Soft matter under Confinement

By means of dielectric spectroscopy (DS) and complementary techniques we are studying the thermodynamics and dynamics of soft materials under confinement. Confinement here is provided by nanoporous hard templates that provide a two-dimensionally confined space in which self-organization processes such as crystallization, protein secondary structure formation, mesophase formation and phase separation can be altered (Figure 1). Understanding the self-assembly, thermodynamics and dynamics of soft materials under confinement will allow for their rational design as functional devices with tunable mechanical strength, processability, electronic and optical properties.

In recent years there have been concerted efforts in both theory and experiment to understand the way that polymers penetrate nanopores. An advancement in studying polymer imbibition has been the, so-called, nanofluidic method based on DS (i.e. nano DS). The method provides quantitative information on the imbibition process. In addition, it provides access to length and time scales (from the local segmental, to internal chain modes, to the longest normal mode and to the much slower adsorption process) under non-equilibrium conditions (e.g. during flow) not considered before. In polymers results provide unambiguous evidence for growing interfacial interactions.

In a second area, we investigate how confinement affects the crystallization and dynamics of hydrogen bonded systems, including water. By studying model confining systems, we provide new insights into the properties of confined water/alcohols with possible applications in cryopreservation.

Imbibition — Figure 2. (left) Schematic of the chemical structure of the ILs in cylindrically (C)- and V-shaped confinement (AAO). (right) Comparison of temperature dependence of dc-conductivity for bulk (gray) and confined [BMIM]+[BF4]- in V-shaped (blue) and cylindrically shaped AAO (red) following imbibition.

Figure 2. (left) Schematic of the chemical structure of the ILs in cylindrically (C)- and V-shaped confinement (AAO). (right) Comparison of temperature dependence of dc-conductivity for bulk (gray) and confined [BMIM]+[BF4]- in V-shaped (blue) and cylindrically shaped AAO (red) following imbibition.

In a third area we investigate ion transport in nanochannels (Figure 2). We address how confinement geometry, molecular architecture (ionic liquids and polymerized ionic liquids), and dynamic electrostatic forces collectively govern ion transport and fluid flow, with importance in the design of materials for energy storage, nanofluidics, and sensing technologies.

References:

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