Polymerization Of Acetylene Research Articles

Polyacetylene carbon materials: facile preparation using AlCl3 catalyst and excellent electrochemical performance for supercapacitors.

Polyacetylene (PA) was synthesized for the first time under mild conditions via polymerization of acetylene in n-octane with AlCl3 as a catalyst, whereby a series of PA-derived carbon materials were obtained. Their composition and structure were characterized and their electrochemical performance was evaluated systematically. It is found that acetylene gas at 1 MPa can polymerize explosively at room temperature under catalysis of AlCl3, forming acetylene black-like PA and a great amount of H2, while in the presence of n-octane solvent, acetylene polymerizes smoothly at higher temperature (30 to 300 °C), forming PA with a H(CH Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> CH)nH structure. A series of PA-derived carbon materials are obtained by treating PA with KOH at 800 °C. The as-synthesizzed PA-100–KOH exhibits a high specific surface area (∼2500 m2 g−1), high specific capacitance (241 F g−1 at a current density of 0.1 A g−1 and 143 F g−1 at 5 A g−1), low AC resistance, and good cycling stability with 91.7% maintenance of capacity after 2000 cycles at a current density of 2 A g−1. This paper provides a new method for the facile synthesis of PA and a novel carbon source for supercapacitor electrode materials with excellent electrochemical performance and practical application.

Enhancement of the Stability of Au-Cu/AC Acetylene Hydrochlorination Bimetallic Catalyst with Melamine Treated Support

This paper highlights the experimental and theoretical studies on the Melamine treated Active Carbon (MAC) support for an Au-Cu bimetallic catalyst in acetylene hydrochlorination reaction. Compared to the original Active Carbon (AC) loaded with the same amount of 0.1wt% Au and 1.0wt% Cu, MAC supported catalyst(MACH), wherein Carbon/C6H6N6 mass ratio was 5:3, exhibited excellent catalytic activity. The initial conversion of acetylene increased from 77.5% to 82.7% at 150℃ and atmospheric pressure. The gas hourly space velocity (GHSV) was 120h-1 under a feed volume ratio VHCl/VC2H2 of 1.05. As polymerization of acetylene on the catalyst was the main cause of deactivation, accelerated deactivation test was carried out. The result indicated MACH performed good anti-coking capacity. Based on the characterization by using BET, XRD, SEM, TGA, TPD and XPS techniques, the variation of O1s XPS spectra of the synthesized catalysts was observed that was in line with DFT results. It is postulated that the better stability and the better dispersion of gold actions were ascribed to the additional metal and the modified substrate. The electron transmission from the auxiliary and the elevated groups on the catalyst surface partially inhibited the reduction of the Au3+ active species. Meanwhile, the stronger adsorption energy of HCl was also beneficial to catalytic activity and stability.

Synthesis and Characterization of a Molybdenum Alkylidyne Supported by a Trianionic OCO3– Pincer Ligand

This report details the preparation of the trianionic pincer ligand supported Mo–alkylidyne complex [tBuOCO]Mo≡CMes(THF)2 (5). The catalytic activity of [tBuOCO]Mo≡CMes(THF)2 (5) for alkyne polymerization is limited in contrast to its W-congener. Solution and crystallographic evidence for the conversion of the trianionic pincer complex [tBuOCO]Mo≡CMes(THF)2 (5) to a tetraanionic pincer complex [O2C(MesC═)Mo(η2-CH≡CtBu)(THF)] (6) upon exposure to tert-butylacetylene is provided.

Multicomponent Polymerization of Alkynes, Sulfonyl Azide, and Iminophosphorane at Room Temperature for the Synthesis of Hyperbranched Poly(phosphorus amidine)s

The construction of functional hyperbranched polymers with unique topological structures and distinct properties remains a great challenge. Multicomponent polymerization, as a fascinating polymer synthetic approach, has proved to be a powerful tool for the synthesis of polymers with diverse structures and multifunctionalities, which is a great advantage for the preparation of hyperbranched polymers. In this work, a multicomponent polymerization of alkynes, sulfonyl azide, and iminophosphorane is utilized for the construction of heteroatom-rich hyperbranched poly(phosphorus amidine)s with different topological structures and fluorescence response toward platinum group metal ions.

