A solid state NMR characterization of cross-linked polyaniline powder

Mathew, Roy J.; Mattes, Benjamin R.; Espe, Matthew P.

doi:10.1016/s0379-6779(02)00177-7

Cited by 80 publications

(72 citation statements)

References 31 publications

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“…19 The ACAT was similar to EB PANI in thermal crosslinking behavior, as shown by the differential scanning calorimetry (DSC) thermogram (Fig. 4), in which the endothermic peak at 81°C was attributed to the melting of the crystalline powder and the exothermic peak at 187°C was attributed to the quinoid crosslinking reactions (enthalpy ϭ 43.7 kJ/mol).…”

Section: Acat/epoxy Resin Intercrosslinked Networkmentioning

confidence: 62%

Amino‐capped aniline trimer/epoxy resin intercrosslinked networks

Yang

Jiang

Zhao

et al. 2006

J of Applied Polymer Sci

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An amino-capped aniline trimer (ACAT) in emeraldine base form was reacted with an epoxy resin to produce intercrosslinked networks. The quinoid structure of the ACAT was able to crosslink on curing and, thus, led to a very high glass-transition temperature of the cured resin. The epoxy resin cured with the ACAT showed superior thermal properties over the resins cured with p-phenylenediamine and 4,4Ј-diamino diphenylamine. These findings were based on differential scanning calorimetry, IR, dynamic mechanical analysis, and thermogravimetric analysis data.

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Section: Acat/epoxy Resin Intercrosslinked Networkmentioning

confidence: 62%

Amino‐capped aniline trimer/epoxy resin intercrosslinked networks

Yang

Jiang

Zhao

et al. 2006

J of Applied Polymer Sci

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“…Conducting polymers such as PANI and polypyrrole are being considered for a range of applications [2]. Asa powerful analytical toot, solid-state NMR, especially CP MAS and related techniques have been used to study PANI [3][4][5][6][7][8][9][10][11][12][13][14]. These techniques can sensitively reflect mutual interactions of the spins and their interactions with the external magnetic field, which makes them useful in structural investigations of insoluble solid materials such as PANI and other conducting polymers in their as synthesized form.…”

Section: Introductionmentioning

confidence: 99%

Solid-state magnetic resonance studies of polyaniline as a radical scavenger

et al. 2005

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The first detailed study of polyaniline (PANI) and reduced PANI (R-PANI) before and after reaction with the stable organic free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) by using solidstate 13C CP MAS (cross-polarization magic-angle spinning), NQS (nonquaternary suppressed) and CPPI (cross-polarization phase inversion) nuclear magnetic resonance teehniques is reported. These techniques reveal relatively subtle structural changes that occur upon reaction with DPPH free radicals and confirm the radical scavenging ability of PANI. The integrated intensity of the PANI CP MAS spectrum after reaction with DPPH is about 8% larger than that of PANI and this cannot be explained by an oxidation process alone. The increase is attributed to a decrease in the polaron concentration in the polymer, which is consistent with electron paramagnetic resonance (EPR) data that show a decrease of the EPR signal intensity after reaction of chemically synthesized PANI with DPPH.

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“…[25,27] Cross-linking in flash welded polyaniline nanofiber films is not surprising since temperature induced cross-linking has been reported previously. [28][29][30] The chemo-mechanical actuation induced by immersion of the dedoped polyaniline asymmetric membrane in 0.5 M camphorsulfonic acid nears completion with an approximately 720°rotation from its original position in 20 s (Fig. 3, top left).…”

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confidence: 99%

Monolithic Actuators from Flash‐Welded Polyaniline Nanofibers

et al. 2007

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Asymmetric films formed by flash-welding polyaniline nanofiber mats demonstrate rapid reversible actuation in the presence of select aqueous acids and bases. These continuous single component bending/curling actuators have several advantages over conventional dual component, bimorph actuators including ease of synthesis, large degree of bending, patternability and no delamination. The films are made through a controlled, facile, all aqueous process that yields water dispersed polyaniline nanofibers that are readily cast into films. Flash welding photothermally cross-links and melts the top surface of the nanostructured polymer producing an asymmetric film. The resultant cross-linked surface is quite dense and has a reduced number of protonic acid doping sites available. The film surface is therefore less susceptible to the protonic acid doping which expands the underlying high surface area nanofiber layer. Actuation occurs at a comparable or faster rate than bimorph actuators with an unprecedented > 720°bending relative to the initial flat position for a 2.5 cm length film. The collective movement of the individual nanofibers in the asymmetric film creates a large degree of actuation resembling natural muscle. These bending actuators could be developed for use in microtweezers, microvalves, artificial muscles, chemical sensors and/or patterned actuator structures.Polyaniline and other conducting polymers have been of interest for their actuation properties for more than two decades. [1][2][3][4][5][6][7][8] The actuation is due to the unique chemistry of conducting polymers, which generally swell reversibly with the incorporation of dopant ions and their associated solvent molecules. Previous work on polyaniline actuators has involved dispersing conventional polyaniline in highly polar solvents such as N-methyl pyrrolidinone for casting into fibers, [9][10][11] rods, [12][13][14] sheets, [5] layered bimorphs [15,16] and integrally skinned asymmetric membranes. [7,[17][18][19] Elongation or contraction of polyaniline films and fibers has been induced by oxidation state, electrostatic or conformational changes as well as combinations of all of these to create linear or bending movement depending on the initial structure. Typical bending actuators require the use of two or more different materials bound together to produce a bimorph. One material forms the active part that expands or contracts relative to the inactive part upon stimulation, thus inducing bending. Bending of bimorph structures has generally been limited to < 90°and problems with adhesion between the layers often leads to delamination especially with extended use. [20] Alternative bending structures have been proposed such as active dual layers, which expand and contract cooperatively.[21] Wang, et al. [7] made a major advance by developing integrally skinned asymmetric membrane (ISAM) bending polyaniline actuators. ISAMs use a single material processed so that one side of the film has much higher porosity than the other side. Doping induced swelling ...

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A solid state NMR characterization of cross-linked polyaniline powder

Cited by 80 publications

References 31 publications

Amino‐capped aniline trimer/epoxy resin intercrosslinked networks

Amino‐capped aniline trimer/epoxy resin intercrosslinked networks

Solid-state magnetic resonance studies of polyaniline as a radical scavenger

Monolithic Actuators from Flash‐Welded Polyaniline Nanofibers

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