The Suzuki–Miyaura coupling polymerization of dibromoarene 1 and arylenediboronic acid (ester) 2 with a Pd catalyst having a high propensity for intramolecular catalyst transfer is reported. The polymerization of excess 1 with 2 affords high‐molecular‐weight π‐conjugated polymer having boronic acid (ester) moieties at both ends, contrary to Flory's principle. This unstoichiometric polycondensation behavior is accounted for by intramolecular transfer of the Pd catalyst on 1 . In the polymerization of 1 and 2 having different aryl residues, high‐molecular‐weight polymer is obtained when the stronger donor aromatic is used as the dibromo monomer and the weaker donor or acceptor aromatic is used as diboronic acid (ester) monomer. The pinacol boronate moieties at both ends of the obtained poly(p‐phenylene) (PPP) can be converted to benzoic acid ester, hydroxyl group, and bromine. Furthermore, the reaction of the pinacol boronate‐terminated PPP with poly(3‐hexylthiophene) (P3HT) having bromine at one end yields a triblock copolymer of P3HT‐b‐PPP‐b‐P3HT.
In this study, a new electroluminescent poly(2‐decyloxy‐5‐(4′‐tert‐butylphenyl)‐1,4‐phenylene‐vinylene) (designated as DBP‐PPV) with no tolane‐bis–benzyl (TBB) structure defect was prepared by dehydrohalogenation of 1,4‐bisbromomethyl‐2‐decyloxy‐5‐(4′‐tert‐butyl‐phenyl) benzene (as monomer). The monomer bearing decyloxy and 4′‐tert‐butylphenyl substituents was synthesized via alkylation, bromination and Suzuki coupling reactions. The two asymmetric substituents of the monomer can suppress the formation of TBB defect during polymerization process and make the resultant polymer be soluble in common organic solvents. The structure and properties of DBP‐PPV were examined by 1H‐NMR, FT‐IR, UV/Vis, TGA and photoluminescence (PL) analyses. Moreover, with the DBP‐PPV acting as a light‐emitting polymer, a device with sequential lamination of ITO/PEDOT/DBP‐PPV/Ca/Ag was fabricated. The electroluminescence (EL) spectrum of the device showed a maximum emission at around 546 nm, corresponding to a yellowish‐green light. The device showed a turn‐on voltage of about 8.4 V and a maximum luminescence efficiency of 0.11 cd/A at an applied voltage of 12 V. 相似文献
1,4-Dibromo-2,5-bis(bromomethyl)benzene and benzene-2,5-dibromomethyl-1,4-bis(boronic acid propanediol diester) were used as bifunctional initiators in Atom Transfer Radical Polymerization (ATRP) of styrene or in cationic ring opening polymerization (CROP) of tetrahydrofuran in conjunction with CuBr /2,2'-bipyridine or AgSbF6, respectively. The resulting well-defined macromonomers with low polydispersities, bearing functional groups as bromine or boronic ester were used in Suzuki or Yamamoto type couplings, leading to poly(p-phenylene)s (PPPs) with polystyrene (PSt), polytetrahydrofuran (PTHF) or alternating PSt/PTHF side chains. The new polymers were characterized by GPC, 1H-NMR, 13C-NMR, IR and UV analysis. Thermal behavior of the precursors PSt or PTHF macromonomers and the final polyphenylenes were investigated by TGA and DSC analyses and compared. 相似文献
Ring‐opening polymerization of a new 1,4‐anhydro‐disaccharide monomer, 1,4‐anhydro‐2‐O‐benzyl‐3‐O‐(2,3,4,6‐tetra‐O‐benzyl‐β‐D ‐galactopyranosyl)‐α‐D ‐ribopyranose, which was prepared by the glycosylation of 1,4‐anhydro‐2‐O‐benzyl‐α‐D ‐ribopyranose with 2,3,4,6‐tetra‐O‐acetyl‐1‐O‐trichloroacetimidoyl‐α‐D ‐galactopyranose, was performed for the first time with boron trifluoride etherate to give stereoregular branched ribofuranans having high molecular weights of M̄n = 43.0×103 and positive specific rotation of [α]D25 = +25.1 deg·dm–1· g–1·cm3. The repalcement of the benzyl group by a hydroxyl group gave stereoregular 1,5‐α‐D ‐ribofuranans having a β‐D ‐galactopyranose branch in every repeating unit. The copolymerization of the ribo‐disaccharide monomer with 1,4‐anhydro‐2,3‐di‐O‐benzyl‐α‐D ‐ribopyranose was also carried out to afford stereoregular 1,5‐α‐D ‐ribofuranans having randomly distributed galactopyranose branches on the main chain. 相似文献
