《基础化学》英文教学课件：chapter-5

Chapter5.Colloids§5-1.colloids§5-2.Sol§5-3.Macromolecularsolution§5-4.SurfactantsandassociatedcolloidsChapter5.Colloids§5-1.coll1胶体分散系明确分散系；分散相；分散介质；均相体系；非均相体系；相的概念；明确比表面；表面能的概念；明确分散相的分类方法；2溶胶明确溶胶；电泳；电渗；临界聚沉浓度的概念；理解溶胶的性质：光学性质；动力学性质；电学性质明确溶胶的结构：胶核；胶粒；吸附层；扩散层；双电层概念理解胶粒的电属性；理解溶胶的稳定性及聚沉；LearningObjectives1胶体分散系LearningObjectives3高分子溶液明确高分子溶液；等电点的概念；理解高分子溶液的属性；理解盐析，电泳分离和纯化蛋白的机制；4表面活性剂和缔合胶体明确表面能；表面张力；增溶的概念；明确胶束；临界胶束浓度；缔合胶体的概念；理解表面活性剂的分类；3高分子溶液§1.ColloidsAsolutionisahomogeneous(均相的)

mixtureoftwoormoresubstances,consistingofionsormolecules.Acolloid(胶体)

isadispersionofparticles(1~100nm)ofonesubstancethroughoutanothersubstanceorsolution.Conceptintroduction:NaClaqueoussolution:Na+,Cl-,H2OFogisanexampleofacolloid:itconsistsofverysmallwaterdropletsinair.Proteins,nucleicacids,blood,bodyfluid,cell.§1.ColloidsAsolutionisahoT.ThomasGraham(1805～1869)PeterP.vonWeymarn(1879–1935)扩散速度小，不能透过半透膜，溶剂蒸发后不结晶，而是形成无定形胶状物的物质。T.ThomasGraham(1805～1869)任何能结晶的物质在一定介质中用适当的方法都能成为胶体胶体是物质的一种分散状态的概念§1.ColloidsT.ThomasGrahamPeterP.vonWe§1.ColloidsI.DispersedsystemDispersedphase(分散相):

tobedispersed,discontinuousDispersedmedium(分散介质):

todisperse,continuousAdispersedsystem(分散系)

isformedbydispersingoneormoresubstancesthroughoutanothersubstance.§1.ColloidsI.Dispersedsyste§1.ColloidsClassificationofdispersedsystems:AAheterogeneoussystem(非均相体系)isamixturethatconsistsofphysicallydistinctparts,eachwithdifferentproperties.Ahomogeneoussystem(均相体系,alsoknownasasolution)isamixturethatisuniforminitspropertiesthroughoutgivensamples.K2CrO4+Fefillings§1.ColloidsClassificationof§1.ColloidsAphase(相)isoneofseveraldifferenthomogeneousmaterialspresentintheportionofmatterunderstudy.Theseheterogeneoussystemsallconsistoftwodifferentphases.K2CrO4+FefillingsicewatericeNaClsolution§1.ColloidsAphase(相)isone§1.ColloidsClassificationofdispersedsystems:BClassificationaccordingtothesizeofdispersedphase.§1.ColloidsClassificationofSol固-液Sol液-气Sol固-气ColouredstainedglassSol固-固Sol固-液Sol液-气Sol固-气Colour乳状液MilkyWay?凝胶乳状液MilkyWay?凝胶TheMilkyWayisthegalaxythatcontainsourSolarSystem.

AnimageoftheMilkyWay'sGalacticCenterinthenightskyaboveParanalObservatoryTheMilkyWayisthegalaxyth可怜织女星，化为马郎妇。

乌鹊疑不来，迢迢牛奶路。-出自鲁迅的《教授杂咏四首》TheMilkyWayisthegalaxythatcontainsourSolarSystem.

