表界面化学表面活性剂

表界面化学表面活性剂3、1Molecularstructureofsurfactant结构上双亲物质得定义Anamphiphileisasubstancethatbinesintheonemoleculeasegmentthattendstowaterinsoluble(不溶于水)andoilsoluble(溶于油),i、e、hydrophobicoroleophilic,andasegmentthattendstobewatersoluble,i、e,hydrophilic、Phospholipidshaveamphipathiccharacter、磷脂得分子结构BEAConfidential、|33、1MolecularstructureofsurfactantAsurfactantisapoundthatlowersthesurfacetension(降低表面张力)ofaliquid,increasingthecontactbetweentheliquidandanothersubstance、功能上表面活性剂得定义3、1MolecularstructureofsurfactantSurfactantsarewater-solubleamphiphilesandarestronglyadsorbedatsurfaces、Thedrivingforceforthisstrongadsorptionesfromtheamphiphilcnatureofthesurfactantmolecule、表面活性剂可在表面吸附强烈,驱动力来自于其双亲性。3、1MolecularstructureofsurfactantThehydrophobicportionofthemoleculecanbelargelylocatedinthevapourphaseoutofwaterwhilethehydrophilicportioncanbeimmersedinthewater、疏水端在气相,亲水端在水相3、1MolecularstructureofsurfactantSuchadsorbedfilmsareknownasGibbsmonolayers(Monolayerbecausethereisnormallyonlyonelayer)、这样得吸附层被称为吉布斯单分子层

BEAConfidential、|83、2SurfactantClassificationTherearefourclassesofsurfactant,definedbytheionicnatureofthehydrophilicmoiety:anionic(阴离子型),cationic(阳离子型),non-ionic(非离子型)andzwitterionic(两性离子型)、十二酸(月桂酸)钠-肥皂十二烷基苯磺酸钠盐-洗衣粉十二烷基硫酸钠3、2SurfactantClassification溴化十六烷基三甲铵十二烷基氯化吡啶大家学习辛苦了，还是要坚持继续保持安静3、2SurfactantClassification环氧乙烷类-佰草集3、2SurfactantClassification十二烷基二甲基甜菜碱pH不敏感-完美十二烷基丙氨酸3、3Surfacetensionofsurfactantsolutions

表面活性剂溶液得表面张力Thesurfacetensionofasurfactantsolution,whenplottedagainstconcentration,usuallyfallssmoothlytoalowerlimitwhichitremainsconstant、表面活性剂溶液表面张力和浓度得变化曲线——下降后保持水平3、3Surfacetensionofsurfactantsolutions

表面活性剂溶液得表面张力ThecurveisnearlylinearatverylowconcentrationsandtheGibbsequation(吉布斯吸附方程)indicatesthattheadsorptionisthenproportionaltotheconcentration、a活度,Γ(gama)吸附量非离子型离子型1、dg/da<0,增加溶质得浓度使表面张力下降,Γ为正值,就是正吸附。表面层中溶质浓度大于本体浓度。表面活性物质属于这种情况。2、dg/da>0,增加溶质得浓度使表面张力升高,Γ为负值,就是负吸附。表面层中溶质浓度低于本体浓度。非表面活性物质属于这种情况。3、3SurfacetensionofsurfactantsolutionsWhenthesurfacetensionisplottedagainstlncthereisanearlylinearfalljustbeforeanabruptchangetotheconstantvalueofsurfacetension、若以表面张力和lnc做直线,则会在表面张力突变为定值之前有一段线性得下降区域。3、3SurfacetensionofsurfactantsolutionsTheGibbsequationshowsthatwheretheγ-lnccurveislineartheadsorptionisconstant,suggestingthattheadsorptionhasreachedalimit、Saturationadsorption3、3Surfacetensionofsurfactantsolutions吸附量得计算AdsorptionvaluescanbecalculatedfromsuchsurfacetensiondatausingtheGibbsequation、3、3Surfacetensionofsurfactantsolutions数据较少时候得两个可以得近似Atlowsurfactantconcentrationstheslopedγ/dcisnearlyconstant,andatconcentrationsjustbelowtheregionofconstantsurfacetensiontheslopedγ-lncisnealyconstant、

