Time-Humidity-Superposition Principle in Electrical Conductivity Spectra of Ion-Conducting Polymers

Water-Triggered Conduction Mediated by Proton Exchange in a Hygroscopic Fulleride and Its Hydrate

“…In the same temperature range of the conductivity change, the loss feature undergoes a non-monotonous frequency shift and a significant decrease in strength (by a factor of three). The observed decrease of σ dc upon desorption of water is reminiscent of the behavior of many insulating and semiconducting porous inorganic materials [2][3][4][5] in which a conductivity enhancement is observed after exposure to humidity. It may be gathered from panel c that the conductivity variation is approximately of four orders of magnitude, a dramatic effect which is in line with reported conductivity enhancements in inorganic systems.…”

“…This suggests that only the hydrated forms of the derivatives C 60 (OX) 24 (X = H, Na), and not the pure materials, behave as proton conductors. Moreover, our findings help shed light on two well-known and yet controversial water-induced conductivity effects, namely the surface conductivity enhancement and the worsening of electrical insulation in a humid environment, [2][3][4][5][6] and the conductivity changes associated with structural dehydration. …”

“…1 Exposure to humid air and the ensuing condensation of water vapor onto a material's surface introduces new mechanisms for charge generation and transport, which in semiconducting and insulating materials may result in an increase of the overall conductivity by several orders of magnitude. [2][3][4][5][6] This well-known effect is exploited in many kinds of humidity sensors based on inorganic materials such as ceramics or organic materials such as polymers. 7,8 The presence of water can also have an important effect on the dielectric response of materials, e.g.…”

“…9 The dc conductivity of organic and inhomogeneous inorganic semiconductors in their pure form is quite low, so that the introduction of new charge carriers or conduction paths upon adsorption of water leads in many instances to an increase in the material's conductivity, for some cases even by several orders of magnitude. [2][3][4][5][6] The exact mechanism underlying such effect both in organic and inorganic systems is a matter of debate, 2 and it may not be unique nor the same for all materials.…”

Deviation from time-composition equivalence in polymer solutions with selective cosolvents

“…Examples of systems exhibiting tCS include plasticized homopolymers, 2 surfactant solutions, 3 interfacial monolayers, 4 ionomer-salt solutions, 5 and ion-conducting polymers. 6 We have recently reported 7 that tCS occurs in thermoplastic elastomeric triblock copolymer solutions containing two midblock-selective cosolvents that are miscible with each other but that differ considerably in terms of chemical constitution and viscosity (which can be related to various system characteristics). 8,9 Under thermodynamically favorable conditions, block copolymers can spontaneously self-assemble into a wealth of nanostructures that reflect competitive enthalpic and entropic contributions to the system free energy.…”