The crystal structure of 1,4-benzenedithiol by rietveld analysis and studies on the mechanism of solid-state addition polymerization of 1,4-benzenedithiol to 1,4-diethynylbenzene

The crystal structure of 1,4-benzenedithiol (BDT) was determined by the Rietveld method based on the calculation of the atomic coordinates of the BDT molecule using the Molecular Mechanics Program (MMP2). The refined crystal structure of BDT was monoclinic P₂₁/c with dimensions, a = 7.795, b = 7.290, c = 5.955 Å, β = 92.16°, z = 2. The R factor of the refined structure was 0.038. Using above results, the mechanism of solid-state addition polymerization of BDT to 1,4-diethynylbenzene (DEB) was studied. Sublimed BDT piles up onto glass plate substrate and forms the layer structure along with the a axis. An inclination angle of the piled BDT column was 60° toward the substrate surface. DEB crystal structure was also monoclinic P₂₁/c with a = 4.007, b = 6.018; c = 15.340 Å, β = 91.42°, z = 2. Sublimation of equimolar mixture of BDT and DEB gave a crystal having 1 : 1 composition, in which DEB column is situated between the columns of BDT. Relative arrangement of both monomers was suitable for the addition of  SH and  CCH groups, since the distance between the two groups is 3.3 Å by CERIUS II calculation. Therefore, the addition polymerization of BDT to DEB easily proceeded by UV irradiation and the resulting polymer had a highly layer structure along with the a axis of BDT crystal. Tentatively estimated crystal structure of polymer obtained is monoclinic with a = 7.73, b = 7.30, c = 5.95 Å, β = 92.16°. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1621–1625, 1997     

Addition polymerization of 2-cyano-1, 4-benzenedithiol to 1,4-diethynylbenzene and properties of polymers

A novel addition polymerization of 2-cyano-1,4-benzenedithiol to 1,4-diethynylbenzene was carried out by UV irradiation in toluene at 50°C under nitrogen atmosphere. The polymerization proceeded readily, and a pale-yellowish conjugated polymer contain-ing sulfur atoms and cyano groups (M?_n = 20,400–80,800) was obtained in a 60–80% yield for 120–250 min. The polymer was found to be 1 : 1 alternating structure of anti-Markownikoff's type and was insolu-ble in conventional organic solvents. Since the polymer having molecular weight of the order of 10⁴ had a softening point at 115°C, a thin polymer film was obtained by heat press. TG analysis of the polymer indicated its decomposition point at about 620°C under argon atmosphere. The electrical conductivity of the polymer pellet was 10^?10 S/cm at 300 K without doping and on the order of 10^?5 S/cm on I₂ doping. Fur-thermore, the electrical conductivity of the undoped polymer pellet reversibly changed from the order of 10^?10 S/cm at 300 K to 10^?7 S/cm at 435 K with temperature variation, accompanying with increasing carrier density and mobility. The polymer pellet (M?ⁿ = 80,800) aged at 250°C for 5 min under nitrogen atmosphere exhibited the order of 10^?7 S/cm at 300 K. Thermal treatment of the polymers was thought to cause spreading of conjugated system through molecular rearrangement supported by x-ray diagrams. An absorption edge of diffuse reflectance spectra of the polymer (M?ⁿ = 80,800) was 635 nm and shifted to 880 nm by heat treatment of the polymer. © 1995 John Wiley & Sons, Inc.     

Novel conjugated polymer containing aromatic ring and selenium in backbone: Addition polymerization of 1,4-benzenediselenol to 1,4-diethynylbenzene

A novel addition polymerization of 1,4-benzenediselenol (BDSe) to 1,4-diethynylbenzene (DEB) was carried out by UV-irradiation in toluene at 60°C under nitrogen atmosphere. The polymerization proceeded at such a fast rate as to give 60–70% yield for 6 min. A paleyellowish polymer (M?_n = 20000–30000) precipitated with the progress of the polymerization. In the presence of BPO, the polymerization also proceeded rapidly to give the polymer (M?_n = 18000) in 50% yield for 4 min. The polymer was insoluble in conventional organic solvents. In the IR spectrum of the polymer, the characteristic absorption bands of cis- and trans-vinylene groups appeared at 1340 and 940 cm^?1, respectively. The microstructures of polymers were evaluated as the cis content was 90% and the trans one was 10%, based on the model adducts of benzeneselenol and ethynylbenzene. The cis ← trans isomerization occurred with UV-irradiation: the cis vinylene group of the polymer decreased from 90 to 40% for 18 h. The electrical conductivity of the polymer was in the order of 10^?13 S/cm without dopant, but increased up to 10^?5 S/cm on I₂ doping. DSC and TG thermograms of the polymer indicated its decomposition point as 465°C under nitrogen atmosphere.     

