Electrogeneration of Conducting Poly(α-tetrathiophene). Effect of Solution Stirring and Detection of Linear Oligomers

2003 ◽  
Vol 68 (7) ◽  
pp. 1326-1344 ◽  
Author(s):  
Francesc Estrany ◽  
Ramon Oliver ◽  
Esther García ◽  
Esther Gualba ◽  
Pere-Lluís Cabot ◽  
...  
Keyword(s):  
Ion Pairs ◽  
Polymer Chains ◽  
Polymerization Process ◽  
Anodic Process ◽  
Cathodic Peak ◽  
Linear Chains ◽  
Monomer Solution ◽  
Ir Analysis ◽  
Microscopy Images ◽  
Tof Ms

The anodic oxidation of α-tetrathiophene on Pt was studied in a 1.0 mM monomer solution in 0.1 M LiClO4 in 45:35:20 acetonitrile/ethanol/DMF. Three consecutive oxidation peaks were detected by cyclic voltammetry, along with a cathodic peak related to the reduction of electroactive polarons formed during the first anodic process. Uniform, adherent, insoluble and black polymer films were obtained by chronoamperometry at 1.000 V vs Ag|AgCl corresponding to the first oxidation-polymerization process. Stirring of monomer solution promotes the production of polymer, favoring the oxidation of polymer chains with the incorporation of more doping ClO4- ions and ion pairs of Li+ClO4- in their monomeric units. The conductivity of the polymer obtained under stirring was three orders of magnitude higher than that synthesized from a quiescent solution. The scanning electron microscopy images also showed much more uniform films under stirring. This behavior points to the existence of less crosslinking in the polymer and the production of longer linear chains when the solution is stirred. IR analysis of these materials confirmed the formation of crosslinked chains with predominance of β-β linkages. Short linear oligomers such as the dimer, trimer and tetramer were detected in all polymers by MALDI-TOF-MS, thus showing a radical polycondensation as initial electropolymerization mechanism. A larger proportion of linear oligomers is formed under solution stirring.

Dynamics of Ion Locking in Doubly Polymerized Ionic Liquids

2020 ◽  
Author(s):  
Swati Arora ◽  
Julisa Rozon ◽  
Jennifer Laaser
Keyword(s):  
Dielectric Constant ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Ion Pairs ◽  
Polymer Chains ◽  
Ion Motion ◽  
Charged Species ◽  
Broadband Dielectric Spectroscopy ◽  
Covalently Linked ◽  
Insight Into

<div>In this work, we investigate the dynamics of ion motion in “doubly-polymerized” ionic liquids (DPILs) in which both charged species of an ionic liquid are covalently linked to the same polymer chains. Broadband dielectric spectroscopy is used to characterize these materials over a broad frequency and temperature range, and their behavior is compared to that of conventional “singly-polymerized” ionic liquids (SPILs) in which only one of the charged species is attached to the polymer chains. Polymerization of the DPIL decreases the bulk ionic conductivity by four orders of magnitude relative to both SPILs. The timescales for local ionic rearrangement are similarly found to be approximately four orders of magnitude slower in the DPILs than in the SPILs, and the DPILs also have a lower static dielectric constant. These results suggest that copolymerization of the ionic monomers affects ion motion on both the bulk and the local scales, with ion pairs serving to form strong physical crosslinks between the polymer chains. This study provides quantitative insight into the energetics and timescales of ion motion that drive the phenomenon of “ion locking” currently under investigation for new classes of organic electronics.</div>

scholarly journals Homogeneous Distribution of Polymerizable Coumarin Dyes for Active Few Mode POF

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1975
Author(s):  
Florian Jakobs ◽  
Kristoffer Harms ◽  
Jana Kielhorn ◽  
Daniel Zaremba ◽  
Pen Yiao Ang ◽  
...  
Keyword(s):  
Methyl Methacrylate ◽  
Optical Fibers ◽  
High Performance ◽  
Polymer Chains ◽  
Size Exclusion ◽  
Polymerization Process ◽  
Homogeneous Distribution ◽  
Exclusion Chromatography ◽  
Polymer Optical Fibers ◽  
Coumarin Dyes