鲁迅(1881年9月25日-1936年10月20日）《呐喊》《狂人日记》《阿Q正传》可怜织女星，化为马郎妇。

乌鹊疑不来，迢迢牛奶路。-出自鲁迅§1.ColloidsII.ColloiddispersedsystemAcolloidisadispersionofparticles(1~100nm)ofonesubstance(thedispersedphase)throughoutanothersubstanceorsolution(thedispersedmediumorthecontinuousphase

(连续相)).Sol(溶胶)Macromolecularsolution(高分子溶液)Associatedcolloid(缔合胶体)§1.ColloidsII.Colloiddisper§1.Colloids1.SolAsol(溶胶)

isacolloidconsistingofsolidparticles(collectionofatoms,molecules,orions)dispersedinaliquid.heterogeneousandunstable§1.Colloids1.SolAsol(溶胶)i§1.ColloidsDegreeofdispersion(分散度):Acubewithasizeof1cm:Specificsurfacearea

(比表面,S0):surfaceareaoccupiedbythesubstanceofaunitvolume.1cm§1.ColloidsDegreeofdispersi§1.ColloidsDispersethecubetocubeswithasizeof1m,thenumberofsmallercubesis:Then,Dispersethecubetocubeswithasizeof1nm,thenumberofsmallercubesis:Then,1cm1m1nm§1.ColloidsDispersethecube§1.ColloidsAmoleculeatthesurfaceexperiencesanetforcetowardtheinterioroftheliquid,whereasamoleculeintheinteriorexperiencesnonetforce.Thereisatendencyforthesurfaceareaofaliquidtobereducedasmuchaspossible.Thisexplainswhyfallingraindropsarenearlyspherical(thespherehasthesmallestsurfaceareaforagivenvolumeofanygeometricalshape).§1.ColloidsAmoleculeatthe§1.ColloidsSurfaceenergy(表面能):Theenergyrequiredtoincreasethesurfaceareabyaunitamount.(J·m-2).OR.Themoleculesatthesurfacehavehigherenergythanthoseintheinterior.Solishighlydispersedandhasahighersurfaceenergy.Ithasatendencytoaggregatetodecreasethesurfaceenergy.Therefore,solisanunstablesystem.energy§1.ColloidsSurfaceenergy(表面§1.ColloidsThedispersedphaseissingle(large)molecules,macromolecularsolutionsarestablesystems.2.Macromolecularsolution(高分子溶液)§1.ColloidsThedispersedphas§1.ColloidsThedispersedphaseismolecularcluster.Associatedcolloidsarestablesystems.3.Associatedcolloid(缔合胶体)Sodiumstearate(硬脂酸钠)§1.ColloidsThedispersedphas§2.SolMulti-phase;Highly-dispersed;Unstable.§2.SolMulti-phase;Highly-disp§2.SolI.Propertiesofsol1.Opticalproperties(光学性质):TyndalleffectThescattering(散射)

oflightbycolloidal-sizeparticlesisknownastheTyndalleffect.Alightbeamisvisibleperpendiculartoitspathonlyiflightisscatteredtowardtheviewer.Colloidsolution§2.SolI.Propertiesofsol1.§2.SolScatteringof(strong)laserbeamsbyairmolecules§2.SolScatteringof(strong)§2.Sol§2.Sol§2.SolRayleighformula:I0:Incidentlightintensityλ:IncidentlightwavelengthV:particlevolume

c:concentrationofparticles

n:refractiveindex(折光指数)Colloidsolution§2.SolRayleighformula:I0:In§2.SolAlthoughallgasesandliquidsscatterlight,thescatteringfromapuresubstanceortruesolutionisquitesmallandusuallynotdetectable.However,becauseoftheconsiderabledepthoftheatmosphere,thescatteringoflightbyairmoleculescanbeseen.Thebluecoloroftheskyisduetothefactthatbluelightisscatteredmoreeasilythanredlight.Rayleighformula:I0:Incidentlightintensityλ:IncidentlightwavelengthV:particlevolume

c:concentrationofparticles

n:refractiveindex§2.SolAlthoughallgasesand两眼一眨不眨勇敢的盯着太阳直到太阳和我都变瞎天黑了地黑了太阳也黑了好久好久才醒过来感觉到天地由黑转白黎明从我这里向四面八方展开牛汉-----童癖六首（1923年10月－2013年9月29日）

