Chap 6 Gel Chromatography6.1 Background6.2 Principles of Gel Chromatography6.3 Data Treatment6.4 Applications on Polymers6.5 Field-Flow Fraction (FFF) Technique GPC GPC18601930: porous materials have adsorption-separation function (especially for dye)19401970: appearance of Liquid Chromatography 1964: The first GPC produced by Waters company1970: HPLC （rapid test 、good separation effects、less sample、more sensitive）;New technology of HPLC applied in GPC area6.1 Background6.1 BackgroundnSignificance of Molecular Weight Distribution (MWD) nStatistic Average Molecular WeightnExpressions of MWDnMeasurement of MWDRelation between molecular weight and properties of polymer6.1.2 Statistic Average Molecular WeightnNumber-average Molecular WeightnWeight-average Molecular Weight6.1.2 Statistic Average Molecular WeightnZ-average Molecular WeightnViscosity-average Molecular Weight6.1.3 Expressions of MWDnParameterslBreadth parameter of molecular weight distribution: variance and standard deviation between different molecular weights and the average molecular weightlPolydispersity index of molecular weight: 6.1.3 Expressions of MWDnGraphic MethodslDiscrete distribution curveslContinual distribution curves 6.1.4 Measurement of MWDnTheorieslReactions: terminal analysislThermodynamics of dilute solutions: colligative properties (boiling point elevation, freezing point depression, osmotic pressure)lKinetics: ultracentrifugal sedimentation, viscosity, volume exclusionlOptical properties: scattering 6.1.4 Measurement of MWD6.2 Principles of Gel ChromatographynHigh Performance Liquid Chromatography (HPLC)nGel ChromatographynSeparation Mechanisms6.2.1 HPLCnDefinitionn High Performance Liquid ChromatographylAlso called high pressure liquid chromatographySmall particles of stationary phase: 10 mHigh pressure injection pumpsAutomatic detectors6.2.1 HPLCnClassificationlAdsorption chromatographyStationary phase: absorbentsAdsorption of mobile phaseGradient elutionApplications: additives in polymers6.2.1 HPLCnClassificationlDistribution chromatographyLiquid-liquid chromatographyNormal phase LLC / Reverse phase LLC: polarityBonded stationary phase6.2.1 HPLCnClassificationlIon-exchange chromatographyStationary phase: ion-exchange resinApplications: amino acids, proteins6.2.1 HPLCnClassificationlGel chromatographyStationary phase: porous gel-like packingsLarge molecules retention value / small molecules retention value Also called “gel exclusion chromatography (GEC)”nGel permeation chromatography (GPC): organic solventnGel filtration chromatography (GFC): water1.GPCMobile phase in GPCMobile phase pump auto-injector column(s) detector(s) data acquisitionTemperature controlMobile phase（solvents） organic solvents（THF、CHCl3、DMF ） waterGel in GPCMobile phase pump auto-injector column(s) detector(s) data acquisitionTemperature controlKinds of gel in column crosslinked copolymer of St and DVB porous glass、porous silica、porous Al2O3 flexible material（聚醋酸乙烯酯凝胶、聚丙烯酰胺凝胶、葡萄糖凝胶）Choice of gel (pore diameter)According to MColumn in GPCMobile phase pump auto-injector column(s) detector(s) data acquisitionTemperature control uniform pore diameter different pore diameter 分子量范围已知，选择单一孔径；分子量范围未知，选择混合床柱得到精确的分子量分布探索分子量范围6.2.1 Detectors in HPLCnInstrumentationlDetectorsConcentration: refraction, UVLight Scattering / ViscosityMobile phase pump auto-injector column(s) detector(s) data acquisitionTemperature controlGPC系统之温度控制Mobile phase pump auto-injector column(s) detector(s) data acquisitionTemperature control柱温控制 environment temperature less than 50 C highest control temperature less than 150 C different solvents, different temperature（THF:35 C , DMF:85 C ）6.2.3 Separation MechanismsnThe Fundamental Equation:C: the elution volumeVM: the void volume of the mobile phaseVS: the calculative internal volume within the porous particlesK: the distribution coefficientn0 K 1nVery large molecules: K=0, VR = VMnSmall molecules: K=1, VR = VM + VS6.2.3 Separation MechanismsnEquilibrium exclusion theory: suitable for most situations Limited diffusion theory: high flow velocityFlow separation theory: very high flow velocity6.3 Data TreatmentnGel ChromatogramsnCorrection Curve of Molecular WeightnCalculation of DMWnCorrection of Width of Peak6.3.1 Gel ChromatogramsnPlots:lHorizontal axis: the retention values of the effluent logarithm of MWlVertical axis: concentration of eluentlMonodispersive samples: Gaussian distribution curvelPolydispersive samples: sum of distribution curves of monodispersive samples6.3.2 Correction Curve of Molecular WeightnKeys:lTransition from VR to MWlCorrection curve of molecular weight: lgM-V6.3.2 Correction Curve of Molecular WeightnDirect Methods:lCorrection by monodispersive standards Exclusion limit / permeation limitlAsymptote method: correction curves for wide distribution samples 单分散性标准曲线Universal calibration method Hydrodynamics volumeRetention volumeFlexibility of macromolecule流体力学体积与保留体积的关系曲线具有普适性，称为普适标准曲线普适标准曲线=2.5NAVh/MM= 2.5NAVh1M1= 2M2 ： 特性黏数NA ：阿伏伽德罗常数Vh ：聚合物链等效球 的流体力学体积K、为每一特定高分子-溶剂体系的常数普适标准曲线Narrow-disperse Ps as guide sample6.4 Applications on PolymersnApplications in ProductionnCopolymersnBranching DegreenMeasurement of Materials of Low MoleculesnAging Process6.4.1 Applications in Production5.4.1 Inverse Gas ChromatographynCrystallinity and Crystalization KineticslCrystallinitylCrystalization Kinetics: Xc-t 6.4.2 CopolymersnHypenation with other methods 6.4.2 CopolymersnDouble Detectors 6.4.4 Measurement of Materials of Low Molecules6.4.5 Gas Chromatography6.5 Field-Flow Fraction (FFF) TechniquenBackgroundnPrinciplesnExperiments