For most kinds of active polymer optical fibers, a homogeneous distribution of dye molecules over the entire fiber length and cross section is required. In this study, chemical bonding of dyes to poly(methyl methacrylate) (PMMA) by copolymerization is achieved within the polymerization process instead of dissolving the dyes in the monomers. In combination with an improved fabrication mechanism, this leads to homogeneous dye distribution within the preforms. A method for proving the integration of the dyes into the polymer chains has been developed using high-performance liquid chromatography (HPLC) and size exclusion chromatography (SEC). Prestructured core-cladding preforms with dye-doped poly(cylohexyl methacrylate-co-methyl methacrylate)-core have been prepared with the Teflon string technique and were heat-drawn to few mode fibers.

scholarly journals Synthesis and Characterization of a Lignin-Styrene-Butyl Acrylate Based Composite

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1080
Author(s):  
Daniel López Serna ◽  
Perla Elizondo Martínez ◽  
Miguel Ángel Reyes González ◽  
Antonio Alberto Zaldívar Cadena ◽  
Erasto Armando Zaragoza Contreras ◽  
...  
Keyword(s):  
Contact Angle ◽  
Butyl Acrylate ◽  
Raw Materials ◽  
Positive Influence ◽  
Polymer Chains ◽  
Polymer Materials ◽  
Polymerization Process ◽  
Oh Groups ◽  
Water Measurement

In recent years, the pursuit of new polymer materials based on renewable raw materials has been intensified with the aim of reusing waste materials in sustainable processes. The synthesis of a lignin, styrene, and butyl acrylate based composite was carried out by a mass polymerization process. A series of four composites were prepared by varying the amount of lignin in 5, 10, 15, and 20 wt.% keeping the content of butyl acrylate constant (14 wt.%). FTIR and SEM revealed that the –OH functional groups of lignin reacted with styrene, which was observed by the incorporation of lignin in the copolymer. Additionally, DSC analysis showed that the increment in lignin loading in the composite had a positive influence on thermal stability. Likewise, Shore D hardness assays exhibited an increase from 25 to 69 when 5 and 20 wt.% lignin was used respectively. In this same sense, the contact angle (water) measurement showed that the LEBA15 and LEBA20 composites presented hydrophobic properties (whit contact angle above 90°) despite having the highest amount of lignin, demonstrating that the interaction of the polymer chains with the –OH groups of lignin was the main mechanism in the composites interaction.

Gaussian analysis of Raman spectroscopy of acetic acid reveals a significant amount of monomers that effectively cooperate with hydrogen bonded linear chains

2014 ◽  
Vol 16 (41) ◽  
pp. 22458-22461 ◽  
Author(s):  
Jianping Wu
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Acetic Acid ◽  
Polymer Chains ◽  
Linear Chains ◽  
Gaussian Analysis ◽  
Hydrogen Bonded

Gaussian analysis of Raman spectroscopy reveals three hydrogen bonding structures in the liquid acetic acid (AA): linear chains, cyclic dimers and dissociated monomers that effectively cooperate with hydrogen bonded stacks of linear AA or polymer chains.

Cis-Trans Isomerization of Natural Rubber under the Influence of Organo-Aluminum Compounds and Titanium Tetrachloride

1959 ◽  
Vol 32 (4) ◽  
pp. 1036-1038 ◽  
Author(s):  
B. A. Dolgoplosk ◽  
E. N. Kropacheva ◽  
K. V. Nelson
Keyword(s):  
Natural Rubber ◽  
Ultraviolet Light ◽  
Titanium Tetrachloride ◽  
Chemical Properties ◽  
Regular Structure ◽  
Polymer Chains ◽  
Polymerization Process ◽  
Aluminum Compounds ◽  
Physical And Chemical ◽  
First Time

Abstract Ziegler catalysts have become of prime importance for synthesis of polymers with regular structure, particularly cis-polyisoprene. The disruption of the structure of the chain by the formation of trans units was, until now, connected only with the influence of the physical and chemical properties of the catalyst on the nature of the addition of the diene monomers during the polymerization process. In the present work it is shown that destruction of regularity of structure can be caused by isomerization of cis units in complete polymer chains into trans units under the influence of the compounds used for initiating the polymerization process. Attempts to isomerize natural rubber by means of ultraviolet light and iodine did not give the expected effect. Ferri established for the first time that under the influence of zinc chloride and titanium tetrachloride natural rubber undergoes changes accompanied by disappearence of crystallization on stretching as shown by x-ray structure analysis. On the basis of these results the authors presumed that under the influence of these agents isomerization of cis units to trans units occurs in the natural rubber chain. The isomerization of cis-1,4 units to trans units in polybutadiene by means of ultraviolet light in the presence of organic bromine or sulfur compounds was first accomplished and proved by Golub. The formation of trans units in natural rubber under similar conditions was not observed. The study of the isomerizing effect of TiCl4 and organo-aluminum compounds was conducted by us on solutions of milled natural rubber (NK) in benzene in sealed glass ampoules. The benzene used was dried and distilled over sodium. All work was conducted in an atmosphere of dry argon. Unsaturation and microstructure of the chain was determined on each sample. The study of microstructure of polyisoprenes was carried out by means of infrared spectra, the relative content of the different configurations of the polymer chain being determined by the absorption in the 800–1000 cm−1 region. The method previously developed by one of us was used for this purpose.

