Synthesis and characterization of poly[(methylsilylene ethynylenephenyleneethynylene)-co-(dimethylsilylene ethynylenephenyleneethynylene)]s

<正>A series of poly[(methylsilylene ethynylenephenyleneethynylene)-co-(dimethylsilylene ethynylenephenyleneethynylene)]s were synthesized by the incorporation of various ratios of methylsilylene to dimethylsilylene units into the polymer chain backbone.The resultant copolymers were soluble in a variety of common organic solvents at room temperature.The copolymers were characterized by FT-IR,~1H-NMR,GPC,rheological analysis,differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA).The results showed that the copolymers exhibited good processability and cured at low temperatures like 200℃.The curing reactions involved in hydrosilylation of Si—H and alkyne groups and the polymerization of alkynes.Y_(d5)(5%weight loss) of the cured copolymers ranged from 629℃to 686℃,and the decomposition residues of cured copolymers at 1000℃ranged from 88.1%to 90.9%under nitrogen.Thermal stability of the copolymers increased with the introduction of methylsilylene units into polymer chains.The cured copolymers were sintered at 1450℃,and the results of X-ray diffraction analysis showed that β-SiC was formed in the sintered products.     

Renewable resource‐based poly (m‐phenylenevinylene)s and their statistical copolymers: Synthesis,characterization, and probing of molecular aggregation and Forster energy transfer processes

We report a novel poly (m‐phenylenevinylene)s and their copolymers based on renewable resource starting material 3‐pentadecylphenol to trace the Forster energy transfer process and molecular aggregation in the π‐conjugated polymers. The new bisylide monomer was polymerized with bisaldehyde (or benzaldehyde) under Wittig‐Horner reaction conditions to prepare poly [(4‐methoxy‐6‐pentadecyl‐1, 3‐phenylenevinylene)‐alt‐(1, 3‐phenylenevinylene)] (m‐PPV) and its para‐counterpart poly [(4‐methoxy‐6‐pentadecyl‐1, 3‐phenylenevinylene)‐alt‐(1, 4‐phenylenevinylene)] (p‐PPV) and oligo‐phenylenevinylene model compound 4‐methoxy‐6‐pentadecyl‐1, 3‐distyrylbenzene (OPV). A series of with m‐ or p‐conjugated segments were also prepared by varying the m‐ and p‐content from 0 to 100% in the feed. The selective excitation of m‐conjugated segments in the copolymer by 310 nm light showed emission properties of pure p‐conjugated segments indicating the efficient Forster energy transfer process in segmented copolymers. Both solution quantum yields and the emission intensities increase up to 75% of para‐content in the copolymers. In the solid state, the increase in the p‐incorporation in the copolymer decreases the photoluminescent intensity almost by four times as compared to that of pure meta‐substituted PPV. The excitation spectra of the polymers confirmed a new peak at 400 nm corresponding to the aggregated polymer chains in the film, which is absent in the solution. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3241–3256, 2008     

Investigation of catalyst‐transfer condensation polymerization for synthesis of poly(p‐phenylenevinylene)

Kumada‐Tamao coupling polymerization of 1,4‐dialkoxy‐2‐bromo‐5‐(2‐chloromagnesiovinyl)benzene ( 1 ) and 1,4‐dialkoxy‐2‐(2‐bromovinyl)‐5‐chloromagnesiobenzene ( 2 ) with a Ni catalyst and Suzuki‐Miyaura coupling polymerization of 2‐{2‐[(2,5‐dialkoxy‐4‐iodophenyl)]vinyl}‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolane ( 3 ), its bromo counterpart 4 , and 2,5‐dialkoxy‐4‐(2‐bromovinyl)phenylboronic acid ( 5 ) with a Pd initiator were investigated under catalyst‐transfer condensation polymerization conditions for the synthesis of well‐defined poly(p‐phenylenevinylene) (PPV). The Kumada‐Tamao polymerization of vinyl Grignard‐type monomer 1 with Ni(dppp)Cl₂ at room temperature did not proceed, whereas aryl Grignard‐type monomer 2 afforded oligomers of low molecular weight. Matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectra of the polymer obtained from 2 implied that the Grignard end group reacted with tetrahydrofuran to terminate polymerization. On the other hand, Suzuki‐Miyaura polymerization of vinyl boronic acid ester type monomers 3 and 4 and phenylboronic acid type monomer 5 with a Pd initiator and aqueous KOH at ?20 °C to room temperature yielded the corresponding PPV with high molecular weight within a few minutes. However, the molecular weight distribution was broad, and MALDI‐TOF mass spectra showed the peaks of polymers bearing no initiator unit at the chain end, as well as those of polymers with the initiator unit. These results indicated that intermolecular chain transfer of the Pd catalyst occurred. Dehalogenation and disproportionation of the growing end also took place as side reactions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2643‐2653     

