On the degradation of conducting Langmuir-Blodgett films

Carrara, Sandro; Gussoni, A.; Erokhin, Victor; Nicolini, Claudio

doi:10.1007/bf00188188

Cited by 7 publications

(7 citation statements)

References 21 publications

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“…It was also shown that the differentiation in fragment distributions with testing rate is evident at strain values much lower (Ϸ2.5%) than the strain typically required to complete the test (Ϸ4.2%). These results are consistent with the existence of stress concentrations at the end of broken fragments as described by Carrara and McGarry [10] and Jahankhani and Galiotis [11]. These stress concentrations can initiate failure of the fiber-matrix interface on the molecular level.…”

Section: Introductionsupporting

confidence: 90%

E‐glass/DGEBA/m‐PDA single fiber composites: Interface debonding during fiber fracture

et al. 2007

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In this paper, we examine the regions of debonding between the fibers and the matrix surrounding fiber breaks formed during single fiber fragmentation tests. The fiber breaks are accompanied by areas of debonding between the matrix and the surface of the fiber. With increasing applied strain, the lengths of these debonded regions generally increase. At the end of the test, the matrix tensile strain adjacent to the debond regions is an order of magnitude higher than the applied strain (40% vs. 4%). Although the debond edges typically remain attached at the same locations on the fiber fragments, debond propagation along fiber fragments under increasing strain has been observed in some cases. The phenomenon is termed secondary debond growth, and two mechanisms that trigger secondary debond region growth have been proposed. As expected, tests with bare fibers and with fibers coated to alter interface adhesion indicate that the average size of debonded regions at the end of the test increases as the calculated interfacial shear strength decreases. However, a decrease in the "apparent" interfacial shear strength resulting from an increase in testing rate results in a decrease in the size of the average debond region. This result suggests an increase in the amount of energy stored in the matrix from the fiber fracture process. POLYM. COMPOS., 28:561-574, 2007.

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Section: Introductionsupporting

confidence: 90%

E‐glass/DGEBA/m‐PDA single fiber composites: Interface debonding during fiber fracture

et al. 2007

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“…It can be explained by taking into account that the thickness of a single monolayer is nearly 24 ± 1 Å, while the height of the electrode is 40 nm. So, it is possible to have some breaking of the film at the electrode . When the potential is reversed, the hysteresis in the current−voltage can be observed.…”

Section: Resultsmentioning

confidence: 99%

Poly(o-anisidine) Langmuir−Schaefer Films: Fabrication and Characterization

et al. 1997

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The effect of pH on the Langmuir monolayer behavior was investigated for the poly(o-anisidine) (POAS) conducting polymer. The Langmuir−Schaefer (LS) films were prepared at pH 1 of the subphase, where the doping during the monolayer formation was essential for the high quality of the conducting polymer film. The LS films of POAS were characterized by using Fourier transform infrared spectroscopy, UV-vis absorption, X-ray diffraction, and ellipsometry techniques. The thickness of one monolayer of POAS film was estimated to 24 Å by using X-ray reflectivity and ellipsometric measurements. The uniformity of such POAS LS films was investigated for the redoping in 1 M HCl (protonic acid) for achieving the higher conductivity. The conductivity of the POAS LS film was shown to vary between 0.1 and 10-9 S/cm. Direct current through conducting LS films of POAS was observed as a function of monolayers. Further, the effects of different protonic acids on the electrical behavior of the POAS LS films were also investigated at length.

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“…Strong intermolecular interactions give rise to stable oligothiophene layers, which are essential for device fabrication. Under extreme electrical or thermal conditions, conductive oligothiophene film can degrade via progressive detachment of the adsorbates . While the threshold of thermal and electrical stability has been studied, the stability while exposed to various solvents has yet to be systematically investigated.…”

Section: Introductionmentioning

confidence: 99%

“…Under extreme electrical or thermal conditions, conductive oligothiophene film can degrade via progressive detachment of the adsorbates. 25 While the threshold of thermal and electrical stability has been studied, the stability while exposed to various solvents has yet to be systematically investigated. This work investigates the structure of oligothiophene LB films upon exposure to aqueous media, to evaluate the stability and determine if molecular level packing is interrupted.…”

Section: ■ Introductionmentioning

confidence: 99%

In Situ and Real-Time Atomic Force Microscopy Studies of the Stability of Oligothiophene Langmuir–Blodgett Monolayers in Liquid

et al. 2014

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Oligothiophene thin films have been considered as promising material for molecular electronics due to their desirable electronic properties and high structural stability under ambient conditions. To ensure performance in devices the functional structures, such as individual ordered domains, must be stable under practical and operational conditions or environments including exposure to various media. This work investigates the structure of oligothiophene Langmuir− Blodgett (LB) films upon exposure to liquid media such as water, ethanol (EtOH), and mixed tetrahydrofuran (THF)/EtOH solutions. The LB films form islands ranging from 500 nm up to 1 μm consisting of densely packed oligothiophene molecules. These islands are surrounded by bare substrate and loosely packed adsorbates. In situ and time-dependent AFM images were acquired to reveal the structural evolution, from which degradation pathways and kinetics are extracted. Degradation of these LB films initiates and propagates from intraisland defect sites, such as cracks and pin holes, whereas the edges of islands remain intact on the surface. The observations appear to be in contrast to the known degradation mechanism among self-assembled monolayers, such as alkanethiols on gold, which initiates and progresses at domain boundaries. Rationale for the observed degradation processes will also be discussed.

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On the degradation of conducting Langmuir-Blodgett films

Cited by 7 publications

References 21 publications

E‐glass/DGEBA/m‐PDA single fiber composites: Interface debonding during fiber fracture

E‐glass/DGEBA/m‐PDA single fiber composites: Interface debonding during fiber fracture

Poly(o-anisidine) Langmuir−Schaefer Films: Fabrication and Characterization

In Situ and Real-Time Atomic Force Microscopy Studies of the Stability of Oligothiophene Langmuir–Blodgett Monolayers in Liquid

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