Cooperative Behavior in the Evolution of Alignment and Structure in Vertically Aligned Carbon-Nanotube Arrays Grown using Chemical Vapor Deposition

A great obstacle to technology using ``forests'' of highly ordered, vertically aligned carbon nanotubes (CNTs) is that collective properties of forests are inferior to those of individually grown freestanding CNTs. The pattern of changing growth rates seen in real-time measurements reveals that the carbon incorporation driving forest growth is governed by autocatalytic radical-chain polymerization of acetylene. Considering CNTs as a type of polymer renders the established methods of polymer science relevant for optimizing macroscopic platforms to retain the superior properties of individual CNTs in high-density energy storage, rapid heat dissipation, and advanced interconnects.

Molecular Dynamics Simulations of Hydrocarbon Film Growth from Acetylene Monomers and Radicals: Effect of Substrate Temperature

In an attempt to rationalize the mechanisms occurring during plasma polymerization of acetylene, classical molecular dynamics computer simulations investigating the deposition and reaction of a mixed gas of acetylene molecules and radicals on the Ag(111) substrate were performed for a wide range of substrate temperatures. Prior to that, this article establishes a methodology for film deposition and identifies the appropriate potentials for hydrocarbons by comparison with electronic calculations using density functional theory. On the basis of this preliminary study, simulations of film growth are carried out at different temperatures using the reactive empirical bond order potential. Our results show that the rates of formation of new C–C and C–H bonds are higher at the beginning of the film growth when the substrate is still exposed than when it is covered with polymeric chains, and these initial reaction rates are proportional to temperature. The analysis of the hybridization of carbon atoms in the film...

Regio- and Stereoselective Polymerization of Diynes with Inorganic Comonomer: A Facile Strategy to Conjugated Poly(p-arylene dihalodiene)s with Processability and Postfunctionalizability

Development of new methodologies for synthesizing polymers with novel structures and unique properties is a fundamentally important area in polymer science. Herein, a novel synthetic strategy to conjugated poly(p-arylene dihalodiene)s (PADs) with high regio- and stereoselectivity was developed. In the presence of PdBr2 and CuBr2, the polymerizations of terminal alkynes proceeded smoothly in air without heating to generate PADs in high yields (up to 95.3%) with high molecular weights (Mw up to 915 900). Low-cost inorganic CuBr2 played dual roles as cocatalyst and comonomer. The PADs possessed good solubility and film-forming ability. Their thin films exhibited high refractive indices (1.7149–1.7245) and would be fabricated into well-resolved fluorescent photopatterns by photolithography. Thanks to the vinyl bromine functionality, the PADs could undergo efficient postmodification to afford polymers with more sophisticated structures and applications.

Nanocage-Confined Synthesis of Fluorescent Polycyclic Aromatic Hydrocarbons in Zeolite.

Polycyclic aromatic hydrocarbons (PAHs) attract much attention for applications to organic light-emitting diodes, field-effect transistors, and photovoltaic cells. The current synthetic approaches to PAHs involve high-temperature flash pyrolysis or complicated step-by-step organic reactions, which lead to low yields of PAHs. Herein, we report a facile and scalable synthesis of PAHs, which is carried out simply by flowing acetylene gas into zeolite under mild heating, typically at 400 °C and generates the products of 0.30 g g-1 zeolite. PAHs are synthesized via acetylene polymerization inside Ca2+-ion-exchanged Linde type A (LTA) zeolite, of which the α-cage puts a limit on the product molecular size as a confined-space nanoreactor. The resultant product after the removal of the zeolite framework exhibits brilliant white fluorescence emission in N-methylpyrrolidone solution. The product is separated into four different color emitters (violet, blue, green, and orange) by column chromatography. Detailed characterizations of the products by means of various spectroscopic methods and mainly mass spectrometric analyses indicate that coronene (C24H12) is the main component of the blue emitter, while the green emitter is a mixture of planar and curved PAHs. The orange can be attributed to curved PAHs larger than ovalene, and the violet to smaller molecules than coronene. The PAH growth mechanism inside Ca2+-exchanged LTA zeolite is proposed on the basis of mass spectral analyses and density functional theory calculations.