两眼一眨不眨牛汉-----童癖六首（1923年10月－201Rayleighscatteringismoreevidentaftersunset.Thispicturewastakenaboutonehouraftersunsetat500maltitude,lookingatthehorizonwherethesunhadset.早霞不出门，晚霞行千里Rayleighscatteringismoreev§2.Sol2.Dynamicproperties(动力学性质)

Brownianmovement(布朗运动): Thephenomenonthatcolloidalparticlesmoveirregularlyandcontinuouslyinthemedium.§2.Sol2.Dynamicproperties(§2.SolItisresultedfromtheunbalancedcollisionfrommediummolecules.Decreasingsolparticlesizeandviscosity(粘度)ofmedium,orincreasingthetemperature,favorsBrownianmovement.Sol:dynamicallystablesystem.§2.SolItisresultedfromthe§2.Sol

Diffusionandsedimentationequilibrium:Diffusion(扩散):

Thephenomenonthatcolloidalparticlesshiftfromaregionwithhigherconcentrationtothatwithlowerconcentration.

Reason:Brownianmovement;

Drivingforces:concentrationdifference.§2.SolDiffusionandsedimen§2.SolSedimentation(沉降):

Thephenomenonthatcolloidalparticlestendtosinkduetogravitation.Sedimentationequilibrium:whendiffusionandsedimentationareatequilibrium,aconcentrationgradient(梯度)occurs.Ittakesaverylongtimetoreachthisequilibrium,toacceleratethisprocess……§2.SolSedimentation(沉降):TheUltracentrifugation(超速离心法)§2.SolUltracentrifugation(超速离心法)§2.在密度均一的介质中由低速到高速逐级离心，用于分离不同大小的细胞和细胞。differential

centrifugation

差速离心

在密度均一的介质中由低速到高速逐级离心，用于分离不同大小的细density

gradient

centrifugation

密度梯度离心用一定的介质在离心管内形成一连续或不连续的密度梯度，将细胞混悬液或匀浆置于介质的顶部，通过重力或离心力场的作用使细胞分层、分离。

A等速度沉降，分离密度相近而大小不等的细胞或细胞器。B等密度沉降

,适用于分离密度不等的颗粒。density

gradient

centrifugatio§2.Sol+-3.Electricproperties

Electrophoresis:§2.Sol+-3.Electricpropertie§2.SolElectrophoresis(电泳):

directionalmovementofchargedcolloidalparticlesinanelectricfield.+-NaClsolutionFe(OH)3solPositively-chargedFe(OH)3colloidalparticlesApplications:

separationandidentificationofaminoacids,polypeptides,proteins,andnucleicacids.§2.SolElectrophoresis(电泳):d§2.SolInstrumentforelectrophoresis.Separationandidentificationproteinsbyelectrophoresis.§2.SolInstrumentforelectrop§2.Sol§2.Sol§2.SolElectroosmosis(电渗):

directionalmovementofdispersedmediuminanelectricfield.Reason:

chargingstateofcolloidalparticlesandmedium.-colloidalparticlesfixedinamembrane+capillary(毛细管)§2.SolElectroosmosis(电渗):di§2.SolII.StructureofsolAgNO3+KIAgI+KNO3KIinexcess;AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+Colloidalparticle(胶粒)Colloidalnucleus(胶核)Sol1.Structureofsol§2.SolII.StructureofsolAgN§2.Sol{[AgI]m·nI-·(n-x)K+}x-·xK+ColloidalnucleusAdsorptionlayerDiffusionlayerColloidalparticleSolAgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+Colloidalparticle(胶粒胶粒)Colloidalnucleus(胶核胶核)SolAgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+Colloidalparticle(胶粒胶粒)Colloidalnucleus(胶核胶核)Sol§2.Sol{[AgI]m·nI-·(n-x)K+}x-·§2.SolAdsorptionlayer(吸附层):

