Using in situ nanodielectric spectroscopy we demonstrate that the imbibition kinetics of cis-1,4polyisoprene in native alumina nanopores proceeds in two time regimes both with higher effective viscosity than bulk. This finding is discussed by a microscopic picture that considers the competition from an increasing number of chains entering the pores and a decreasing number of fluctuating chain ends. The latter is a direct manifestation of increasing adsorption sites during flow. At the same time, the longest normal mode is somewhat longer than in bulk. This could reflect an increasing density of topological constraints of chains entering the pores with the longer loops formed by other chains.

It is often assumed that carbon nanotubes (CNTs) stimulate neuronal differentiation by transferring electrical signals and enhancing neuronal excitability. Given this, CNT–hydrogel composites are regarded as potential materials able to combine high electrical conductivity with biocompatibility, and therefore promote nerve regeneration. However, whether CNT–hydrogel composites actually influence neuronal differentiation and maturation, and how they do so remain elusive. In this study, CNT–hydrogel composites are prepared by in situ polymerization of poly(ethylene glycol) around a preformed CNT meshwork. It is demonstrated that the composites facilitate long‐term survival and differentiation of pheochromocytoma 12 cells. Adult neural stem cells cultured on the composites show an increased neuron‐to‐astrocyte ratio and higher synaptic connectivity. Moreover, primary hippocampal neurons cultured on composites maintain morphological synaptic features as well as their neuronal network activity evaluated by spontaneous calcium oscillations, which are comparable to neurons cultured under control conditions. These results indicate that the composites are promising materials that could indeed facilitate neuronal differentiation while maintaining neuronal homeostasis.

Using in situ nanodielectric spectroscopy, we studied the adsorption kinetics of cis-1,4-polyisoprene (PI) into porous alumina by following the evolution of the dielectrically active longest normal mode. We studied the influence of molar mass, nanopore diameter, and surface functionalization. Adsorption times depend strongly on the ratio 2R g/D, where R g is the radius is gyration and D is the pore diameter. For a given pore diameter, the characteristic adsorption times are some 8 orders of magnitude slower than the terminal relaxation times and more than 12 orders of magnitude slower than the segmental times. The extremely slow kinetics reflect the fact that exchanging chains with the pore surface have to pass through several unfavorable configurations (e.g., trains, loops). The molar mass dependence of the characteristic adsorption times (τads ∼ N 2.6) is in good agreement with a scaling theory proposed by de Gennes and later refined by Semenov and Joanny. Subsequently, we investigated the imbibition of miscible PI blends by taking advantage of the difference in imbibition speeds of the respective homopolymers. We show that the shorter chains penetrate first the nanopores, whereas the longer chains enter only at the late stages of the filling process. Moreover, the long-time adsorption is dominated by an exchange mechanism involving primarily the shorter chains. The results from in situ nanodielectric spectroscopy demonstrate the capacity of the technique to provide the imbibition length, the adsorption kinetics, and, at the same time, the chain dynamics.

Using in situ nanodielectric spectroscopy, we investigate if and how the ionic conductivity of the archetypal polymer electrolyte poly(ethylene oxide)/lithium bis-(trifluoromethane sulfone)imide (PEO/LiTFSI) is affected during and after imbibition in nanopores. We identify two distinct stages of imbibition. In the first stage, up to the complete pore filling, ion conductivity increased above the bulk value. In the second stage, after imbibition, ion conductivity decreased following a stretched exponential dependence. Time-of-flight secondary ion mass spectroscopy revealed a uniform distribution of Li + and TFSI − ions in the templates. The timescale of conductivity reduction was very long. For a given molar mass, the characteristic times strongly depend on the ratio 2R g /D where R g is the radius of gyration and D is the pore diameter. For a given pore diameter, the characteristic times were some 9 orders of magnitude slower than the PEO terminal relaxation and more than 11 orders of magnitude slower than the segmental relaxation. The reduced ionic conductivity is explained by the adsorption of polymer segments on the pore walls. Polymer adsorption inevitably affects ion dynamics by (i) increasing the glass temperature and (ii) reducing the number of mobile ions. The molar mass dependence of the characteristic adsorption times (τ ads ≈ N 2 ) was in agreement with a scaling theory proposed by de Gennes. Possible consequences of the current study to energy conversion are discussed.

The imbibition dynamics of poly­(n-butyl methacrylate) (PnBMA) in nanoporous alumina is studied by in situ dielectric spectroscopy at temperatures in the range 30–50 K above the glass temperature. A model provides the imbibition length from the measured dielectric strength of the segmental process. The relaxation times of the segmental process during imbibition are isochronal, except at early stages where a speed-up is observed. Furthermore, as polymer segments flow inside the pores, the distribution of relaxation times remains constant (Havriliak–Negami shape parameters similar to the bulk). Imbibition at longer length scales associates with the effective viscosity of the chains and provides a stringent test of the Lucas–Washburn equation applicable to Newtonian liquids. The equation fails to describe the imbibition process because the prefactor to the t 1/2 (t; time) dependence does not adequately describe the process. Imbibition of polymer blends composed of long and short chains reveals the enrichment of the pores by the shorter chains by their faster imbibition with possible application in fractionation.