苯硫酚等离子体聚会及其结构与性能

应用外部电容耦合式等离子体聚合装置．研究了苯硫酚等离子体聚合规律，找到了最佳聚合条件，通过热失重、红外光谱、X－射线衍射、电子衍射、GC－MS和接触角测定等研究了聚合物结构与性能。电导率测定表明等离子体聚苯硫酚具有半导体性质。     

极少量1,4-戊二烯对典型Ziegler-Natta催化剂催化的丙烯聚合反应及聚丙烯性质的影响

以9,9-二(甲氧基甲基)芴(BMMF)为内给电子体的MgCl2/TiCl4催化剂与三乙基铝(TEA)组成典型Ziegler-Natta催化剂体系,催化丙烯本体聚合,考察极少量1,4-戊二烯作为共聚单体对聚合反应行为的影响.结果发现,在[1,4-戊二烯]/[丙烯]共单体摩尔比非常低(0.1%)的范围内,随着1,4-戊二烯浓度增大,催化剂活性迅速降低,[1,4-戊二烯]/[丙烯]比为0.08%时仅为约初始的1/4.但由特性黏数得到的聚合物分子量对1,4-戊二烯浓度呈现不规则变化,1,4-戊二烯并未使聚合物分子量单调降低,而在极低浓度时反而使其有所提高.凝胶渗透色谱(GPC)表征结果不但进一步确认了聚合物分子量的变化规律,还表明1,4-戊二烯并未使聚合物链发生支化.动态剪切流变测试结果显示极少量的1,4-戊二烯使聚合物的剪切黏度上升,模量提高,松弛时间延长;聚合物的拉伸黏度在拉伸流变测试中呈现相同的规律.通过1,4-戊二烯/氢气在聚合反应中协同作用的探讨,提出了对MgCl2/TiCl4/BMMF-TEA催化的丙烯/1,4-戊二烯反常共聚合行为的解释.     

二甲基苯胺等离子体聚合及聚合物结构与性能的研究

应用外部电容耦合式等离子体聚合装置，研究了二甲基苯胺等离子体聚合规律，找到了最佳的聚合条件。通过热失重，红外光谱、Ｘ－射线衍射、电子衍射和接触角测定等，研究聚合物结构与性能。电导率测定表明二甲基苯胺等离子体聚合物具有半导体性质。     

无机物表面引发聚合反应制备端接枝聚合物膜*

无机物表面引发聚合反应是聚合物合成化学的又一新领域。分子自组装技术的发展使得各种类型的聚合反应都有转移到固体表面进行的可能。本文综述了无机物表面引发聚合反应用于制备高键合密度端接枝聚合物膜的研究进展,并对其今后的发展提出了见解。     

Tetraiododiborane(4) (B2I4) is a Polymer Based on sp3 Boron in the Solid State

Herein we present the first solid‐state structures of tetraiododiborane(4) (B₂I₄), which was long believed to exist in all phases as discrete molecules with planar, tricoordinate boron atoms, like the lighter tetrahalodiboranes(4) B₂F₄, B₂Cl₄, and B₂Br₄. Single‐crystal X‐ray diffraction, solid‐state NMR, and IR measurements indicate that B₂I₄ in fact exists as two different polymeric forms in the solid state, both of which feature boron atoms in tetrahedral environments. DFT calculations are used to simulate the IR spectra of the solution and solid‐state structures, and these are compared with the experimental spectra.     

Synthesis and Structure of a New Coordination Polymer Based on Indium and 1,4-Benzenedicarboxylate

A new coordination polymer {[In(bdc)(OH)]·4H2O}n(H2bdc=1,4-benzenedi-carboxylic acid) has been synthesized through hydrothermal conditions,and was characterized by X-ray single-crystal diffraction and other measurements.The complex crystallizes in the orthorhombic system,space group Imma with a=18.3621(13),b=7.1932(5),c=11.8278(8),V=1562.24(19)3,Z=4.Dc=1.565g/cm3,Mr=368.00,F(000)=728,μ(MoKα)=1.542 mm-1,S=1.019,R=0.0468 and wR=0.1326 for 884 observed reflections(2σ(Ⅰ)).The title compound represents a 3-D framework containing four kinds of tunnels in different shapes and sizes.     

