活性自由基英文文献总结.pptx
- 文档编号:18743320
- 上传时间:2023-10-26
- 格式:PPTX
- 页数:11
- 大小:195.92KB
活性自由基英文文献总结.pptx
《活性自由基英文文献总结.pptx》由会员分享,可在线阅读,更多相关《活性自由基英文文献总结.pptx(11页珍藏版)》请在冰点文库上搜索。
FreeRadicalPolymerization,RadicalPolymerization,Hightoleranceofgrowingradicalspeciestowardmanyfunctionalgroups,Copolymerizationsbetweenvariousmonomersarequitestraightforwardandhighmolecularweightpolymersareformedearly,Radicalpolymerizationcanbecarriedoutinawiderangeoftemperaturesandconditions,Architecturalcontrol,IonicPolymerization,combinetheadvantages,ControlledRadicalPolymerization,F.diLena,K.Matyjaszewski/ProgressinPolymerScience35(2010)9591021,FreeRadicalPolymerization,ControlledRadicalPolymerization,(i)Therateofinitiationisfasterthanthatofpropagation,sothatallchainsformandgrowsimultaneously.(ii)Theconcentrationofactiveradicalsislowinordertoslowdownterminationreactions.(iii)Theconcentrationofpropagatingchainsishighsoonlyasmallfractionofthemareterminated.(iv)Thepolymerizationsystemremainssufficientlyhomogeneous,sothattheactivecentersarereadilyavailable.,requirements,F.diLena,K.Matyjaszewski/ProgressinPolymerScience35(2010)9591021,Organometallicmediatedradicalpolymerization,isbasedonthefastandreversiblehomolyticcleavageofametal-carbonbondinthemetalcomplex.Dependingonthetypeofmonomerused,thespecificmetal/ligandcombinationandtheinitiationstrategy,OMRPcanoccurthrougheitherRDCorDTorbothmechanisms.Chain-breakingreactionssuchasCCTmayalsocompetitivelytakeplace.,F.diLena,K.Matyjaszewski/ProgressinPolymerScience35(2010)9591021,TransitionmetalcomplexesthathavebeenreportedtopolymerizeolefinsviaaRDCmechanismincludeTi,Mo,Os,Co,andRhcompounds.,reversibledeactivationbycoupling(RDC)mechanism,F.diLena,K.Matyjaszewski/ProgressinPolymerScience35(2010)9591021,Catalyticchaintransfer(CCT),whenitsrateissufficientlyhigh,themolecularweightdistributionoftheresultingoligomerscanbedescribedbyaShultzFlorystatistics(Mw/Mn2).EfficientCCThasbeenreportedwithcertainMo,Fe,andespeciallyCocomplexes.,F.diLena,K.Matyjaszewski/ProgressinPolymerScience35(2010)9591021,Catalyticchaintransfer(CCT)process,Degenerativetransfer(DT)process,F.diLena,K.Matyjaszewski/ProgressinPolymerScience35(2010)9591021,Themethodisknownasdegenerativetransfer(DT)radicalpolymerization.Theexchangeprocessusuallytakesplacethroughashort-livedintermediatethatinsomecasescanbeconsideredatransitionstate.,SincetheCoCbondcleavageofOrgano-cobalt(III)complexescanbeachievedundermildconditions,organocobaltcomplexeshavebeenusedassourcesofcarbon-centeredradicalsfororganicsynthesisandinpolymerchemistry.,A.Debuigneetal./ProgressinPolymerScience34(2009)211239,Additionof(TMP)CoIIreducestherateofpolymerization,andthepoly-merizationprocesscanbeeffectivelystoppedandrestartedrepetitivelybycyclingthereactiontemperaturebetween5and60.AlinearincreaseinMnwithMAconversionalongwithrelativelysmallPMApolydispersities(Mw/Mn=1.1-1.2)indicatesthatapreponderanceofthepolymerchainsaregrowinginamannercharacteristicofalivingpolymerizationprocess.,(TMP)Co-CH2C-(CH3)31,(TMP)Co-MA2,Reactionof2withMAat60inbenzeneresultsinformationofPMAwithrelativelysmallpolydispersity(1.1-1.3)andlinearincreaseinMn(1X104to1.7X105)withMAconversion(5-80%,DP=125-2000).,Inspiteoftheprocessesthatcanlimitpolymergrowth,observationoflinearincreasesinMnwithconversion,formationofblockcopolymers,andrelativelysmallpolydisper-sitiesclearlydemonstratethat1and2initiateaneffectivelivingradicalpolymerizationofacrylates.,BradfordB.Wayland/J.Am.Chem.SOC.1994,116,7943-7944,In2004,theWaylandresearchgroupshowedthat,inthepresenceofaradicalsourcesuchasAIBNorV-70,thepolymerizationofMAcouldbemediatedbycatalyticamountsof(TMP)Co.At60Candinbenzene,afterashortinductionperiod,PMAofmolecularweightupto120,000andpolydispersityaslowas1.06wereproduced.Lowpolydispersitypoly(MA-b-BA)copolymerswerealsoefficientlysynthesized.,Mechanism,(i)theinductioncorrespondstothetimerequiredtoproducesufficientradicalstoconvertalloftheCo(II)speciesintoCo(III)R,whichcontrolsthepolymerizationviaaslowRDCmechanism.(ii)ThecontinuedinfluxofradicalsfromV-70changestheprocesstoafasterDT-basedpolymerizationinwhichbothln(M0/M)vs.timeandMnvs.conversionincreaselinearly.(iii)AftertheinfluxofnewradicalsfromV-70hasended,thepolymer-izationreactionrevertstotheslowerRDCpathway.,F.diLena,K.Matyjaszewski/ProgressinPolymerScience35(2010)9591021,Theaccuracyoftheoreticalcalculationsintermsofmolecularstructure,energeticsandphysicalpropertieshasmadeenormousprogressinthelastcoupleofdecades.Theapplicationofcomputationaltools,especiallyDensityFunctionalTheory(DFT)methods,inviewoftheirrelativelygoodperformanceatcomparativelylowcomputationalcost,isbecomingroutineinavarietyofdifferentareasofchemistryandcontrolledradicalpolymerizationisnoexception.,A.Debuigneetal./ProgressinPolymerScience34(2009)211239,
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 活性 自由基 英文 文献 总结
![提示](https://static.bingdoc.com/images/bang_tan.gif)