Unified Approach to Ion Transport and Structural Relaxation in Amorphous Polymers and Glasses

Abstract

Kinetic data for structural relaxation in silver iodomolybdates at the glass transition temperature (Tg) are obtained by high-pressure differential scanning calorimetry (HP-DSC) and are compared with activation energies (EA) and volumes (VA) obtained earlier from conductivities below Tg. The results are fitted to an empirical equation, EA = MVA, and displayed in the form of a master plot of EA versus VA, an approach previously applied to strongly coupled systems, including polymer electrolytes and molten salts above their glass transition temperatures. The parameter M emerges as a localized modulus, expressive of interatomic forces within the medium, linking together EA,sigma, VA,sigma and EA,s, VA,s, the "apparent" activation parameters for ionic conductivity and structural relaxation, respectively. The VA and EA values for ion transport are much smaller than the corresponding values for structural relaxation. However, remarkably close agreement emerges between the "process parameters", Ms and Msigma, both close to 8 GPa, thus establishing a quantitative link between ion transport and structural relaxation in this highly decoupled system. A new EA versus VA master plot is constructed, which points the way to a unified approach to ion transport in polymers and glasses.

Anomalous Electrical Conductivity Behavior at Elevated Pressure in the Protic Ionic Liquid Procainamide Hydrochloride

“…3 and 4, E act =ÁV # % 2 GPa above T g , increasing to about 4 GPa in glassy procainamide. These magnitudes and the increase for the glassy state are in accord with values reported for various organic and inorganic materials [23].…”

In search of invariants for viscous liquids in the density scaling regime: investigations of dynamic and thermodynamic moduli

“…Exploiting ambient and high pressure experimental data for selected supercooled van der Waals liquids as well as the criterion for the power density scaling law, we have verified the ideas on some material constants suggested by Ingram et al [18][19][20] preliminary attempt at taking up the challenge is simply to address to the first theoretical grounds for the power law density scaling, which suggest that the density scaling exponent is proportional to the exponent of the dominant repulsive part of the effective short-range intermolecular potential [10,43,44,45,46]. On the other hand, in consequence of our investigations, the density scaling exponent gains a robust interpretation as the material constant which indeed relates molecular dynamics and thermodynamics of viscous liquids, providing an additional argument for the concept of 'the thermodynamic scaling of molecular dynamics' as the density scaling is sometimes called.…”

“…(6), we analyze the ratios in isochronal conditions (i.e., at =const). Then, we can start from a known equation [19,20],…”

“…However, the proportionality between the dynamic and thermodynamic moduli, M p-T ~ B T , potentially providing a tempting linkage between molecular dynamics and thermodynamics of glass formers, were argued only phenomenologically by showing the same order of magnitudes of the moduli M p-T and B T in tested ionic systems by the authors [18][19][20].…”

First and Second Universalities: Expeditions Towards and Beyond

“…This includes friends and colleagues both inside and outside SFB 458, as well as KF's past coworkers. To name just a few, in alphabetical order, we would especially like to thank A. Bunde Besides thanking our friends at SFB 458 for an atmosphere of intense engagement and healthy exchange of views, we also would like to cite a few relevant results of theirs [110][111][112][113][114][115][116][117][118][119][120][121][122][123][124][125][126] which have added new insights while addressing issues complementary to those treated in this overview.…”