Solid-Phase Radical Polymerization of Halogen-Bond-Based Crystals and Applications to Pre-Shaped Polymer Materials

Liquid vinyl monomers were converted into solid crystals via halogen bonding. They underwent solid-phase radical polymerizations through heating at 40 °C or ultraviolet photo-irradiation (365 nm). The X-ray crystallography analysis showed the high degree of monomer alignment in the crystals. The polymerizations of the solid monomer crystals yielded polymers with high molecular weights and relatively low dispersities because of the high degree of the monomer alignment in the crystal. As a unique application of this system, the crystalized monomers were assembled to pre-determined structures, followed by solid-phase polymerization, to obtain a two-layer polymer sheet and a three-dimensional house-shaped polymer material. The two-layer sheet contained a unique asymmetric pore structure and exhibited a solvent-responsive shape memory property and may find applications to asymmetric membranes and polymer actuators.     

Electrochemical Polymerization of Brilliant Cresyl Blue and Properties of the Polymer

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Unprecedented Selectivity via Electronic Substrate Recognition in the 1,4‐Addition to Cyclic Olefins Using a Chiral Disulfoxide Rhodium Catalyst

From zero to hero? Sulfoxides are generally not considered useful ligand entities in asymmetric metal catalysis. However, a chiral disulfoxide as a chelating ligand in the rhodium‐catalyzed 1,4‐addition of aryl boronic acids to cyclic, α,β‐unsaturated ketones and esters gives impressive catalytic results, thus opening the door to future applications of this new chiral ligand class.

     

Morphology and Electrical Conductivity of Poly(N‐vinylcarbazole)/Carbon Nanotubes Nanocomposite Synthesized by Solid State Polymerization

This communication describes the morphology and DC conductivity of poly(N‐vinylcarbazole) (PNVC)/multi‐walled carbon nanotubes (MWCNTs) nanocomposite. The nanocomposite has been synthesized by solid state in situ polymerization of N‐vinylcarbazole (NVC) monomer in the presence of MWCNTs at an elevated temperature. Fourier transform infrared (FT‐IR) spectroscopy studies reveal the ability of MWCNTs to promote the in situ polymerization of the NVC monomer. Field‐emission scanning electron microscopy (FE‐SEM) observations show the homogeneous wrapping of MWCNTs' outer surface by PNVC polymer. Transmission electron microscopy (TEM) images and Raman spectroscopy results support the SEM observations. Thermogravimetric analyses reveal a significant improvement of thermal stability of the nanocomposite sample in the higher temperature region. The resulting nanocomposite material exhibits a dramatic improvement of the DC conductivity inherent to the PNVC. For example, the DC conductivity increases from ≈5.9 × 10⁻¹³ S · cm⁻¹ for PNVC to ≈12 S · cm⁻¹ for the nanocomposite, an increase of about 10¹³ in the electrical conductivity.

     

Effect of Intramolecular Transfer to Polymer on Stationary Free Radical Polymerization of Alkyl Acrylates, 2

Summary: Procedures are developed to estimate kinetic rate coefficients from available rate data for the free radical solution polymerization of butyl acrylate at 50 °C. The analysis is based upon a complete mechanistic set that includes the formation of mid‐chain radicals through backbiting and their subsequent reaction, and contains no assumptions on how the rate coefficient for cross‐termination of mid‐chain and end‐chain radicals is related to the two homo‐termination rate coefficients. After a thorough statistical analysis, the results of the fitting are combined with other recent literature data to provide a complete set of individual rate coefficients for the butyl acrylate system. Monomer addition to a mid‐chain radical is estimated to be slower than addition to a chain‐end radical by a factor of more than 400. The termination of two mid‐chain radicals is estimated to be two orders of magnitude slower than termination of two end‐chain radicals, with the cross‐termination rate coefficient close to the geometric mean.

Formation of a mid‐chain radical by intramolecular chain transfer to polymer by a chain‐end radical.     

