简介：Yttriumoxidenanopowderwaspreparedbyanoveltechniqueusinganalginatebiopolymerasaprecursor.Thetechniqueisbasedonthermaldecompositionofanyttriumalginategel,whichisproducedintheformofbeadsbyionicgelationbetweentheyttriumsolutionandsodiumalginate.Theeffectofpost-annealingtemperatureontheparticlesizeofthenanocrystalswasinvestigatedatvarioustemperatures.TheproductswerecharacterizedusingX-raydiffraction,scanningelectronmicroscopy,andatomicforcemicroscopy.ThesizeofthenanocrystallineY2O3particlesvariedfrom22.7to38.7nm,dependingontheannealingtemperatureandtime.Thegrainsizedistribution（GSD）wasalsodetermined.TheGSDbecamemorenon-symmetricalastheannealingtemperatureincreased,andthewidthofthedistributionsforthepowdersproducedusingthealginatemethodwaslessaffectedbyheattreatment.Thisalginatemethodwascomparedwiththeconventionalglycinecombustionmethod,onthebasisofparticlesize.Theparticlesobtainedusingtheproposedtechniqueweresmallerthanthoseobtainedusingthecombustionmethod.Alginate-assistedthermaldecompositionisthereforeaneasyandcost-effectivemethodforpreparingnanosizedY2O3crystals.

简介：Asupercriticalcarbondioxide(ScCO2)assistedphaseinversionwasdevelopedtoproducemicroporouspoly(vinylidenefluoride)(PVDF)membraneswhosemorphologycharacteristicsarisefrombothliquid-liquiddemixingandsolid-liquiddemixing(crystallization).ThisresultwasconfirmedbyFouriertransforminfraredspectroscopy(FTIR),fromwhichbothαandβcrystalswerefound.Asrevealedbycontactangleexperiment,thePVDFmembranespreparedviaScCO2assistedphaseinversionweremorehydrophobiccomparedwiththecontrolmembraneproducedviaconventionalimmersionprecipitationtechnique.Inparticular,thesamplewith15wt%PVDFpreparedat45°Cand13MPaexhibitedacontactangleof142°,whichwasmainlycausedbythemultilevelmicro-andnano-structure.Theeffectsofpolyethyleneglycol(PEG),polyvinylpyrrolidone(PVP)andlithiumchloride(LiCl)onthestructuresandcrystalformwereinvestigated.PVPpromotedtheformationofβphasecrystalform,whilePEGbooststheevolutionofαphase.LiClrestrainedthecrystallizationdegreeofPVDFmembraneunderScCO2.

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