thethinlayercomposedofadsorbedionsonthecolloidalnucleussurfaceandpartoftheconfinedcounterions(反离子).Diffusionlayer(扩散层):

thelayercomposedoftherestofcounterionsdiffusingaroundtheadsorptionlayer.Electricdoublelayer(双电层):

thetwo-layerstructureofoppositely-chargedadsorptionlayeranddiffusionlayer.Absorption(吸收)§2.SolAdsorptionlayer(吸附层):§2.Sol{[AgI]m·nAg+·(n-x)NO3-}x+·xNO3-ColloidalnucleusAdsorptionlayerDiffusionlayerColloidalparticleSolAgNO3+KIAgI+KNO3AgNO3

inexcess;AgINO3-Ag+ColloidalparticleColloidalnucleusSolAg+Ag+Ag+Ag+Ag+Ag+Ag+NO3-NO3-NO3-NO3-NO3-NO3-NO3-§2.Sol{[AgI]m·nAg+·(n-x)NO3-}§2.Sol{[Fe(OH)3]m·nFeO+·(n-x)Cl-}x+·xCl-ColloidalnucleusAdsorptionlayerDiffusionlayerColloidalparticleSolFeCl3+3H2OFe(OH)3+3HClFe(OH)3+HClFeOCl+2H2OFeOClFeO++Cl-Fe(OH)3Cl-FeO+ColloidalparticleColloidalnucleusSolFeO+FeO+FeO+FeO+FeO+FeO+FeO+Cl-Cl-Cl-Cl-Cl-Cl-Cl-§2.Sol{[Fe(OH)3]m·nFeO+·(n-x)§2.Sol2.Electrically-chargedcolloidalparticles1).Selectiveadsorptiontothecolloidalnucleussurface:

Fe(OH)3colloidalparticlesappeartobepositively-chargedduetoselectiveadsorptionofFeO+.Fe(OH)3Cl-FeO+ColloidalparticleColloidalnucleusSolFeO+FeO+FeO+FeO+FeO+FeO+FeO+Cl-Cl-Cl-Cl-Cl-Cl-Cl-§2.Sol2.Electrically-charged§2.SolAgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgNO3+KIAgI+KNO3AgINO3-Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+NO3-NO3-NO3-NO3-NO3-NO3-NO3-AgNO3

inexcessKIinexcess§2.SolAgIK+I-I-I-I-I-I-I-I-I-§2.SolSilicasolcolloidalparticlesappeartobenegatively-charged. H2SiO3HSiO3-+H+ HSiO3-SiO32-+H+2).Dissociationofsurfacemoleculesaroundcolloidalnucleus:Silicasol:Nucleus:xSiO2·yH2OSurface:H2SiO3§2.SolSilicasolcolloidalpa§2.SolAgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+3).EffectofelectrolyteelectrolyteelectrolyteelectrolyteAgI+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+AgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+K+AgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+K+§2.SolAgIK+I-I-I-I-I-I-I-I-I-§2.SolIII.StabilityofsolElectrically-chargedcolloidalparticles:Electrostaticrepulsionamongcolloidalparticles.Protectionofhydratedmembrane(水合膜)aroundcolloidalparticle:Elasticmembrane.Brownianmovement.Acolloidofgoldparticles(negatively-charged)inwaterpreparedbyMichaelFaradayin1857isstillpreservedintheBritishMuseuminLondon.§2.SolIII.StabilityofsolElSolutionsofgoldnanoparticlesofvarioussizes.Thesizedifferencecausesthedifferenceincolors.§2.SolSolutionsofgoldnanoparticle免疫金标记技术(Immunogoldlabellingtechique)

