Self-assembly of aniline oligomers in aqueous medium

Yu, Long; He, Wei; Feng, Jing; Jing, Xinli

doi:10.1007/s00396-012-2597-y

Cited by 18 publications

(15 citation statements)

References 50 publications

(78 reference statements)

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“…(a)] has a strong π–π* peak at 276 nm, a medium π–π* peak at 370 nm, and a weak p–π* absorption at 550 nm. As shown in Table , the locations of absorbance bands for the PANI synthesized under microwave irradiation were in close agreement with the previous studies . In previous studies, the acid‐free medium and low acidity concentration of polymerization systems were utilized to ensure some neutral aniline monomers to form branched oligomers and possible intermediate products, such as 1,2‐diphenylhydrazine, azobenzene, benzidine, and substituted quinone compounds.…”

Section: Resultssupporting

confidence: 87%

Exploration on the microwave‐assisted synthesis and formation mechanism of polyaniline nanostructures synthesized in different hydrochloric acid concentrations

Qiu

Wang

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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Under microwave‐assisted synthesis, polyaniline (PANI) products with multiple nanostructures were synthesized by the oxidative polymerization of aniline and ammonium peroxodisulfate in the different concentrations of hydrochloric acid solutions. The structural analysis of PANI using FTIR, UV, and XPS indicated that phenazine‐like oligomers were produced in acid‐free and low acidic systems. Moreover, long linear PANI chains were obtained in the presence of highly acidic solutions. The morphology of PANI observed by SEM and TEM showed that nanoscale structures, including stacked sheets, nanotubes, branched nanofibers, and uniform nanofibers, occurred respectively in acid‐free solution, low acidity, medium and high acidity systems, effectively regulating by acidity. The formation mechanism of PANI nanostructures was explored here. The sheets were formed by the oligomers containing flat phenazine rings that can be stacked together with strong π–π interactions. Furthermore, nanotubes were fabricated by the self‐curling of thin sheets consisted of phenazine‐like oligomers with numerous linear units in the chains. The nanofibers are supposed to form by the linear PANI chains and the secondary growth during aniline polymerization caused the branch formation on the nanofibers. All results indicate that acidity, rather than microwave assistance, is the critical factor that determines the polymerization mechanism and the final nanostructure. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3357–3369

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Section: Resultssupporting

confidence: 87%

Exploration on the microwave‐assisted synthesis and formation mechanism of polyaniline nanostructures synthesized in different hydrochloric acid concentrations

Qiu

Wang

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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“…The mass spectrum of the product (Fig. 17,25 Other peaks have to be assigned to more complex products. With a peak-topeak distance of m/z = 91 (the molecular mass of a repeat unit -C 6 H 4 -NH-), the peaks at 364, 455 and 546 m/z values should be due to aniline tetramers, pentamers and hexamers, respectively.…”

Section: Resultsmentioning

confidence: 99%

Ethanol-guided synthesis of (flower-on-leaf)-like aniline oligomers with excellent adsorption properties

Zhou

Gong

et al. 2015

New J. Chem.

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A novel oligoaniline with hierarchical flower-on-leaf microstructures has been fabricated via the oxidation of aniline in EtOH/water (3 : 7, v/v) mixtures. The as-prepared oligoaniline was characterized using the UV-vis, FTIR, 1 H NMR and MALDI-TOF MS techniques for analyzing the chemical structures.A possible formation mechanism has been proposed to interpret the growth of such hierarchical microstructures, and several inter-molecular interactions were suggested to drive the supermolecular assembly. The effect of the ethanol content in the medium on the morphology of the product was discussed, and the functions of the ethanol in the synthesis were explored. Besides, the adsorption properties of the as-prepared product toward organic dyes (crystal violet etc.) in water, as well as the sorption isotherms and kinetics, have been investigated carefully. The realizable sorption capacity for crystal violet was found to be 181 mg g À1 which was higher than those of most of the sorbent.

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“…As shown in Figure , the initial pH values of systems a and b were close, whereas pH in system a dropped quickly in the first 40 min and decreased to 1.68 at 240 min, as a much higher aniline concentration facilitated a faster polymerization rate and consequently rapid release of hydrogen ions. This quickly dropped pH may lead to the majority of products formed at a low pH level, so 1‐D products co‐existing with irregular nanoparticles became the main product . As a comparison, pH in system b decreased gently throughout the whole polymerization course.…”

Section: Resultsmentioning

confidence: 99%

“…As a comparison, in the spectrum of smooth microspheres, only a weak broad band around 466 nm and the free carrier tail is not obvious, reflecting the serious limitation of carriers’ delocalization. The absence of a peak around 800 nm may be due to presence of OQN, whereas both O and N could be suitable sites for hydrogen bonding …”

Section: Resultsmentioning

confidence: 99%

“…This quickly dropped pH may lead to the majority of products formed at a low pH level, so 1-D products co-existing with irregular nanoparticles became the main product. 9,21,22 As a comparison, pH in system b decreased gently throughout the whole polymerization course. It is probably that, on one hand, most of the early products in system b formed with pH > 3.2, where the less protonated aniline monomers will participate in ortho-coupling to form hydrophobic polymerization products, which are prone to organize into spherical particles to minimize their surface energy 8,9,11 ; on the other hand, a slowly proceeded polymerization may facilitate self-assembly of products with DTPA to shape PANI 15,23-25 into quasi-spherical structures based on the steric configuration of DTPA-aniline complex (Supporting Information, Scheme 1).…”

Section: Morphology Control With Different Ph Profilesmentioning

confidence: 93%

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Polyaniline self‐assembled with DTPA: Facilely tuned morphology and properties

Gibreel

Jing

et al. 2015

J of Applied Polymer Sci

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The effects of pH profile and “soft template” during aniline chemical oxidative polymerization (COP) were investigated and evaluated simultaneously with diethylene triamine pentaacetic acid (DTPA) as a structural directing agent. Formation of PANI nanotubes and nanoparticles, smooth microspheres, and urchin‐like microspheres were illustrated by evaluating the pH profile during aniline COP while considering the “soft template” effects of DTPA. PANI nanosheets with two semicurled edges were found in the system producing nanotubes, which provides an evidence for the “curling mechanism” of PANI nanotube formation. With different pH profiles, chemical structures and aggregation structures of the as‐synthesized PANI micro/nanostructures are similar, whereas their conductivity, wettability, Cr (VI) adsorption, and electrochemical behaviors are distinct. The present study indicates that if properly conducted, pH profile adjustment is more effective than “soft template” to control the morphology and to optimize the performance of PANI micro/nanostructures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42403.

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Self-assembly of aniline oligomers in aqueous medium

Cited by 18 publications

References 50 publications

Exploration on the microwave‐assisted synthesis and formation mechanism of polyaniline nanostructures synthesized in different hydrochloric acid concentrations

Exploration on the microwave‐assisted synthesis and formation mechanism of polyaniline nanostructures synthesized in different hydrochloric acid concentrations

Ethanol-guided synthesis of (flower-on-leaf)-like aniline oligomers with excellent adsorption properties

Polyaniline self‐assembled with DTPA: Facilely tuned morphology and properties

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