Synthesis and characterization of novel organosoluble aromatic copolyimides

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Jintian Yang ◽  
Wei Huang ◽  
Yongfeng Zhou ◽  
Deyue Yan ◽  
Xiaohang Wang
Keyword(s):  
Gel Permeation Chromatography ◽  
Polymer Chains ◽  
Polymerization Process ◽  
Synthesis And Characterization ◽  
Aprotic Solvents ◽  
Solution Casting ◽  
Molecular Weights ◽  
Gel Permeation ◽  
Dipolar Aprotic Solvents

AbstractA series of novel aromatic copolyimides was synthesized from pyromellitic dianhydride with the commercial diamine 4,4’-methylenebisaniline (MBA) and the diamine 4,4’-methylenebis(2-tert-butylaniline) (MBTBA) specially designed by ourselves. The solubility of the copolyimides in conventional solvents decreased with the mole ratio of MBTBA to MBA. When MBTBA/MBA was larger than 8/2, the copolyimides are soluble in low boiling point solvents (such as chloroform and tetrahydrofuran) and can form a transparent, flexible, tough film by solution casting. When MBTBA/MBA was between 7/3 and 5/5, the copolyimides are only soluble in dipolar aprotic solvents (such as dimethylformamide and N-methyl-2-pyrrolidone) and form films, too. The copolyimide was precipitated in m-cresol in the polymerization process when MBTBA/MBA was lower than 5/5. The number-average molecular weights of the soluble copolyimides measured by gel permeation chromatography were larger than 5.0·104 and the polydispersity index was higher than 1.5. Only one glass transition of these copolyimides was detected at around 350°C. The copolyimides did not show appreciable decomposition up to 400°C under air and 550°C under nitrogen, and their thermal stability increased a little with the introduction of MBA into the polymer chains.

scholarly journals Synthesis and Characterization of Copoly(Ether Sulfone)s with Different Percentages of Diphenolic Acid Units

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1817 ◽  
Author(s):  
Andrea A. Scamporrino ◽  
Concetto Puglisi ◽  
Angela Spina ◽  
Maurizio Montaudo ◽  
Daniela C. Zampino ◽  
...  
Keyword(s):  
13C Nmr ◽  
Microstructural Analysis ◽  
Molar Fraction ◽  
Polymer Chains ◽  
Molar Ratio ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Cyclic Oligomers ◽  
Ft Ir ◽  
Tof Ms

New functionalized Poly(ether sulfone)s having different molar ratio (10, 20, 30, 50, 70, 100 mol%) of 4,4-bis phenoxy pentanoic acid unit (diphenolic acid; DPA) units were synthesized and characterized by (1H and 13C)-NMR, MALDI-TOF MS, FT-IR, DSC and DMA analyses. The microstructural analysis of the copolymers, obtained by 13C-NMR using an appropriate statistical model, shows a random distribution of copolymer sequences, as expected. The presence of different amount of DPA units along the polymer chains affects the chemical and physical properties of the copolymers. The Tg and the contact angle values decrease as the molar fraction of DPA units increases, whereas the hydrophilicity increases. NMR and MALDI-TOF MS analyses show that all polymer chains are almost terminated with hydroxyl and chlorine as end groups. The presence of cyclic oligomers was also observed by MALDI-TOF MS analysis.

scholarly journals Catalytic Activity of Maghnite-H+ in the Synthesis of Polyphenylmethylsiloxane under Mild and Solvent-free Conditions

2017 ◽  
Vol 62 (2) ◽  
pp. 195 ◽  
Author(s):  
Djamal Eddine Kherroub ◽  
Mohammed Belbachir ◽  
Saad Lamouri ◽  
Larbi Bouhadjar ◽  
Karim Chikh
Keyword(s):  
Molecular Mass ◽  
Maximum Yield ◽  
Xrd Analysis ◽  
Operating Conditions ◽  
Polymer Chains ◽  
Average Molecular Mass ◽  
Solvent Free Conditions ◽  
Different Temperatures ◽  
Ir Analysis ◽  
Cationic Ring Opening Polymerization