Summary : Four monomers; 1,4-bis(1-naphthyl) benzene ( 5 and 7 ) and 1,4-bis(2- thienyl)benzene ( 6 and 8 ) containing one or two polystyrene short chains substituted in 2 or 2, 5 positions of central phenylene ring were synthesized by Suzuki coupling reaction of two polystyrene based macromonomers ( 3 and 4 ) with 1-naphthalene- and 2-thiophene boronic acid, respectively. By chemical oxidative polymerization using FeCl3 as oxidant, copolymers containing alternating phenylene and binaphthyl ( 9 , 11 ) or phenylene and bithienyl groups ( 10 , 12 ) and polystyrene as side chains have obtained. The exact control of polystyrene branch length was performed by atom transfer radical polymerization of styrene using as initiators 1,4 dibromo-2-(bromomethyl)benzene ( 1 ) and 1,4-dibromo-2,5 di(bromomethyl)benzene ( 2 ). Polymers were characterized by FT-IR, 1H-NMR, UV and fluorescence spectroscopy and thermal methods. 相似文献
The thermal degradation of poly(p-phenylene-graft-?-caprolactone) (PPP), synthesized by Suzuki polycondensation of poly(?-caprolactone) (PCL) with a central 2,5-dibromo-1,4-benzene on the chain with 1,4-phenylene-diboronic acid, has been studied via direct pyrolysis mass spectrometry. The thermal degradation occurred mainly in two steps. In the first step, decomposition of PCL chains occurred. A slight increase in thermal stability of PCL chains was noted. In the second stage of pyrolysis, the decomposition of the polyphenylene backbone takes place. The evolution of CL monomer or small CL segments left on the phenyl ring continued also in the temperature region where degradation of PPP backbone started. 相似文献
Dimerization of 1-lithiobutadienes and 1,4-dilithiobutadienes depended remarkably on the substituents and metal halide reagents. Stereodefined multiply-substituted linear all-cis octatetraenes were prepared in moderate yields via FeCl3-mediated dimerization of 1-lithiobutadienes, while CuCl induced the dimerization of alkyl-substituted 1,4-dilithio-1,3-dienes to form linear all-cis octatetraenes and tricyclo[4.2.0.02,5]octa-3,7-dienes. Interestingly, stereodefined pentalene derivatives were also obtained when 1,4-dilithio-1,3-dienes possessed both phenyl and alkyl substituents. 相似文献
1,4-Dibromo-2,5-bis(bromomethyl)benzene was used as initiator in atom transfer radical polymerization of styrene in conjunction with CuBr/2,2′-bipyridine as catalyst. The resulting macromonomer, with a central 2,5 dibromobenzene ring and the degree of polymerization of 16 at each side, was used in combination with 2,5-dihexylbenzene-1,4-diboronic acid, for a Suzuki coupling in the presence of Pd(PPh3)4 as catalyst. The obtained polyphenylene, with alternating polystyrene and hexyl side chains, has high solubility in common organic solvents at room temperature. The new polymer was characterized by GPC, 1H-NMR, 13C-NMR, IR and UV analysis. Thermal behavior of the precursor polystyrene macromonomer and the final polyphenylene was investigated by thermogravimetric analysis and differential scanning calorimeter/calorimetry analyses and compared. 相似文献
