高分子材料研究方法凝胶色谱法.ppt

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 GPCØ1860~1930: porous materials have adsorption-separation function (especially for dye)Ø1940~1970: appearance of Liquid ChromatographyØ 1964: The first GPC produced by Waters companyØ1970: HPLC （rapid test 、good separation effects、less sample、more sensitive）;New technology of HPLC applied in GPC area6.1 Background6.1 BackgroundnSignificance of Molecular Weight Distribution (MWD) nStatistic Average Molecular WeightnExpressions of MWDnMeasurement of MWDRelation between molecular weight and properties of polymer6.1.2 Statistic Average Molecular WeightnNumber-average Molecular WeightnWeight-average Molecular Weight6.1.2 Statistic Average Molecular WeightnZ-average Molecular WeightnViscosity-average Molecular Weight6.1.3 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 MWD6.2 Principles of Gel ChromatographynHigh Performance Liquid Chromatography (HPLC)nGel ChromatographynSeparation Mechanisms6.2.1 HPLCnDefinitionn High Performance Liquid ChromatographylAlso called high pressure liquid chromatography①Small particles of stationary phase: <10 μm②High pressure injection pumps③Automatic detectors6.2.1 HPLCnClassificationlAdsorption chromatography①Stationary phase: absorbents②Adsorption of mobile phase③Gradient elution④Applications: additives in polymers6.2.1 HPLCnClassificationlDistribution chromatography①Liquid-liquid chromatography②Normal phase LLC / Reverse phase LLC: polarity③Bonded stationary phase6.2.1 HPLCnClassificationlIon-exchange chromatography①Stationary phase: ion-exchange resin②Applications: amino acids, proteins6.2.1 HPLCnClassificationlGel chromatography①Stationary phase: porous gel-like packings②Large molecules → ↓ retention value / small molecules → ↑ retention value ③Also called “gel exclusion chromatography (GEC)”nGel permeation chromatography (GPC): organic solventnGel filtration chromatography (GFC): water1.GPCMobile phase in GPCMobile phase pump auto-injector column(s) detector(s) data acquisitionTemperature controlMobile phase（solvents）• organic solvents（THF、CHCl3、DMF ）• waterGel 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 MColumn 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 HPLCnInstrumentationlDetectors①Concentration: refraction, UV②Light Scattering / ViscosityMobile phase pump auto-injector column(s) detector(s) data acquisitionTemperature controlGPC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:①C: the elution volume②VM: the void volume of the mobile phase③VS: the calculative internal volume within the porous particles④K: the distribution coefficientn0 ≤ K ≤1nVery large molecules: K=0, VR = VMnSmall molecules: K=1, VR = VM + VS6.2.3 Separation MechanismsnEquilibrium exclusion theory: suitable for most situations Limited diffusion theory: high flow velocityFlow separation theory: very high flow velocity6.3 Data TreatmentnGel ChromatogramsnCorrection Curve of Molecular WeightnCalculation of DMWnCorrection of Width of Peak6.3.1 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 samples6.3.2 Correction Curve of Molecular WeightnKeys:lTransition from VR to MWlCorrection curve of molecular weight: lgM-V6.3.2 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[]=2.5NAVh/M[]M= 2.5NAVh[]1M1= []2M2[] ： 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 sample6.4 Applications on PolymersnApplications in ProductionnCopolymersnBranching DegreenMeasurement of Materials of Low MoleculesnAging Process6.4.1 Applications in Production5.4.1 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 Molecules6.4.5 Gas Chromatography6.5 Field-Flow Fraction (FFF) TechniquenBackgroundnPrinciplesnExperiments。