Synthesis and applications of cross-linked poly(diallyldimethyl ammonium chloride) and its derivative copolymers as efficient phase transfer catalyst for nucleophilic substitution reactions

Cross-linked poly(diallyldimethylammonium chloride) and its derivative copolymers were synthesized and used as phase transfer catalyst in the nucleophilic substitution reaction especially halogen exchange reactions. In addition, the effect of hydrophilic-hydrophobic character of the polymers in the nucleophilic reactions was investigated.     

Synthesis,magnetic, and optoelectronic properties of poly(triphenylamine‐alt‐phenylenevinylene)s

Conjugated polymers alternatively involving m‐phenylenevinylene or p‐phenylenevinylene and a triphenylamine moiety in the main chain were synthesized via a Wittig–Horner‐type polycondensation of 4‐diformyl‐4′,4″‐dimethyl‐triphenylamine or 4‐diformyl‐4′,4″‐dimethoxy‐triphenylamine with m‐xylene‐bis(diethylphosphonate) or p‐xylene‐bis(diethylphosphonate). A high glass‐transition temperature (ca. 120 °C) and thermal stability (5% weight loss at temperatures greater than 450 °C) were observed for all polymers. These polymers, especially poly(methyltriphenylamine‐alt‐p‐phenylenevinylene), fluoresced a strong green color under UV irradiation, with a quantum efficiency of 50% for their chloroform solutions. Cyclic voltammetry showed a relatively low ionization potential (5.18–5.44 eV) for the polymers. These results suggest that these polymers satisfied the requisites of polymer materials for a single‐layer light‐emitting diode. The aminium radical derived from the oxidation of poly(triphenylamine‐alt‐m‐phenylenevinylene) satisfied both non‐Kekulé‐type π conjugation and ferromagnetic connectivity of the unpaired electrons and displayed a multiplet ground state. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4119–4127, 2000     

Synthesis and characterization of polymer/clay nanocomposites by intercalated chain transfer agent

In situ synthesis of poly(methyl methacrylate) (PMMA) and polystyrene (PS) nanocomposites by free radical polymerization using intercalated chain transfer agent (I-CTA) in the layers of montmorillonite (MMT) clay is reported. MMT clay was ion-exchanged with diethyl octyl ammonium ethylmercaptan bromide, which acts both as suitable intercalant and as chain transfer agent. These modified clays were then dispersed in methyl methacrylate (MMA) or styrene (St) monomers in different loading degrees to carry out the in situ free radical polymerization. The intercalation ability of the chain transfer agent and exfoliated nanocomposite structure were evidenced by both X-ray diffraction spectroscopy (XRD) and transmission electron microscopy (TEM). Thermal properties and morphologies of the resultant nanocomposites were also studied.     