固相二乙炴拓扑聚合及侧基效应的理论研究

用EHCO-ASED方法, 对固相二乙炔热聚合反应MDA→PBT→PDA及其侧基(R=Li、CH_3、F)效虚进行了研究。结果表明, 不同侧基的二乙炔体系的MDA—PBT—PDA变化中,在反应坐标0.86附近, 体系的能隙均达到近于零的极小值, 同时前线轨道对称性发生突变。上述变化使得此聚合反应成为热允许的。侧基的变化, 对该类反应的反应机理及活化能影响较小, 但对产物PDA的热力学稳定性的影响则较为显著。还用EHMO-ASED方法对此反应进行了计算。结果表明, 对不同侧基R, 当外推至体系重复单元数n→∞时, 都能得到与EHCO-ASED一致的结果。     

Effect of Initiator on the Incorporation of Graphite into Polymer Matrix During Suspension Polymerization

Summary: The incorporation of graphite into polystyrene (PS) particles produced by suspension polymerization was studied using a monofunctional and a bifunctional initiator, benzoyl peroxide (BPO) and 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxide) hexane (L256), respectively. The results showed that the polymerization rate was affected by graphite concentration when BPO was used as the initiator while no such effect was observed for L256. Results also showed that the incorporation of graphite in the PS particles was higher when using BPO than when using L256. Molecular weight distribution showed that during the reaction with BPO and graphite oligomers were formed indicating that the free radicals generated by the decomposition of BPO presented a very high reactivity with the functional groups present at the graphite surface while no significant effect was observed for the reaction with L256.     

Revisiting Chain Transfer to Polymer and Branching in Controlled Radical Polymerization of Butyl Acrylate

Acrylic monomers undergo chain transfer to polymer during polymerization leading to branched and even gelled polymers. It has been experimentally demonstrated that the extent of branching is higher for conventional free radical polymerization than for controlled radical polymerization (ATRP, RAFT, NMP) and this has been qualitatively explained in terms of the differences in the concentrations of highly reactive short‐chain radicals between controlled and conventional radical polymerizations. Contrary to this explanation, in this work, it is quantitatively demonstrated that the short transient lifetime of the radicals, i.e., the time between activation and deactivation of the radical in controlled radical polymerization, is the cause for the low level of branching in these polymerizations.

     

固体核磁共振弛豫在高分子研究中的应用

本文综述了近年来固体核磁弛豫方法在高分子研究中的应用，共分５个部分加以介绍：（１）自旋－晶格弛豫过程；（２）在旋转坐标系中的＾１３Ｃ自旋－晶格弛豫过程；（３）交叉极化速率和旋转坐标系中的＾１Ｈ自旋－晶格弛豫过程；（４）自旋－自旋弛豫过程；（５）动态结构导致的线形变化。本文主要讨论磁性核的各种弛豫过程以及它们与分子结构和分子运动的关系。     

(Mini)emulsion Polymerization: Effect of the Segregation Degree on Polymer Architecture

A continuous loop reactor was used for the production of 2‐ethylhexyl acrylate (2‐EHA), methyl methacrylate (MMA) and acrylic acid (AA) pressure sensitive adhesive by both emulsion and miniemulsion polymerization. Similar high monomer conversions were achieved in both processes, but striking differences in polymer architecture were found. A mathematical model was used to analyze these differences concluding that because the costabilizer suppressed monomer diffusion from miniemulsion droplets, the average polymer concentration in the polymerization loci was lower in the miniemulsion process. This resulted in less chain transfer to polymer, and hence in lower sol molecular weight and gel content.

     

引发剂结构对原子转移自由基聚合反应的影响

研究了三种不同结构的引发剂,溴代乙酸乙酯（EBrA)、α-溴代丁乙酯（EBrB)、α－溴代异丁酸乙酸（EBriB)引发的苯乙烯的原子转移自由基聚合反应（ATRP）。发现EBrA引发的苯乙烯的ATRP不是“活性”聚合。EBriB引发的苯乙烯的ATRP引发效率不够高,也不是典型的“活性”聚合。EBrB引发的苯乙烯的ATRP是较为典型的“活性”聚合：聚合物的分子量可以通过调节单体／引发剂的投料量及反应时间来控制,所得聚合物的分子量分布很窄,且有随转化率的增加而逐渐变窄的趋势。