在金标蛋白结合处，在显微镜下可见黑褐色颗粒，当这些标记物在相应的配体处大量聚集时，肉眼可见红色或粉红色斑点，因而用于定性或半定量的快速免疫检测方法中，这一反应也可以通过银颗粒的沉积被放大，称之为免疫金银染色。纳米金即指金的微小颗粒，其直径在1～100nm，具有高电子密度、介电特性和催化作用，能与多种生物大分子结合，且不影响其生物活性。§2.Sol免疫金标记技术(Immunogoldlabellingtaccumulationsofgold

particlesovertheneuralgranules§2.Solaccumulationsofgold

particl§2.SolIV.CoagulationofsolCoagulation(聚沉)

istheprocessbywhichthedispersedphase(colloidalparticlesofsol)ismadetoaggregateandtherebyseparatefromthedispersedmedium(continuousphase).Anexampleisthecoagulationofacolloidalsuspensionofsoilinriverwaterwhenthewatermeetstheconcentratedionicsolutionofanocean.Theriverdelta(三角洲)wasformedinthisway.§2.SolIV.CoagulationofsolCNileRiverdelta,asseenfromEarthorbit.TheNileisanexampleofawave-dominateddeltathathastheclassicGreekdelta(δ,Δ)shapeafterwhichriverdeltaswerenamed.§2.SolNileRiverdelta,asseenfromDeltasonMarsFindingdeltasisamajorsignthatMarsoncehadalotofwater.

§2.SolDeltasonMarsFindingdeltas§2.SolElectrolytecanpushcounterionstotheadsorptionlayerandneutralize(中和)

thechargingstateofcolloidalparticles.Twocolloidalparticlescanapproachcloseenoughtoaggregate.Criticalcoagulationconcentration(CCC,临界聚沉浓度):

theminimumconcentrationofelectrolyteneededtocoagulateacertainamountofsolwithinaspecifiedtime.1.EffectofelectrolyteelectrolyteAgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+K+AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+§2.SolElectrolytecanpushco§2.SolCriticalcoagulationconcentration(mmol·L-1)§2.SolCriticalcoagulationco§2.SolA.Thegreaterthemagnitudeofthechargeofthecounterion,thelowertheCCCis.Shulze-Hardyrule:B.Samemagnitudeofthechargeofthecounterion,coagulationcapacity: Fornegatively-chargedsol: H+>Cs+>Rb+>NH4+>K+>Na+>Li+ Forpositively-chargedsol: F->Cl->Br->I->CNS-§2.SolA.Thegreaterthemagn§2.Sol2.CoagulationofmixedsolswithoppositeelectricchargesFe(OH)3Cl-FeO+FeO+FeO+FeO+FeO+FeO+FeO+FeO+Cl-Cl-Cl-Cl-Cl-Cl-Cl-+§2.Sol2.Coagulationofmixed§3.MacromolecularSolutionMacromolecule(polymer):achemicalspeciesofveryhighmolecularweight(>10,000)madeupfrommanyunitsoflowmolecularweightlinkedtogether.Macromolecularsolutionisakindofmolecularsolution.Itisahomogeneousandstablesystem.However,thesizeofmacromoleculesfallsintotherangeofcolloidaldispersedsystem.Polymersarenaturalorsynthetic(nextslide).I.Macromolecules§3.MacromolecularSolutionMacMacromolecularsolution

solHeterogeneoussystemHomogeneoussystemStablesystemsUnstablesystemsunchargedcolloidalparticlesChargedcolloidalparticlesViscosity,osmoticpressure

