The study of mechanism of organic additives action in the polysulfone membrane casting solution

Desalination,83(1991)343-360ElsevierSciencePublishersB.V.,AmsterdamTHESTIJDYOFMECHANISMOFORGANICADDITIVESACTIONINTHEPOLYSULFONEMEMBRANECASTINGSOLUTION*I-IOUTAI-PINGDONGSHENG-HUAZHENGLING-YINGDalianInstituteofChemicalPhysics,AcademiaSinica,P.O.Box110,Dalian(China)SUMMARYTheinteractionbetweenpolysulfone(PS)and71lowmolecularweightorganiccompoundswithdiffe-rentfunctionalgroupshavebeenstudiedbythegasliquidchromatography(GLC).Thefreeenergyofsolu-tionandheatofsolutionofthesecompoundstoPSpolymerhavebeenobtained,andthefreeenergyofsolutionhasbeencorrelatedtotheselectedorganicadditivesinPS-dimethylacetamide(DMAC)castingso-lutions.Accordingtothecloudpointandtherheo-logicalpropertiesofPS-DMRC-additivessolutions,aswellastheeffectofadditivesontheporesizeinthemembranesurface,themechanismoftheactionoforganiccompoundsinPSmembranecastingsolutionhasbeenproposed.Themodelsuggestedmaygiveasatisfactoryexplanationtotheexperimentalresults.INTRODUCTIONGernerallythemembranecastingsolutionconsistsofpolymer,solventandadditives.Whenthemembranematerialandrelevantsolventaredetermined,thenatureofadditivesisthemostactivefactoraffe-ctingthestructureandstateofcastingsolutions.Thestructureandperformanceofresultingmembranecanbecontrolledthroughselectingdif.$erentorga-nicadditivesaswellasthedifferentamountofadditives.Intheearlydayof609,thestudywasfocusedontheinorganicsaltadditives(l).Theroleofinorganicsaltadditivesincastingsolutionhasbeenconsideredasfollows:thesaltionshave*TheprojectissupportedbyNSFC343344changedtheinteractionbetweenthemacromoleculechainsandthesaltitselfhasgivenaplaceforporeformationduringgelation.Soonafterwardstheorganicadditiveshavebeenused.Inthestudytotheorganicadditivesaction(2-7)thedifferentexperimentalmethodshavebeenused.Theconclusionisthatthemembraneporousstructureoriginatedfromtwokindsofstructureofpolymermoleculesinthecastingsolution,i.e.thepolymernetworkandaggregatestructure.Theactionoforganicadditivesincastingsolutionhasbeenconsideredaffectingthepropertiesofpolymernetworkandaggr