研究生课件conjugated polymers

1、1,Synthesis of,-conjugated polymers,2,A Brief history,Early time: Oligomeric polyacetylene by Ziegler-Natta catalyst: the mechanism of catalyzation, cis- and trans- isomers. Intractable black powders. 1967. Shirakawa, obtained a film instead of powder by an “error” concentration of Ziegler-Natta cat

2、alyst, Ti(O-n-Bu)4/(C2H5)3Al. No increase in conductivity.,FUDAN,3,A Brief history,1970s, Halogenation by Shirakawa:,Opaque Due to very strong IR obsorption,Clear,In order to cabonization,FUDAN,4,A Brief history,1970s: MacDiarmid and Heeger: Dopping,FUDAN,5,FUDAN,6,Structures of conjugated polymers,

3、FUDAN,7,Polymerization methods: general,1. Electrochemical synthesis; self-coupling on oxidation (anodic) or reduction (cathodic); not well defined polymers. Difficult of scale up. No need for isolation and purification of polymers. 2. Lewis-acid induced; Large quantity easily; cause defects. Produc

4、ts must be isolated and reduced. 3. Ring-opening metathesis polymerization; Organometallic catalyst; high yield and high MW. 4. Transition metal catalyzed oxidative coupling.,FUDAN,8,Polyacetylenes,1. Direct polymerization of acetylene: Ziegler-Natta catalyst: Ti(O-n-Bu)4/(C2H5)3Al,Intractable polym

5、er,FUDAN,Junpo He,9,Substituted Polyacetylenes,Hagashimura and Tang BZ. Mo- and W-based catalyst,Chien JCW: copolymerization of acetylene and substituted acetylene,FUDAN,10,Cyclic Polyacetylene derivatives,By Ziegler-Natta catalyst:,FUDAN,11,Water soluble polyacetylenes,UV-Vismax = 700-800 nm Stable

6、 in air.,Thermal polymerization,FUDAN,12,From precursors by ROMP,1. Soluble; 2. High MW accessible; 3. Orientation by stretch before thermal elimination; Drawback: explosive starting materials.,Explosive !,benzvalene,FUDAN,13,Polyacetylenes from precursors,Less reactive starting materials,Precursors

7、 based on substituted cyclooctatetraene:,Conductivity depends on cis- and trans- configuration,FUDAN,14,Poly(p-phenylene),Highly crystalline, infusible, insoluble.,Friedel-Crafts:,Grignard reagent:,Byproducts: crosslinked and branched,Ullmann coupling:,Oligomers, Radical Coupling mechanism,Site cont

8、rolling,FUDAN,15,Subsitituted PPPs,Via Grignard reagent:,Via Suzuki coupling:,Via Ni(0) catalyzed coupling: TfO = trifloromethylsulfonyl,Soluble, processible but less conductivity,FUDAN,16,Soluble, fully aromatic PPPs,Hyperbranched:,FUDAN,17,Water soluble PPPs,Via Suzuki coupling:,FUDAN,18,PPPs from

9、 precursors,Poly(1,3-cyclohexadiene): drawback1,2-connection, etc.,From ester substituted PCHD:,100% 1,4-connection,FUDAN,19,Planarized PPPs,Unsubstituted PPPs: infusible, insoluble, unprocessible; Substituted: low electric conductivity.,Suzuki coupling followed by Friedel-Crafts reaction:,FUDAN,20,

10、Poly(phenylene vinylene)s (PPVs),FUDAN,Poly(arylene vinylene)s,21,Poly(phenylene vinylene),The first reported EL polymer,FUDAN,22,Poly(phenylene vinylene),The first reported EL polymer,FUDAN,23,Synthesis of PPV: the precursor routes,FUDAN,PPV is insoluble and intractable, thus usually synthesized fr