Lowviscosityandosmoticpressure

solvation,SaltingoutCoagulation§3.MacromolecularSolutionMacromolecularsolutionsolHetFlexible-chain:goodsolvent§3.MacromolecularSolutionFlexible-chain:goodsolvent§3§3.MacromolecularSolutionBranchedpolymer(枝化高分子)Hyperbranchedpolymer(高枝化高分子)Dendrimer(树形高分子)Linearpolymer(线形高分子)Uniformstructuralunit:Polyethylene(聚乙烯):(C2H4)nNaturalrubber:(C5H8)nPolysaccharide(多糖):(C6H10O5)nNon-uniformstructuralunit:Protein(蛋白质):aminoacidsNucleicacid(核酸):nucleotides(核苷)§3.MacromolecularSolutionBraApolymer(聚合物)isachemicalspeciesofveryhighmolecularmassmadeupfrommanystructuralunitormonomeroflowmolecularmasscovalentlylinkedtogether.Acompoundusedtomakeapolymer(andfromwhichthepolymer’sunitarises)iscalledamonomer(单体).§3.MacromolecularSolutionApolymer(聚合物)isachemicals“团结就是力量”§3.MacromolecularSolution“锁链化学”“团结就是力量”§3.MacromolecularSolCelluloid,discoveredaround1868,wasthefirstcommercialplastic.Initiallyitwasusedasacheapsubstituteforivoryinmakingbilliardballs.Cellulose(纤维)Cellulosenitrate(guncotton)ismadebysoakingacellulosematerialsuchascottoninamixtureofnitricandsulfuricacids.itcatchesfireandburnsexplosively.

Tabletennisballscelluloidfilm§3.MacromolecularSolutionCelluloid,discoveredaround1Bakelite,ahardplasticproducedfromformaldehyde,HCHO,andphenol,C6H5OH.LeoBaekeland利奥贝克兰(1863–1944)

Bakelitebuttons

Bakelite酚醛树脂(1907)§3.MacromolecularSolutionBakelite,ahardplasticproduNaturalrubberisahomopolymer(同聚物),apolymerwhosemonomerunitsareallalike.Acopolymer(共聚物)

isapolymerconsistingoftwoormoredifferentmonomerunits.Styrene–butadienerubber(SBR)isanimportantsyntheticrubber;§3.MacromolecularSolutionNaturalrubberisahomopolymePolyesters(聚酯)Asubstancewithtwoalcoholgroupsreactswithasubstancewithtwocarboxylicacidgroupstoformapolyester,apolymerwhoserepeatingunitsarejoinedbyestergroups.Dacron(涤纶)Theproduct,althoughinteresting,tendedtodecomposeinhotwaterandhadalowmeltingpoint,soasafabricitwouldhardlywithstandwashingorironing.§3.MacromolecularSolutionPolyesters(聚酯)Dacron(涤纶)ThepPolyamides

(聚酰胺)Whenacompoundcontainingtwoaminegroupsreactswithacompoundcontainingtwocarboxylicacidgroups,acondensationpolymercalledapolyamide

isformed.Nylon-6,6(尼龙，1935)Acondensationpolymer(缩合聚合物)isapolymerformedbylinkingtogethermanymoleculesbycondensationreactions.Acondensationreactionisoneinwhichtwomoleculesarejoinedbytheeliminationofasmallmoleculesuchaswater.§3.MacromolecularSolutionPolyamides(聚酰胺)Nylon-6,6(尼龙，WallaceCarothers华莱士·卡罗瑟斯(1896年－1937年)

§3.MacromolecularSolutionWallaceCarothers§3.MacromolePlexiglass(acrylic)有机玻璃(丙烯酸树脂)Teflon特氟龙(聚四氟乙烯)§3.MacromolecularSolution“不粘锅”涂层Plexiglass(acrylic)Teflon§3.§3.MacromolecularSolution§3.MacromolecularSolutionPETEPolyethyleneterephthalate聚对苯二甲酸乙二醇酯PP

Polypropylene聚丙烯§3.MacromolecularSolutionPETEPP§3.MacromolecularSoluHDPE

High-densitypolyethylene高密度聚乙烯LDPELow-densitypolyethylene低密度聚乙烯塑料§3.MacromolecularSolutionHDPELDPE§3.MacromolecularSPS