Direct Polymerization of Carbon Dioxide, Diynes, and Alkyl Dihalides under Mild Reaction Conditions

Fixing carbon dioxide (CO2) into useful polymeric materials has attracted broad interest since carbon dioxide is an abundant, inexpensive, nontoxic, and renewable C1 resource. Nevertheless, the polymerization of CO2 and alkynes attracted less attention because the propagation step involving CO2 is a major obstacle. Herein, we overcome this obstacle by developing a facile and efficient Ag2WO4-catalyzed polymerization of CO2, diynes, and alkyl dihalides under mild reaction conditions. Soluble and thermally stable poly(alkynoate)s with high weight-average molecular weights (up to 31 400) were obtained in high yields (up to 95%). Thanks to its unique reaction mechanism, this step-growth polymerization can produce an ethynyl group terminated telechelic polymer that can be used as macromonomer to prepare poly(alkynoate)s with higher molecular weights by either continually adding alkyl dihalide into the reaction solution or mixing the isolated telechelic polymers with alkyl dihalide and catalytic system under a ...

Synthesis of Functional Poly(propargyl imine)s by Multicomponent Polymerizations of Bromoarenes, Isonitriles, and Alkynes.

Here we reported a versatile and multicomponent polymerization (MCP) approach that enabled the synthesis of functional poly(propargyl imine)s with well-defined structures and high molecular weight (Mw up to 38 200) in excellent yields (up to 93%) from readily accessible monomers of dibromoarenes, isonitriles, and diynes. This MCP had the advantages of simple operation, wide substrate scope, and mild reaction conditions. The resulting polymers possessed good solubility and showed high thermal stability and refractive indices. The tetraphenylethene-containing polymer displayed a phenomenon of aggregation-induced emission and could respond to various acidic vapors.

Epoxy resins toughened with in situ azide–alkyne polymerized polysulfones

ABSTRACTTo simultaneously improve the fracture toughness and heat resistance of a cured toughened epoxy resin along with a reduction in its viscosity during the mixing process, two novel polysulfone‐type polymers are synthesized via azide–alkyne polymerization for use as toughening agents. The epoxy resin toughened with these polymers by in situ azide–alkyne polymerization during the cure process, which shows excellent processibility and based on the significantly lower viscosity (61 and 62 cP) during epoxy mixing process than that of commonly commercial polyethersulfone (PES, 127,612 cP). The novel polysulfone‐type polymer toughened epoxy resin showed the advantage in excellent fracture toughness than the PES toughened epoxy. In addition, the glass transition temperature of the novel polysulfone‐type polymer toughened epoxy resin is similar to that of the neat one (∼230 °C) and does not decrease, which implies excellent heat resistance of the toughened epoxy. These phenomena can be attributed to the formation of semi‐interpenetrating polymer networks comprising the epoxy network and the linear polysulfone‐type polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45790.

Graphene Oxide (GO) as Stabilizer for Preparing Chirally Helical Polyacetylene/GO Hybrid Microspheres via Suspension Polymerization.

Hybrid materials consisting of polymers and graphene are gathering ever-growing interest. This article reports a novel methodology for preparing chirally helical polyacetylene/graphene hybrid microspheres (MPs) via suspension polymerization in which graphene oxide (GO) or alkynylated GO (MGO) serves as a sole stabilizer. Such polymerizations show remarkable advantages in circumventing the difficulties in usual suspension polymerizations and especially in directly providing clean hybrid MPs. Scanning electron microscopy (SEM), Raman spectra, and electron dispersive spectroscopy indicate that graphene sheets cover the MPs through physical interaction (GO) or covalent bonds (MGO). The hybrid MPs are also characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy, and thermogravimetric analysis. Circular dichroism spectra demonstrate that the polymer chains constituting the MPs adopt predominantly one-handed helices, endowing the MPs with intriguing optical activity. The established strategy opens a new approach for preparing hybrid MPs constructed by acetylenic polymers and GO.