3、3Surfacetensionofsurfactantsolutions吸附等温线Adsorptionisotherms3、3Surfacetensionofsurfactantsolutions例题——分子截面积得求取3、3Surfacetensionofsurfactantsolutions例题——分子截面积得求取3、3Surfacetensionofsurfactantsolutions例题——分子截面积得求取3、3Surfacetensionofsurfactantsolutions例题——分子截面积得求取3、4Micelles(胶束)3、4Micelles(胶束)Asthesurfacebeescrowdedwithsurfactant,moremoleculeswillarrangeintomicelles、Atsomeconcentrationthesurfacebeespletelyloadedwithsurfactantandanyfurtheradditionsmustarrangeasmicelles、3、4Micelles(胶束)ThisconcentrationiscalledtheCriticalMicelleConcentration(CMC,临界胶束浓度)、CMC处得变化A,surfacetensionB,interfacialtensionC,osmoticpressure;D,equivalentconductivity;E,solubilityofpoundswithloworzerosolubilityinwaterCMC处得变化I-AcontinuousdecreaseinSurfaceandinterfacialtensionswithsurfactantsconcentrationuntilCMCtheSurfaceandinterfacialtensionslevelbeeconstantowingtocrowdingofsurfactantmoleculesadsorbedatsurfacesandinterfaces、A,surfacetensionB,interfacialtensionC,osmoticpressure(渗透压)D,equivalentconductivityE,solubilityofpoundswithloworzerosolubilityinwaterCMC处得变化CMC处得变化II-TheosmoticpressurerisesmuchmoreslowlywithincreasingsurfactantconcentrationabovethanitdoesbelowtheCMCbecauseitdependsonthenumberofdissolvedparticles、A,surfacetensionB,interfacialtensionC,osmoticpressureD,equivalentconductivity(当量电导)E,solubilityofpoundswithloworzerosolubilityinwaterCMC处得变化CMC处得变化III-Forionicsurfactants,theequivalentconductivitydropssharplyabovetheCMC、Onlythecounterionsofnon-associatedsurfactantmoleculescancarrycurrent、A,surfacetensionB,interfacialtensionC,osmoticpressureD,equivalentconductivityE,solubilityofpoundswithloworzerosolubilityinwaterCMC处得变化CMC处得变化IV-SolubilityofmanydrugsareincreasedafterCMC、A,surfacetensionB,interfacialtensionC,osmoticpressureD,equivalentconductivityE,solubilityofpoundswithloworzerosolubilityinwaterCMC处得变化AllthesepropertiescanbeusedtodeterminetheCMC、3、4Micelles(胶束)胶束不影响溶液表面张力3、4Micelles(胶束)胶束不影响溶液表面张力3、4Micelles(胶束)胶束得结构Hydrophilicgroupsoutwardandhydrophilicsegmentsinside3、5PropertiesofsurfactantsolutionsKrafftpoint(离子型表面活性剂)TheKrafftpointistheminimumtemperatureatwhichsurfactantsformmicelles、3、5PropertiesofsurfactantsolutionsKrafftpoint(离子型表面活性剂)TheKrafftpointistheminimumtemperatureatwhichsurfactantsformmicelles、3、5Propertiesofsurfactantsolutions您认为,如果我们需要使用胶束得话,Krafftpoint就是越高越好还就是越低越好？BEAConfidential、|45BEAConfidential、|46BEAConfidential、|47BEAConfidential、|48BEAConfidential、|49BEAConfidential、|50BEAConfidential、|513、5PropertiesofsurfactantsolutionsCloudpoint(非离子型表面活性剂)Withnon-ionicsurfactants,raisingthetemperaturedecreasesthesolubility,duetoweakeningofthehydrogenbondswithwater、Consequentlyatacertaintemperature,knownasthecloudpoint,large