Polystyrene聚苯乙烯PVC

Polyvinylchloride聚氯乙烯§3.MacromolecularSolutionPSPVC§3.MacromolecularSoluPCPolycarbonates聚碳酸酯BisphenolA双酚Ａ§3.MacromolecularSolutionPCBisphenolA§3.Macromolec§3.MacromolecularSolutionII.Proteinsolution1.ProteinProtein(蛋白质)

arebiologicalpolymersofaminoacidslinkedbypeptidebonds.+peptidebond(肽键)Aminoacid(氨基酸)R:§3.MacromolecularSolutionII.§3.MacromolecularSolution2.IsoelectricpointLowerpHHigherpHSidechainsbecomeprotonatedandcarrypositivecharges.Sidechainsbecomedeprotonatedandcarrynegativecharges.Protonation(质子化)

meansthegainofaproton;Deprotonation(去质子化)

meansthelossofaproton.§3.MacromolecularSolution2.§3.MacromolecularSolutionThepHatwhichaproteincarriesnonetcharge(sameamountofnegativechargesandpositivecharges)iscalledtheisoelectricpoint(等电点,pI)ofthisprotein.pH<pI: positively-charged;pH=pI: nonetcharge;pH>pI: negatively-charged.Theisoelectricpointofbovineserumalbumin(牛血清白蛋白,BSA)is4.6.Isoelectricpointandelectrophoresis,solubility….§3.MacromolecularSolutionTheMorespecifically,thepIofanyaminoacidistheaverageofthetwoacid-dissociationconstantsthatinvolvetheneutralzwitterion.Forthe13aminoacidswithaneutralsidechain,pIistheaverageofpKa1andpKa2.Forthefouraminoacidswitheitherastronglyorweaklyacidicsidechain,pIistheaverageofthetwolowestpKavalues.Forthethreeaminoacidswithabasicsidechain,pIistheaverageofthetwohighestpKavalues.§3.MacromolecularSolutionMorespecifically,thepIof§3.MacromolecularSolution3.SaltingoutTheprimarystructure(一级结构)

ofaproteinreferstothesequenceoftheamino-acidunitsintheprotein.Thesecondarystructure(二级结构)

referstotherelativelysimplecoiledorparallelarrangementofaproteinmolecule.Thetertiarystructure(三级结构)

referstothestructureassociatedwiththewaytheproteincoilisfolded.Three-dimensionalstructureofmyoglobin(肌球素)§3.MacromolecularSolution3.§3.MacromolecularSolutionDuetotheion-dipoleforces(离子-偶极作用力),thecharges(ions)alongproteinmoleculesattractwatermoleculesandarethushydrated.Hydration(水合作用)