11、om poly(p-xylylene) precursors,P-quinodimethane,24,Synthesis of PPV,FUDAN,Gilch route: 1,4-bis(halomethylene)benzene,或加热300 C,25,Synthesis of PPV,FUDAN,Wessling route: the sulfonium precursors,26,Synthesis of PPV,FUDAN,Another example of Wessling route:,27,Vanderzande method,Sulfinyl and sulfonyl pr

12、ecursor:,FUDAN,28,Dithiocarbamate precursors:,Vanderzande method,FUDAN,PPV by EP and CVD,CVD:,EP: electropolymerization CVD: chemical vapor deposition,FUDAN,30,PPVs by ROMP,From precursors made by ROMP: living polymerization:,ROMP:,Block copolymer is possible: PPV-b-Poly(norbornene):,FUDAN,31,PPVs b

13、y ROMP,From precursors made by ROMP: living polymerization:,PDI= 1.2-1.3:,FUDAN,32,Acyclic diene metathesis polymerization (ADMET):,Schroks catalyst: organic tungsten (W),PPVs by ADMET,FUDAN,33,From water soluble precursors:,Water soluble PPV,FUDAN,34,Heck coupling: arylhalides and olefins,A:,B:,C:,

14、PPVs from Heck coupling,FUDAN,35,Poly(arylene ethylene)s,Different backbone structures:,PPVs from Heck coupling,FUDAN,36,PPVs by Heck coupling,An example:,Thermotropic liquid crystaline property,FUDAN,37,Wittig style polymn.:,Knovenagel reaction:,PPVs by other reactions,FUDAN,38,by 3 approaches: Ele

15、ctrochemical synthesis: Lewis acid induced polymerization: FeCl3, etc. Drawbacks: defects due to non-,-coupling, and residuals due to side reactions of catalyst, i.e. up to 45% impurities. 3. Transition metal catalyzed:,Polythiophene,FUDAN,39,Poly(alkylthiophene)s,Benefits: soluble, processible, etc

16、. Drawbacks: loss of ring symmetry, leading to Different linkage between “Head” and “Tail”. This regioirreguler is detrimental to electric conductivity.,How to prepare Poly(alkylthiophene) of high regioregularity ?,FUDAN,40,Regioregularity in Poly(alkylthiophene),FUDAN,41,Approaches: Induce differen

17、t functionalities at 2,5-positions. 1. McCullough method:,Nearly 100% HT-HT,Regioregular poly(3-alkylthiophene),FUDAN,42,Regioregular poly(3-alkylthiophene)s,2. Activated Zinc catalyst:, 98% HT-HT,Properties: random regioregular Band gap: 2.1 eV 1.7 eV Doped conductivity: 5 1350 s/cm max: x x + 20 n

18、m,FUDAN,43,Poly(3,4-ethylenedioxythiopene)(PEDOT),Bayer AG: regioregular and electron rich,Substituted PEDOTs were reported, soluble in organic solvent and water. Commercialized.,FUDAN,Regioregular poly(3-alkylthiophene)s,44,1. By Electrochemistry 2. By Stille coupling: 3. By Ullmann coupling:,Polyp

19、yrroles,FUDAN,45,Polypyrroles,Zwitterionic PPy:,In general: PPys of high molecular weight is difficult to obtain.,FUDAN,46,As early as 1862, “aniline black”, in the synthesis of organic dyes; 1960s: effect of acid on conductivity of PANI; 1980s: intensive study on conductivity: 1990s: commercialized

20、, low cost, stability. Different forms, different conductivities depend on various oxidation state.,Polyaniline,FUDAN,47,Various structures of polyaniline,Insulating state,Conducting state,FUDAN,完全还原态， 白色，不共轭，不导电,氧化掺杂态， 蓝色，半共轭，不导电,酸掺杂态， 绿色，共轭，导电,全氧化态， 绿色/紫色，不导电,48,PANI different structure,FUDAN,Emerald: 绿宝石 Emeraldine: 祖母翠绿 (苯胺氧化中间体),Leuco: 词头，表示“白色”,Nigraniline: 苯胺黑,49,Synthesis of PANI,1. E