Cationic polymerization of 2-phenylbutadiene (2-PBD) has been investigated. Polymerization were performed by SnCl4·TCA, WCl6, and BF3·OEt2 as catalysts in methylene chloride. 2-PBD polymerized easily and gave low molecular weight polymers. The polymerization proceeded to give a polymer having 1,4-structure without 1,2- or 3,4-structure. The double bonds of the polymer were partially consumed, probably owing to cyclization and chain-transfer reactions. 2-PBD was 0.66 times as reactive as styrene and 1.2 times as reactive as isoprene in the copolymerization at ?78°C by SnCl4·TCA in methylene chloride. Reactivities of ring-substituted 2-PBD obeyed the Hammett relation with ρ+ = ?2.04. The 13C chemical shift of ring-substituted 2-PBD was measured. Chemical shift values for C1 and C3 were correlated with Hammett σ, but those for C2 and C4 were almost unaffected by the substituents. On the basis of experimental results, the transition state of the cationic polymerization of 2-PBD was depicted as a benzylic cation rather than a phenylallylic one. 相似文献
A new acetylene-terminated Schiff base monomer, N,N′-(1,4-phenylenedimethylidyne)-bis-(4-ethynylaniline) (PPP), was synthesized and was characterized by nuclear magnetic resonance and infrared spectroscopy. This monomer was then polymerized to yield a new polymer (PPPP) with alternating units of aromatic imine and diacetylene via an oxidative coupling polymerization of the acetylenic terminal groups. The monomer was also polymerized by thermal curing at elevated temperatures up to 400°C to afford a crosslinked polymer network without significant structural decomposition. Thermal properties and thermal reactions of the monomer and the polymers were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymers exhibit excellent thermal stabilities in an inert atmosphere. Electronic properties of the polymers are also discussed. 相似文献
The mode of formation of isotactic and syndiotactic polymers from 1,3-dienes is examined in the light of the most recent results. An interpretation is given for the formation of trans-1,4 isotactic polymers from CH2=CH-CH=CHR (R = Me, Et, Pr, etc.) type monomers with heterogeneous VCl3-based catalysts. Evidence is reported showing that stereoregular 1,2 or cis-1,4 polymers derive from a growing polymer chain anti-η3-bonded to the transition metal and a cis-η4 coordinated monomer. The influence on stereoselectivity of the substituents at the central carbon atoms of the monomer is discussed. The peculiar behavior of (Z)-1,3-pentadiene and 4-methyl-1,3-pentadiene, which give 1,2 polymers with catalysts that give 1,4 polymers from other monomers, is attributable to the fact that they can coordinate trans-η2, in addition to cis-η4. 相似文献
A bis benzoxazine monomer with allyl groups viz: 2,2′-bis (8-allyl-3-phenyl-3,4-dihydro-2H-1,3-benzoxazinyl) propane (Bz-allyl) was synthesized via a solventless method from 2,2′diallyl bisphenol-A, paraformaldehyde and aniline. The chemical structure of Bz-allyl was confirmed by FTIR, 1H NMR and 13C NMR analyses. The monomer manifested a two-stage thermal polymerisation pattern. The first stage was attributed to the polymerisation of the allyl groups and the second to the ring - opening polymerisation of benzoxazine moiety. The polymerisation profile was investigated with DSC, FT-IR, TGA and pyrolysis-GC techniques. A polymerisation mechanism involving the electrophilic addition of the propagating iminium cation on the aniline ring in lieu of the activated sites of bisphenol-A, (which are blocked by allyl and alkyl substituents) was proposed. Additional cross-linking was provided by thermal addition polymerization of allyl groups. As a result of altered cross-linking via the aniline moiety and the additional cross-linking via allyl groups, the cured polymer exhibited a Tg of ca. 300 °C and high crosslink density. The thermal stability of this polymer was also substantially higher vis-à-vis that of the bisphenol-A based polybenzoxazine. The work focuses on the manipulation of benzoxazine monomer structure to alter the ring-opening polymerisation mechanism and cross-linking to derive polybenzoxazine with improved properties. 相似文献