Dynamics of Pyrrolidinium-Based Ionic Liquids under Confinement. II. The Effects of Pore Size, Inner Surface, and Cationic Alkyl Chain Length

Geometric nanoconfinement, in one and two dimensions, has a fundamental influence on the segmental dynamics of polymer glass-formers and can be markedly different from that observed in the bulk state. In this work, with the use of dielectric spectroscopy, we have investigated the glass transition behavior of poly(2-vinylpyridine) (P2VP) confined within alumina nanopores and prepared as a thin film supported on a silicon substrate. P2VP is known to exhibit strong, attractive interactions with confining surfaces due to the ability to form hydrogen bonds. Obtained results show no changes in the temperature evolution of the α-relaxation time in nanopores down to 20 nm size and 24 nm thin film. There is also no evidence of an out-of-equilibrium behavior observed for other glass-forming systems confined at the nanoscale. Nevertheless, in both cases, the confinement effect is seen as a substantial broadening of the α-relaxation time distribution. We discussed the results in terms of the importance of the interfacial energy between the polymer and various substrates, the sensitivity of the glass-transition temperature to density fluctuations, and the density scaling concept.

show abstract

“…Apart from that, such correction is also obligatory when evaluating the dielectric properties of nanopore-confined ionic liquids. 72 , 73 …”

Section: Methodsmentioning

confidence: 99%

On the Segmental Dynamics and the Glass Transition Behavior of Poly(2-vinylpyridine) in One- and Two-Dimensional Nanometric Confinement

Winkler

Unni

et al. 2021

J. Phys. Chem. B

Self Cite

View full text Add to dashboard Cite

show abstract

“…The IL 1-hexyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([C 6 MPyrr] + [Tf 2 N] − , M w = 450.47 g/mol) with 99.9% purity was purchased from Solvionic SA (France). The calorimetric glass transition temperature of this IL is T g = 189 K . Confinement is realized using self-ordered AAO membranes provided by SmartMembranes GmbH (Germany), which feature straight and noncross-linked channels opening to both sides of the membrane with a porosity (total channel volume fraction) of φ = 0.47.…”

Section: Methodsmentioning

confidence: 99%

“…The temperature was controlled by a Novocontrol Quatro nitrogen gas cryostat, which ensures temperature stability within ±0.1 K. Alumina membranes filled with the IL were placed between the two round electrodes matching the size of the membranes. For experimental details, see Part II …”

Section: Methodsmentioning

confidence: 99%

Dynamics of Pyrrolidinium-Based Ionic Liquids under Confinement. I. Analysis of Dielectric Permittivity

Richert

Adrjanowicz

2020

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

Dielectric spectroscopy of geometrically confined ionic liquids is an effective approach to study how finite size and interfacial effects modify the conductivity behavior. An ideal geometry for such experiments are pores or channels that run parallel to the electric field lines, as in this case, no Maxwell–Wagner-type effect is assumed to interfere with a straightforward data analysis. However, the permittivity of such channels in anodized alumina membranes filled with the ionic liquid shows the hallmark of significant Maxwell–Wagner-type polarization. This work provides a simple model that explains this lack of low-frequency conductivity, assuming air pockets to be located between the liquid and the electrode. A correction of the observed data according to this model provides an improved definition of the dc-conductivity levels.

show abstract

“…Confinement is a good strategy to modify the polymer and ion dynamics in PILs, and numerous works have studied the confinement on small-molecule ILs, − which revealed the importance of surface interactions and provided insight into PIL confinement. Common methodologies include the uses of nanostructured block copolymers, nanoporous templates, or nanothin films .…”

Section: Introductionmentioning

confidence: 99%

Ion Specific, Thin Film Confinement Effects on Conductivity in Polymerized Ionic Liquids

et al. 2021

View full text Add to dashboard Cite

Acrylate-based polymerized ionic liquids (PILs) with ammonium (Am) or imidazolium (Im) cations and tetrafluoroborate (BF 4 ) or bis(trifluoromethanesulfonyl)imide (TFSI) anions were synthesized and spin coated onto gold interdigitated electrodes on silica to investigate nanoconfinement effects on ion transport. The film thickness ranged from 23 to 313 nm. A significant reduction of the inplane conductivity was observed in some PIL thin films with thickness below 100 nm. Specifically, Am BF 4 PIL showed the largest conductivity drop (ca. 50% difference between a 22 nm and a 261 nm film) while Im TFSI PIL showed almost no change under confinement. The difference in conductivity drop is discussed in terms of (i) differences in interfacial layer thickness by fitting a two-layer conductivity model and (ii) potential changes in glass transition temperature (T g ) under confinement, which were estimated using the Vogel−Fulcher−Tammann fits of bulk conductivities. Decreasing film thickness also caused the dielectric loss peaks to shift to lower frequency, indicating that the ion diffusion process slowed under confinement.

show abstract

Dynamics of Pyrrolidinium-Based Ionic Liquids under Confinement. II. The Effects of Pore Size, Inner Surface, and Cationic Alkyl Chain Length

Cited by 25 publications

References 70 publications

On the Segmental Dynamics and the Glass Transition Behavior of Poly(2-vinylpyridine) in One- and Two-Dimensional Nanometric Confinement

On the Segmental Dynamics and the Glass Transition Behavior of Poly(2-vinylpyridine) in One- and Two-Dimensional Nanometric Confinement

Dynamics of Pyrrolidinium-Based Ionic Liquids under Confinement. I. Analysis of Dielectric Permittivity

Ion Specific, Thin Film Confinement Effects on Conductivity in Polymerized Ionic Liquids

Contact Info

Product

Resources

About