Synthesis and properties of poly(silylenevinylene(bi)phenylenevinylene)s by hydrosilylation polymerization

Poly(silylenevinylene(bi)phenylenevinylene)s were synthesized by chloroplatinic acid-catalyzed hydrosilylation polymerization between α,ω-diethynylarenes and methylphenylsilane or diphenylsilane. The polymer structure was dependent on the substituent size of silane reagent. Poly(silylenevinylenephenylenevinylene)s showed fluorescence emission in the blue region. Optical and thermal properties of the polymers were extensively investigated. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2933–2940, 1999     

相转移催化反应中界面性能的研究

过去在研究相转移催化反应机理时仅考虑在相转移催化剂作用下反应物、中间体(离子)、产物在两相间的转移,并导致两相间反应进行。我们以研究结果证明水相的表面能和两相的界面能与相转移催化反应的结果有密切关系。     

Synthesis,characterization and properties of a soluble polymer with a poly(phenylenevinylene) structure

Soluble poly(2,5-dialkoxy-1,4-phenylenevinylene) has been prepared via Stille coupling reaction between 2,5-dialkoxy-1,4-diiodobenzene and E-1,2-bis(tributylstannyl)-ethene in the presence of palladium complexes. Characterization of this material by means of ¹H and ¹³C nuclear magnetic resonance (NMR), ultraviolet/visible (UV/VIS) and infrared (IR) spectra is described. Molecular weights, determined by means of gelpermeation chromatography (GPC) analysis and referred to standard polystyrene, were in the range number-average molecular weights M _n = 2061–2544 and weight-average molecular weights M _w = 3347–3878. X-ray diffraction (XRD) analysis of the polymer showed semicrystalline structure. T_g = 57°C, transition to a stable smectic mesophase at 115°C and clearing point at 210°C were revealed by differential scanning calorimetry analysis, optical microscopy observation and XRD of the annealed polymer.     

苯基取代聚苯撑乙烯的合成及其电致发光性能

聚苯撑乙烯(PPV)类聚合物是优异的发光材料, 有望作为全色显示中三基色的材料之一得到应用. 我们采用2-溴-1,4-亚二甲苯二乙酯为原料, 合成了商品名为Supper Yellow PPV (SY PPV)的苯基取代PPV. 中间体、单体和聚合物的结构都通过核磁共振、元素分析进行了表征. SY PPV的吸收峰在434 nm, 吸收边在510 nm, 带隙2.44 eV. 光致发光峰值和电致发光峰值分别在516和552 nm. SY PPV的器件性能为: 启动电压为2.4 V, 最大亮度大于49000 cd·m^-2, 最大流明效率为21 cd·A^-1, 显著优于采用老方法合成SY PPV的最大流明效率(16-18 cd·A^-1).     

Synthesis and photovoltaic properties of poly(p‐phenylenevinylene) derivatives containing oxadiazole

A novel poly(p‐phenylenevinylene) PPV‐based copolymer (3C‐OXD‐PPV) with electron‐deficient oxadiazole segments as the side chain has been successfully synthesized through the Gilch polymerization. The obtained copolymer is soluble in common organic solvents such as chloroform, tetrahydronfuran, and 1,1,2,2‐tetrachloroethane. The copolymer was characterized by ¹H NMR, elemental analysis and GPC. TGA measurement of the copolymer shows it has good thermal stability with decomposition temperature higher than 350 °C. The absorption, electrochemical properties of the 3C‐OXD‐PPV were investigated and also compared with the properties of MEH‐PPV. The HOMO and LUMO levels of 3C‐OXD‐PPV were estimated from the electrochemical cyclic voltammograms. Bulk‐heterojunction PVCs were fabricated by using 3C‐OXD‐PPV blended PCBM as an active layer. The PCE of the PVC is 1.60% under 100 mW cm^?2 AM 1.5 illumination, which indicates that 3C‐OXD‐PPV is a potential candidate for the application of polymer PVC. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1003–1012, 2009     

