide)(PLGA)polymerintheliquidandvaporstate.PLGARG503polymerwasincubatedat37∘Cin0.5%polyvinylalcohol (PVA)solutionandat90%RH.Sampleswerewithdrawnatpredeterminedintervalsandchangestopolymerpropertieslikeglass transition temperature (Tg), moisture uptake, molecular weight change, and % acid number were determined using differential scanningcalorimetry,KarlFishertitrimetry,gelpermeationchromatography,andacidbasetitrimetry,respectively.Studyresults showed that Tg was depressed instantaneously upon hydration, indicating that bulk water acted as a plasticizer of hydrophobic end-cappedPLGA.Tg valuesdecreasedtolevelsbelowtheincubationtemperaturewhenhydratedin0.5%PVAsolutionbutnotin 90%RH.ThedropinTg exhibitedalinearrelationship(2 > 0.99)totheamountofwateruptakebythepolymer;highermoisture uptakewasnotedwithliquidwater.RemovalofmoisturefromthepolymermatrixresultedinrecoveryofTg,onlyuptoaperiod of14days.Presenceofwaterinliquidorvaporformcausedareductioninmolecularweightofthepolymerandacorresponding increasein%acidnumberoverthedurationofthestudy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
