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Item type:Publication, Access status: with files , Water in mesoporous materials: investigating capillary flow, elastocapillarity, and phase transitions with molecular dynamics simulations(2026); Water-driven mesoporous materials offer great potential for sustainable applications. This work elucidates the analytical modeling of capillary flows of water in ordered, cylindrical silica mesopores and the resulting imbibition-induced elastocapillarity. The results could support the development of novel sensors, and actuators. In addition, a method for enabling liquid-to-solid phase transitions in molecular dynamics simulations is presented. In the future this method could be used to investigate liquid-to-solid phase transitions in mesoporous materials.Publicationtype: Doctoral Thesis42 49 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , An optical study of nanofluidics in mesoporous silicon(2025); This thesis presents a novel method for studying capillary imbibition and vapor sorption in mesoporous silicon (PSi) with white light spectroscopy. By Fast-Fourier-Transformation of thin film interference and parallel analysis of an optical microcavity within the porous layer, it achieves high precision in monitoring fluid dynamics. The research includes a constriction model for capillary imbibition, the resolution of liquid menisci and a percolation mechanism for vapor sorption. Moreover, a new rapid and non-destructive technique is introduced for assessing pore pathways of PSi, by calulating the pore geometry from liquid dynamics and capillary pressure.Publicationtype: Doctoral Thesis75 53 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Electrochemical actuation of porous silicon in aqueous electrolytesPorous silicon is highly versatile functional material. In this thesis two different electrochemistry-inspired approaches are developed and investigated to integrate an actuator functionality into porous silicon. The first approach aims to utilise electrochemo-mechanical coupling at the interface of a porous silicon electrode immersed in an aqueous electrolyte solution. The second approach comprises the integration of the electroactive, electrically conductive polymer polypyrrole into the porous silicon pore structure to create a hybrid material. Both approaches achieve a robust and highly reproducible actuation that follows the applied potential linear and whose work density compares well to classical piezo actuators.Publicationtype: Doctoral Thesis196 2895 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Self-assembly of confined liquid crystals: from nanoscale physics to designing photonic metamaterials(2020); Liquid crystals in combination with nanoporous media, exhibiting structures significantly smaller than the wavelengths of visible light, are promising candidates to design new soft-hard photonic metamaterials. The liquid crystal provides functionality, resulting from temperature tunable anisotropic properties, i.\,e. optical birefringence, while the nanoporous solid provides a mechanical robust scaffold structure. Then the optical functionality of prospective metamaterials is not determined by the properties of base materials, but from newly designed multiscale structures often absent in the base materials. However, the extreme spatial and topological constraints can result in inhomogeneous molecular arrangements or even the complete suppression of liquid crystallinity in nanoconfinement hampering the optical functionality. Depending on the type of confining space (meso- and macroporous silica and anodized aluminium oxide) and as a function of temperature, pore size and pore surface chemistry, the molecular self-assembling process and the resulting metamaterial potential of a discotic liquid crystal (HAT6) in nanoconfinement is analyzed. In order to correlate orientational and translational ordering, synchrotron-based 2D X-ray diffraction in combination with high-resolution optical polarimetry measurements are performed. Resulting from a quantized phase transition a rarely measured material specific parameter giving a measure of the tendency of the liquid crystal to bend along the preferred alignment direction is found. Additionally, the experiments and complementary Monte Carlo simulations show a remarkably rich self-assembly behavior resulting in structures absent in the bulk state. These diverse configurations on the nanoscale result in integrated material systems exhibiting a temperature- and liquid-solid interaction-dependent positive and negative optical birefringence. Hence, the self-organized nanoporous solids in combination with liquid-crystalline self-assembly allow the fabrication of newly designed photonic metamaterials with tailorable optical anisotropy.Publicationtype: Doctoral Thesis461 494 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Soft condensates in hard confinement : structure and molecular mobility(2019-12-20); The properties of soft matter in the nanoscopic constriction within the voids of surrounding hard condensed matter are investigated. The document is divided into two parts: The first one is concerned with the temperature- and pores-size-dependent analysis of the molecular dynamics of a room-temperature ionic liquid within the nanopores of porous carbons, employing quasi-elastic neutron scattering techniques. In the second part, the structure of different chiral liquid crystals embedded within anodic aluminium oxide nanochannels is investigated as a function of temperature and pore width.Publicationtype: Doctoral Thesis505 1603