Synthesis Of Aromatic Polymers Research Articles

High H-abstraction efficiency of Ni(II)-Ni(III)-Ni(II) cycle mediated oxidation of aromatic contaminants by peroxydisulfate

Peroxydisulfate (PDS) activation has attracted great attention for the treatment of aromatic contaminants in wastewater. In this study, the synthesized β-Ni(OH)2 exhibits remarkable reactivity in the catalytic oxidation of aromatic contaminants of phenol and aniline under alkaline conditions at a low molar ratio of 2:1 between the initial PDS and aromatic contaminants, indicating that the aromatic contaminants have not been completely mineralized into CO2 and H2O. By means of quenching experiments, LSV analysis and various characterizations, we rule out the primary contributions of •OH, SO4•−, O2•−, 1O2 or the non-radically activated PDS complexes to the oxidation processes. Instead, the oxidation cycle of Ni(II)-Ni(III)-Ni(II) plays the predominant role. DFT calculations further reveal the strong adsorption of phenol (-1.217 eV) and aniline (-1.166 eV) on β-NiOOH surface, which subsequently initiates H-abstraction from phenol and aniline by β-NiOOH with low interaction barriers of 0.119 eV and 0.467 eV, respectively. The produced aromatic radicals then undergo polymerization to produce phenol and aniline polymers. This work provides new insight on PDS activation and offers an effective and cost-saving approach for the removal, recycling, and synthesis of aromatic polymers.

Designing Thermally Stable Organocatalysts for Poly(ethylene terephthalate) Synthesis: Toward a One-Pot, Closed-Loop Chemical Recycling System for PET

Organocatalysis provides robust methodology to furnish “greener” routes to polymer synthesis. However, the application toward the synthesis of aromatic polymers via step-growth polymerization is an area that justifies more investigation, as a consequence of the poor thermal stability of many organic catalysts and the high reaction temperatures commonly required. In this study, thermally stable organic salts consisting of an organic base and an organic acid were explored to understand key elements required for the bulk synthesis of poly(ethylene terephthalate) (PET) at 270 °C. The ΔpKa values of the salts played an important role in the thermal stability such that the salts with higher ΔpKa values showed higher stability because of the strong acid–base interactions. The 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) salts with high ΔpKa values (≥16.9) showed the best catalytic activity among the investigated salts in terms of both low amounts of side reactions and discoloration. The thermal and chemical stability of the salts also affected the polymer properties. Dimerization side reactions that lead to defects in the polymer backbone were found to occur more readily in salts containing strong acids as components, particularly as the ΔpKa between the acid–base components decreased. The discoloration of the PET sample was also correlated to the thermal stability of the organic salt catalyst, with a lower stability generally leading to enhanced discoloration likely due to decomposition of base components. Polymerization–depolymerization cycles were also investigated with the TBD:p-toluenesulfonic acid (TSA) salt and the feasibility of simple, closed-loop recycling of PET with the system was established.

Composite Membrane of Zirconium Sulfate -Poly(Ether Sulfone Quinoxalines) for Hydrogen and Direct Methanol Fuel Cells

The synthesis of aromatic polymers containing quinoxalines and preparation of composite proton exchange membranes with zirconium sulfate is described. Poly(ether sulfone quinoxalines) was synthesized via condensation polymerization from dihydroxyquinoxaline, bis(4-fluorophenyl)sulfone, and bisphenol monomers in N-methylpyrrolidone at 175-180oC. The synthesized polymer has a molecular weight of ~32,000 Daltons and glass transition temperature of ~176±2oC. The polymers were sulfonated using chlorosulfonic acid in concentrated sulfuric acid. The composite membranes were prepared from zirconium sulfate and blend of sulfonated poly(ether sulfone quinoxalines) and sulfonated polyethersulfone. Membrane electrode assemblies containing 25cm2 of active area were prepared with a catalyst loading of 3mg/cm2. The performance of the MEAs was characterized using a single fuel cell tester with hydrogen and methanol as the fuel sources. The methanol concentration was investigated from 3 v/v% to 20 v/v%. The peak power of the fuel cell was 108 mW for 20 v/v% methanol and a power of 750mW fueled with hydrogen at 5psi backpressure.

ChemInform Abstract: Synthesis of Aromatic Polymers from Nitro-Substituted Monomers

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Condensation Monomers and Polymers Based on 2,4,6‐Trinitrotoluene

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of aromatic polymers via palladium‐catalyzed cross‐coupling reactions with magnesium, zinc, and tin reagents: A comparison

AbstractDifunctional magnesium, zinc, and tin reagents MC6H4OC6H4M (M = MgBr, ZnCl, SnBu3) in the presence of palladium or nickel catalysts undergo cross‐coupling polymerizations with aromatic, heteroaromatic, benzylic, and allylic dihalides to give oligomeric and polymeric materials. Tin reagents lead to products of higher molecular weight than Mg and Zn reagents. The reaction is sensitive to the solvent and enhanced by magnesium halides. Increased reaction temperatures lead only to moderate increases in the degree of polymerization and are limited by catalyst decomposition above 200°C. The new poly(ether ketone) and poly(ether sulfone) type polymers prepared show high thermal stability. In contrast to conventional poly(ether sulfones)s, the biphenyl‐based sulfone polymers reported here are crystalline. © 1992 John Wiley & Sons, Inc.

Synthesis of aromatic polymers by the reaction between monomers containing biphenylene and acetylene groups

The thermal reaction of a bis(biphenylene) monomer, N,N′-bis(biphenylene-2-yl)-4,4′-hexafluoroisopropylidenediphthalimide (3), with either of two diacetylenic monomers, bis(4-ethynylphenyl) ether (4) or bis[4-(phenylethynyl)phenyl] ether (5), gave polymers that contain phenanthrene units as a result of the reaction of the biphenylene groups with the acetylene groups. The reaction could be carried out in solution or in the melt, and in the latter case, reaction exotherms were found at 367°C and 386°C, respectively, for 4 and 5. Polymer 6, obtained from the melt reaction of 3 with 5, is insoluble in all solvents and thermally stable, showing no weight loss in air up to 480°C and in argon up to 500°C.

新しい重縮合による芳香族系高分子の合成

新しい重縮合による芳香族系高分子の合成

Synthesis of aromatic polymers containing anthrazoline and isoanthrazoline units

AbstractThe condensation of bisketomethylene monomers with either 4,6‐dibenzoyl‐1,3‐phenylenediamine or 2,5‐dibenzoyl‐1,4‐phenylenediamine catalyzed by acid affords high molecular weight polymers containing the anthrazoline and isoanthrazoline units in the polymer main chain. Base is not an effective catalyst for the production of high molecular weight polymer. The phenyl substitution on the anthrazoline and isoanthrazoline units increases the solubility of these polymers over those in which phenyl substitution is absent. The rodlike character of these polymers, which can be altered by positional isomerism in the chain, has an effect on the solution properties.