ofionsfavorsthedissolvingofproteinmoleculesinwater.Hydrationofions.Notethatacation(a)issurroundedbywatermoleculeswiththeOatomsclosertotheion,whereasananion(b)haswatermoleculesattachedthroughtheirhydrogenatoms.§3.MacromolecularSolutionDue§3.MacromolecularSolutionWheninorganicsalt(forexample,(NH4)2SO4))areaddedintoproteinsolution,thehydrationofproteinmoleculesishighlyweakenedduetothestronghydrationofinorganicions.Thesolubilityofproteinisloweredandproteinmoleculesprecipitateoutofthesolution.Thisprocessisreferredtoassaltingout(盐析).Thestructureofproteinmoleculesremainswhensaltedout.Saltingoutisaroutineproceduretoseparateandpurifyproteins.Organicexperimentslastterm?globin(球蛋白)andalbumin(清蛋白)§3.MacromolecularSolutionWhe§4.SurfactantsandAssociatedcolloidI.surfacetensionSurfaceenergy(表面能):Theenergyrequiredtoincreasethesurfaceareabyaunitamount.(J·m-2).Surfacetension(表面张力,):Theforceexertedonaunitlengthofthesurfacetocontractthesurfacearea.Surfaceenergyandsurfacetensionhavethesamevalue.§4.SurfactantsandAssociated§4.SurfactantsandAssociatedcolloidsurfacetension§4.SurfactantsandAssociatedThesurfacetensionofliquidwateris73mN·m-1.Organicsolventshavemuchlowersurfacetensions.§4.SurfactantsandAssociatedcolloidThesurfacetensionofliquidII.Surfactant(表面活性剂)(Surface-active-agent)soluteconcentration(surfactant)A:InorganicadditivessuchasNaCl,KNO3.B:Organicadditivessuchasalcohol(醇),aldehyde(醛),carboxylicacid(羧酸),andester(酯).C:Surfactantssuchassoapsanddetergents.Thesurfacetensionofaliquidcanbeaffectedbydissolvedsubstances.§4.SurfactantsandAssociatedcolloidII.Surfactant(表面活性剂)solute1.StructureofsurfactantmoleculesAmphiphile(两亲分子)Hydrophilic(亲水的)Hydrophobic(疏水的)orlipophilic(亲油的)headtail§4.SurfactantsandAssociatedcolloidsodiumdodecylsulfate(十二烷基硫酸钠)1.Structureofsurfactantmol2.ClassificationofsurfactantsAnionic:(阴离子表面活性剂)Cationic:(阳离子表面活性剂)Zwitterionic:(两性离子表面活性剂)Nonionic:(非离子表面活性剂)R=C14,C16,orC18Lecithin(卵磷脂)§4.SurfactantsandAssociatedcolloid2.Classificationofsurfactan§4.SurfactantsandAssociatedcolloidIncreasingconcentrationsofsurfactantAdsorption(吸附)

ofsurfactantmoleculestothesurfaceFormationoffulllayerofsurfactantmoleculesonthesurfaceFormationofmicelles(胶束)

inthesolution§4.SurfactantsandAssociated§4.SurfactantsandAssociatedcolloidsoluteconcentration

(surfactant)Organicsubstanceshavemuchlowersurfacetensionthanwater,thesurfacetensionofthesolutionisgreatlyreduced.§4.SurfactantsandAssociatedIII.AssociatedcolloidAmicelle(胶束)

isacolloidal-sizedparticleformedinwaterbytheassociationofsurfactantmolecules.Theminimumconcentrationofsurfactantsatwhichthemicellestartstoformisreferredascriticalmicelleconcentration(CMC,临界胶束浓度).§4.SurfactantsandAssociatedcolloidThehydrophobicendspointinwardoneanother,andthehydrophilicendsareontheoutsideofthemicellefacingthewater.III.AssociatedcolloidAmicel§4.SurfactantsandAssociatedcolloidAcolloidinwhichthedispersedphaseconsistsofmicellesiscalledanassociatedcolloid(缔合胶体).Themicellescouldbespherical,rod-shaped,orlayereddependingonthestructureandconcentrationofsurfactants,temperature,andadditives.§4.SurfactantsandAssociatedwatermicelleoilSolubilization(增溶):Thesolubilityofoilisenhancedinassociatedcolloids.§4.SurfactantsandAssociatedcolloidwatermicelleoilSolubilization§4.SurfactantsandAssociatedcolloidThecleaningactionofsoapsoccursbecauseoilandgreasecanbesolubilizedintothecentersofsoapmicellesandwashedaway.§4.SurfactantsandAssociatedIV.StructuresofcellmembranePhospholipids(磷脂)arethemainconstituentsofthemembraneoflivingcells.Lecithins(卵磷脂)aretypicalphospholipids.R=C14,C16,orC18§4.SurfactantsandAssociatedcolloidIV.Structuresofcellmembran§4.SurfactantsandAssociatedcolloid§4.SurfactantsandAssociatedPhospholipidmoleculesinwatertendtoassociatesothattheirhydrophilicheadsdipintothewater,withtheirhydrophobicta