Polycouplings of Alkynyl Bromides and Sulfonamides toward Poly(ynesulfonamide)s with Stable Csp–N Bonds

The development of new polymerization methodology is crucial for polymer materials. Alkyne polymerization based on versatile reactions of C≡C bonds have attracted much attention recently because they can produce a great diversity of polymer materials with unsaturated structures and potential semiconducting properties. Among that, the polymerizations between alkyne and amine/amide which afford nitrogen-substituted alkynes with the triple bonds strongly polarized by the nitrogen atoms are quite attractive but challenging. In this work, the polycoupling of alkynyl bromides and sulfonamides is reported as the first example to generate polymers with stable N–C≡C bonds in the polymer main chain. The polycoupling of various aromatic/aliphatic alkynyl bromides and sulfonamides can be carried out at mild condition in the presence of CuSO4·5H2O, 1,10-phenanthroline, and K2CO3 at 65 °C under nitrogen, affording poly(ynesulfonamide)s with high molecular weights (up to 22 000 g/mol) in high yields (up to 95%). Incorpo...

Recent New Methodologies for Acetylenic Polymers with Advanced Functionalities

Polymers synthesized from acetylenic monomers often possess electronically unsaturated fused rings and thus show versatile optoelectronic properties and advanced functionalities. To expand the family of acetylenic polymers, development of new catalyst systems and synthetic routes is critically important. We summarize herein recent research progress on development of new methodologies towards functional polymers using alkyne building blocks since 2014. The polymerizations are categorized by the number of monomer components, namely homopolymerizations, two-component polymerizations, and multicomponent polymerizations. The properties and applications of acetylenic polymers, such as aggregation-induced emission, fluorescent photopatterning, light refraction, chemosensing, mechanochromism, chain helicity, etc., are also discussed.

Plasma polymerized acetylene deposition using a return corona enhanced plasma reactor

A corona based weakly ionized plasma source was developed to deposit plasma polymerized acetylene coating at atmospheric pressure. The plasma source included a distinctive point-to-point geometry consisting of an array of high voltage needles and an array of protrusions placed over a grounded screen. The geometry facilitated various corona discharge modes that included return corona to contribute plasma polymerized acetylene deposition downstream from the corona section. Scanning probe techniques were used to investigate deposition on both the leading surface and the trailing surface of substrates. Deposition was initiated as distinct nodules that merged to form a thin plasma polymerized coating.

Pressure‐Induced Polymerization of Acetylene: Structure‐Directed Stereoselectivity and a Possible Route to Graphane

Geometric isomerism in polyacetylene is a basic concept in chemistry textbooks. Polymerization to cis-isomer is kinetically preferred at low temperature, not only in the classic catalytic reaction in solution but also, unexpectedly, in the crystalline phase when it is driven by external pressure without a catalyst. Until now, no perfect reaction route has been proposed for this pressure-induced polymerization. Using in situ neutron diffraction and meta-dynamic simulation, we discovered that under high pressure, acetylene molecules react along a specific crystallographic direction that is perpendicular to those previously proposed. Following this route produces a pure cis-isomer and more surprisingly, predicts that graphane is the final product. Experimentally, polycyclic polymers with a layered structure were identified in the recovered product by solid-state nuclear magnetic resonance and neutron pair distribution functions, which indicates the possibility of synthesizing graphane under high pressure.

Pressure‐Induced Polymerization of Acetylene: Structure‐Directed Stereoselectivity and a Possible Route to Graphane

AbstractGeometric isomerism in polyacetylene is a basic concept in chemistry textbooks. Polymerization to cis‐isomer is kinetically preferred at low temperature, not only in the classic catalytic reaction in solution but also, unexpectedly, in the crystalline phase when it is driven by external pressure without a catalyst. Until now, no perfect reaction route has been proposed for this pressure‐induced polymerization. Using in situ neutron diffraction and meta‐dynamic simulation, we discovered that under high pressure, acetylene molecules react along a specific crystallographic direction that is perpendicular to those previously proposed. Following this route produces a pure cis‐isomer and more surprisingly, predicts that graphane is the final product. Experimentally, polycyclic polymers with a layered structure were identified in the recovered product by solid‐state nuclear magnetic resonance and neutron pair distribution functions, which indicates the possibility of synthesizing graphane under high pressure.