Synthesis and characterization of poly[phenyl(fluoroalkyloxaalkane)silanediyl]s

Monomeric fluoroalkoxyalkyl(phenyl)dichlorosilanes were synthesized with quantitative yields by hydrosilylation of allyl ethers of fluoroalcohols with phenyldichlorosilane with Pt(Ph₃Sb)₂Cl₂ complex as a catalyst. Starting from these monomers, corresponding polysilanes with weight‐average molecular weights of 2–3 × 10⁴ were obtained by the Wurtz reaction. Increasing the CF₂ groups containing two to six monomer units caused the char yields to increase from 3 to 48% at 800 °C in air. The emission characteristics of these polysilanes in a chloroform solution were examined. They had a narrow peak at 344 nm with a small Stokes shift (≈20 nm). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3761–3767, 2003     

Synthesis of a novel rigid molecule family for the investigation of electron and energy transfer

Three new rigid bridging ligands for metal complexation (7=bmb, 8=bqb and 11=btb) were prepared from a rigid triptycene spacer connected to two bipyridine ligands using a Horner–Emmons type reaction. The triptycene spacer is substituted by methoxy groups in the case of bmb and in the case of bqb by a benzoquinone substituent. The corresponding metal complexes (ruthenium and/or osmium) were synthesised and the different luminescence behaviour was tested. They show great potential for the investigation of intramolecular electron and energy transfer reactions. The dinuclear metal complex Ru---bqb---Os is an interesting system in which the bridging ligand bqb acts as a redox switch, able to tune the conductivity for energy or electrons across the bridge.     

Synthesis and characterization of a novel hydroxypolyether blocked polydimethylsiloxane PEO-b-PDMS-b-PEO

A novel hydroxypolyether blocked polydimethylsiloxane, poly（ethylene oxide） propyl-b-polydimethylsiloxane-b-propyl poly（ethylene oxide） （PEO-b-PDMS-b-PEO） was synthesized by simple hydrosilation reaction of poly（ethylene glycol） monoallyl ether with α,ω-dihydrogen terminated PDMS （HPDMS）. Fourier transform infrared spectroscopy （FTIR） and IH NMR were used to identify the structure of PEO-b-PDMS-b-PEO and intermediate product HPDMS. Based on the effect investigations of temperature, reactant molar ratio, catalyst and time on the hydrosilation, it was found that the conversion of Si-H bond to SiC bond increased with the increase of catalyst and time, and the reaction completed when the content of catalyst was 22μg/g and the time was 5 h, respectively. Urethane reaction of OH and NCO group confirms that PEO-b-PDMS-b-PEO is more reactive toward to diisocyanate than α,ω-dihydroxylbutyl terminated PDMS.     

Synthesis of poly(arylene ethyne)s via palladium-catalyzed cross-coupling reactions with Cu and Sn reagents

Comparative studies have been carried out of the effectiveness of two organometallic coupling reagents for the synthesis of poly(alkynylarene)s via palladium catalyzed cross-coupling reactions of dialkynes with organic dibromides. In comparison to copper reagents, monomeric difunctional trialkyltin acetylides show increased thermal stability which allows reactions to be performed at higher temperatures; they give oligomeric and polymeric materials of improved molecular weight. By contrast, the inferior solubility of copper acetylides limits chain growth, and above 140°C the Pd/Cul system is prone to homopolymerization of the dialkyne. The coupling reactions are solvent-dependent but not strongly influenced by the nature of the palladium precursor complex or the phosphine ligand. © 1992 John Wiley & Sons, Inc.     

Synthesis and electrical and optoelectronic properties of poly[(N-benzyldiphenylamino)methane]

Poly[(N-benzyldiphenylamino)methane] was synthesized by the condensation polymerization of benzyldiphenylamine and formalin (30% HCOH in water) and examined for electrical and optoelectronic properties. Dark conductivity and photoconductivity of the polymer film were investigated by steady-state measurements. Current-voltage characteristics and intrinsic photoconduction of the polymer in the visible wavelength range were studied. A superlinear current increase is tentatively explained in the light of the Poole-Frenkel effect. Dielectric constant and dielectric loss parameters of the polymer are independent of frequency (50 Hz–10 kHz) and temperature (273–323 K), respectively. The growth and decay rates of the photocurrent depend on the applied voltage, and the photocurrent varies directly with the light intensity. The activation energies for dark conductivity and photoconductivity are 1.16 eV and 1.05 eV, respectively, and the optical energy band gap as evaluated from absorption coefficient spectra is 2.86 eV.     