In this study, a new and easy strategy was discussed for the purpose of synthesizing of a polymer of phenylmethylcyclosiloxane type (PPMS). The cationic ring opening polymerization of triphenyltrimethylcyclotrisiloxane (D3Ph,Me) was initiated by a solid, efficient and environmentally-friendly catalyst called Maghnite-H+. Maghnite-H+ is a natural clay composed essentially of montmorillonite, it is activated with an acid treatment by replacing the interlayer ions by protons, that results to the increase of the basal space, this may be confirmed by XRD analysis. The reaction was carried out without solvent at different temperatures and for different periods of time, using also several catalyst contents. Subsequently, the operating conditions were opted in order to obtain a maximum yield of the linear polymer and a high average molecular mass as well. The structure of polymers obtained was confirmed by IR analysis. 1H NMR and 13C NMR analyzes were used to follow the crosslinking of polymer chains over time. The thermal behavior was investigated by DSC analysis. The average molecular mass and the polydispersity indices were determined by GPC.

Preparation and X-Ray Crystal Structures of Tetrahydrofuran-Complexed Rare Earth Chlorides — a Structurally Rich Series

1998 ◽  
Vol 51 (1) ◽  
pp. 75 ◽  
Author(s):  
Glen B. Deacon ◽  
Tiecheng Feng ◽  
Peter C. Junk ◽  
Brian W. Skelton ◽  
Alexander N. Sobolev ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Crystal Structures ◽  
Ion Pairs ◽  
Far Infrared ◽  
Prolonged Treatment ◽  
Direct Reaction ◽  
Metal Powders ◽  
Metal Chlorides ◽  
X Ray ◽  
Linear Chains

Anhydrous lanthanoid metal chlorides LnCl3(thf)n (Ln = La, Ce, Nd, Sm, n = 2; Ln = Tb, Ho, n = 2·5; Ln = Dy, Tm, n= 2·7; Ln = Gd, Yb, Lu, n = 3; Ln = Er, n = 3·5) have been prepared in excellent yield by the direct reaction of the lanthanoid metal powders with hexachloroethane in tetrahydrofuran (thf), and (Ln = Eu, n = 0·8; Ln = La, n = 1·7; Ln = Pr, n = 2; Ln = Gd, n = 2·5; Ln = Er, n = 3) in good yield except for EuCl3(thf)0·8 from bulk metal. [YbCl3(thf)2]2 was prepared by prolonged treatment of solid YbCl3(thf)3 with pentane. The X-ray crystal structures of [LnC3(thf)2] (Ln = La, Ce or Pr), [LnCl3(thf)3.5] (Ln = Gd or Er), [YbCl3(thf)3] and [LaCl3(thf)(H2O)] have been determined. For [LaCl3(thf)2], a square antiprismatic single-stranded polymer, ... La(-Cl)3(thf)3La(-Cl)3(thf)2 ..., is the first eight-coordinate LnCl3(thf)n complex. The metal is surrounded by two sets of three bridging chlorines and cis thf oxygens. [LnCl3(thf)2] (Ln = Ce, Pr) have seven-coordinate structures with doubly chloride-bridged linear chains, ... LnCl(µ-Cl)3(thf)2LnCl(µ-Cl)2(thf)2 ... where the lanthanoid atom exists in a pentagonal bipyramidal environment, the pentagonal bipyramidal plane being defined by four chloride atoms and one oxygen atom of the thf ligand, and the axial positions being occupied by a chloride and a thf oxygen atom. [LnCl3(thf)3.5] (Ln = Gd, Er) crystallize as discrete ion pairs, [LnCl2(thf)5]+ [LnCl4(thf)2]¯. The lanthanoid atom in the cation displays pentagonal bipyramidal geometry with two apical chloride atoms and five equatorial thf ligands while the anion has quasi-regular octahedral stereochemistry with trans thf ligands. [LaCl3(thf)(H2O)] displays an eight-coordinate two-dimensional polymeric array with six bridging chlorides per lanthanum atom. Far-infrared spectra have been recorded for a number of products and used as a basis for structural proposals, particularly for products with fractional thf.

Sign in / Sign up

Export Citation Format

Share Document