The growth of carbon chains in IRC +10216 mapped with ALMA.

Linear carbon chains are common in various types of astronomical molecular sources. Possible formation mechanisms involve both bottom-up and top-down routes. We have carried out a combined observational and modeling study of the formation of carbon chains in the C-star envelope IRC +10216, where the polymerization of acetylene and hydrogen cyanide induced by ultraviolet photons can drive the formation of linear carbon chains of increasing length. We have used ALMA to map the emission of λ 3 mm rotational lines of the hydrocarbon radicals C2H, C4H, and C6H, and the CN-containing species CN, C3N, HC3N, and HC5N with an angular resolution of ~1″. The spatial distribution of all these species is a hollow, 5-10″ wide, spherical shell located at a radius of 10-20″ from the star, with no appreciable emission close to the star. Our observations resolve the broad shell of carbon chains into thinner sub-shells which are 1-2″ wide and not fully concentric, indicating that the mass loss process has been discontinuous and not fully isotropic. The radial distributions of the species mapped reveal subtle differences: while the hydrocarbon radicals have very similar radial distributions, the CN-containing species show more diverse distributions, with HC3N appearing earlier in the expansion and the radical CN extending later than the rest of the species. The observed morphology can be rationalized by a chemical model in which the growth of polyynes is mainly produced by rapid gas-phase chemical reactions of C2H and C4H radicals with unsaturated hydrocarbons, while cyanopolyynes are mainly formed from polyynes in gas-phase reactions with CN and C3N radicals.

Metal-Free Multicomponent Tandem Polymerizations of Alkynes, Amines, and Formaldehyde toward Structure- and Sequence-Controlled Luminescent Polyheterocycles

Sequence-controlled polymers, including biopolymers such as DNA, RNA, and proteins, have attracted much attention recently because of their sequence-dependent functionalities. The development of an efficient synthetic approach for non-natural sequence-controlled polymers is hence of great importance. Multicomponent polymerizations (MCPs) as a powerful and popular synthetic approach for functional polymers with great structural diversity have been demonstrated to be a promising tool for the synthesis of sequence-controlled polymers. In this work, we developed a facile metal-free one-pot multicomponent tandem polymerization (MCTP) of activated internal alkynes, aromatic diamines, and formaldehyde to successfully synthesize structural-regulated and sequence-controlled polyheterocycles with high molecular weights (up to 69 800 g/mol) in high yields (up to 99%). Through such MCTP, polymers with the in situ generated multisubstituted tetrahydropyrimidines or dihydropyrrolones in the backbone and inherent luminescence can be easily obtained with high atom economy and environmental benefit, which is inaccessible by other synthetic approaches.

Polymerization of optically active disubstituted acetylene monomers by Pd catalyst bearing bulky phosphine ligand

ABSTRACTChloro‐ and aryl‐substituted acetylene monomers having an optically active group were polymerized by a Pd catalyst [(tBu3P)PdMeCl] bearing a bulky phosphine ligand, and by MoCl5 for comparison. The corresponding disubstituted acetylene polymers with Mn's = 2000–19,500 and 6900–10,800 were obtained in 29–83% and 11–62% yields when the Pd and Mo catalysts were used, respectively. The formation of polyacetylenes, poly[(R)‐1p], poly[(R)‐1m], and poly[(S)‐2p] were confirmed by SEC and the presence of a Raman scattering peak based on the alternating double bonds of the main chain. Pd‐based poly[(R)‐1m] exhibited CD signals around 350 nm assignable to a certain secondary structure, while Mo‐based poly[(R)‐1m] did not. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3011–3016