Synthesis, excitation energy transfer and singlet oxygen photogeneration of covalently linked N-confused porphyrin-porphyrin and Zn(II) porphyrin dyads

Dyads of a N-confused porphyrin (NCP) moiety covalently linked to a porphyrin free-base (H₂P) or a zinc(II) porphyrinate (ZnP) moiety via a flexible alkyl chain of variable length have been synthesized. Photoluminescence study demonstrated an efficient excitation energy transfer from H₂P/ZnP moiety to the NCP moiety. Measurement of the near-IR emission of singlet oxygen produced by these dyads via photosensitization showed that the NCP-ZnP dyads (Ф_Δ = (0.61-0.65) ± 0.13) were better ¹O₂ generators than the NCP-P dyads (Ф_Δ = (0.36-0.41) ± 0.08).     

Synthesis and thermal properties of conjugated poly[(silylene)diacetylene silazanes]

A series of novel conjugated polymers, poly[(silylene)diacetylene silazanes] having different substituents on silicon were prepared by ammonolysis of the corresponding α,ω-dichlorodiorganosilylenediacetylene oligomers. The polymers had the number-average molecular weight between 700 and 2800, and the polydispersity index between 1.07 and 1.43. The polymers showed good solubility in common organic solvents. The structures of the poly[(silylene)diacetylene silazanes] were characterized by Fourier transform infrared, ¹H, ¹³C, ²⁹Si NMR, elemental analyses, and gel permeation chromatography. The thermal properties were measured with thermogravimetric analysis and differential scanning calorimetry. The resulting polymers had good thermal stability, and the DSC showed lower glass-transition temperature (T_g). They had good processability due to non-crystallization. Treatment of these polymers at appropriate temperature led to thermal polymerization of the acetylene unit to form a new cross-linking network system. These polymers have the potential to be used as precursors for Si/C/N-based ceramics.     

Kinetics and mechanism of the formation of poly[(1,1,3,3-tetramethyldisiloxanyl)ethylene] and poly(methyldecylsiloxane) by hydrosilylation

The kinetics of the formation of poly(carbosiloxane), as well as of alkyl-substituted poly(siloxane), by Karstedt's catalyst catalyzed hydrosilylation were investigated. Linear poly(carbosiloxane), poly[(1,1,3,3-tetramethyldisiloxanyl)ethylene], (PTMDSE), was obtained by hydrosilylation of 1,3-divinyltetramethyldisiloxane (DVTMDS) and 1,1,3,3-tetramethyldisiloxane (TMDS), while alkyl-substituted poly(siloxane), poly(methyldecylsiloxane), (PMDS), was synthesized by hydrosilylation of poly(methylhydrosiloxane) (PMHS) and 1-decene. To investigate the kinetics of PTMDSE formation, two series of experiments were performed at reaction temperatures ranging from 25 to 56 °C and with catalyst concentrations ranging from 7.0 × 10⁻⁶ to 3.1 × 10⁻⁵ mol Pt/mol CHCH₂. A series of experiments was performed at reaction temperatures ranging from 28 to 48 °C, with catalyst concentrations of 7.0 ×10⁻⁶ mol of Pt per mol of CHCH₂, when kinetics of PMDS formation was investigated. All reactions were carried out in bulk, with equimolar amounts of the reacting Si H and CHCH₂ groups. The course of the reactions was monitored by following the disappearance of the Si H bands using quantitative infrared spectroscopy. The results obtained showed typical first order kinetics for the PTMDSE formation, consistent with the proposed reaction mechanism. In the case of PMDS an induction period occurred at lower reaction temperatures, but disappeared at 44 °C and the rate of Si H conversion also started to follow the first-order kinetics. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2246–2258, 2007