arXiv subjects

Viktor Mandrolko

Publications and source records attributed to Viktor Mandrolko.

5 recordsLinked to original sources

arXiv2025

Tailored Thermal Transport in Phase Change Materials-Based Nanocomposites through Interfacial Structuring

Interfacial thermal transport is a critical bottleneck in nanoscale systems, where heat dissipation and energy efficiency are strongly modulated by molecular ordering at solid-liquid boundaries. Here, using atomistic simulations of hexadecane confined by structured silica substrates, we reveal how interfacial geometry, specifically curvature, governs the density distribution and thermal transport across the interface. On flat and mildly curved surfaces, the liquid exhibits surface-templated layering, promoting efficient heat transfer, which is enhanced as the contact surface area increases. As curvature increases, this ordering breaks down, giving rise to interference-like density patterns, reduced molecular packing, and localized depletion zones. This structural reorganization leads to a systematic increase of up to 10 % in interfacial thermal resistance (ITR), even when the contact area is kept constant. By decomposing the interface into convex ("hills" of the solid) and concave ("valleys" of the solid) regions, we find that valleys consistently exhibit lower ITR. In contrast, hills act as bottlenecks to heat flow, leading to interfacial thermal resistance values up to 70% higher than those of valleys, depending on the surface configuration. Remarkably, we show that the work of adhesion and entropy-related energy gain upon liquid detachment scale non-trivially with curvature: while adhesion increases with contact area from 30 mJ*m^(-2) for a flat surface to 40 mJ*m^(-2) for a maximum curvaceous surface, the entropic penalty dominates the total energy change, reflecting curvature-induced frustration of molecular alignment.

cond-mat.mes-hall↗

arXiv2025

Tailoring Heat Transfer at Silica-Water Interfaces via Hydroxyl and Methyl Surface Groups

Efficient thermal transport across solid-liquid interfaces is essential for optimizing heat dissipation in modern technological applications. This study employs molecular dynamics (MD) simulations to investigate the impact of surface functionalization on heat transfer at the silica/water interface. It has been shown that the surface functionalization changes significantly the wetting characteristics of silica surface: from one hand hydroxyl groups render such surfaces more hydrophilic, while methyl groups more hydrophobic. Here, we reveal that modifying the surface functionalization from methylated to hydroxylated groups results in: (i) up to an approximately eightfold increase in adhesion energy, (ii) a reorientation of interfacial water molecules to align perpendicular to the surface normal, (iii) a reduction in the liquid depletion length near the interface, and (iv) an overall enhancement of interfacial heat conduction. We quantify interfacial thermal resistance through the calculation of the contribution of each functional group to the total heat flux, providing insights into the physical mechanisms governing heat transfer at functionalized interfaces. We demonstrated that manipulation of the concentrations of the functional groups can be used to tailor interfacial thermal transport.

physics.atm-clus↗

arXiv2025

Interfacial Behavior from the Atomic Blueprint: Machine Learning-Guided Design of Spatially Functionalized a-SiO2 Surfaces

a-Quartz surfaces functionalized with hydroxyl and methyl groups provide a versatile platform for controlling interfacial properties critical to applications such as catalysis, protective coatings, and energy conversion. The arrangement of these functional groups strongly influences interfacial interactions at solid-liquid interfaces, highlighting their relevance to colloid and interface science. However, conventional models often treat surface functionalization as spatially homogeneous, overlooking the atomic-scale organization of surface groups. We hypothesize that this spatial distribution, beyond overall composition, plays a decisive role in governing surface stability and interfacial behavior. To test this hypothesis, we employ a multi-scale simulation workflow combining density functional theory, ab initio molecular dynamics (AIMD), and machine-learned force fields (MLFFs). This approach allows us to explore a range of spatial patterns of OH/CH3 functionalization on the a-quartz (0001) surface. We evaluate the impact of spatial arrangements on mixing energy, hydrogen bonding networks, and vibrational properties with high accuracy and robustness. Our results reveal that spatial patterning strongly influences surface stability and interfacial structure. A thermodynamically favored unpaired configuration emerges near 67 % CH3 substitution, where isolated OH groups form secondary hydrogen bonds through reorientation toward subsurface oxygen atoms. This rearrangement induces a characteristic blue shift in OH stretching frequencies, indicating weaker H-bonding. These effects are absent in clustered arrangements. By establishing a clear link between functional group patterning and interfacial behavior, our work uncovers the underlying mechanisms to guide and accelerate the rational design of silica-based materials and coatings, directly relevant to colloid and interface science.

cond-mat.mtrl-sci↗

arXiv2024

Features of the Contact Angle Hysteresis at the Nanoscale: A Molecular Dynamics Insight

Understanding the physics of a three-phase contact line between gas, liquid, and solid is important for numerous applications. At the macroscale, the three-phase contact line response to an external force action is often characterized by a contact angle hysteresis, and several models are presented in the literature for its description. Yet, there is still a need for more information about such model applications at the nanoscale. In this study, a molecular dynamics approach was used to investigate the shape of a liquid droplet under an external force for different wetting regimes. In addition, an analytic model for describing the droplet shape was developed. It gives us the possibility to evaluate the receding and advancing wetting angle accurately. With our modeling, we found that the interplay between capillary forces and viscous forces is crucial to characterize the droplet shape at the nanoscale. In this frame, the importance of the rolling movement of the interface between liquid and vapor was pointed out. We also demonstrate that in the range of the external forces when capillary forces are most significant compared to others, hysteresis is well described by the macroscale Cox-Voinov model.

cond-mat.soft↗

arXiv2021

Molecular dynamics simulation of thermal transport across solid/liquid interface created by meniscus

Understandings heat transfer across a solid/liquid interface is important to develop new pathways to improve thermal management in various energy applications. One of the important questions that arises in this context is the impact of three-phase contact line between solid, liquid and gas on the perturbations of the heat fluxes at the nanoscale. Therefore, this paper is devoted to the investigations of features of thermal transport across nanosized meniscus constrained between two solid walls. Different wetting states of the meniscus were considered with molecular dynamics approach by the variation of the interactional potential between atoms of the substrate and the liquid. The effect of the size of the meniscus on the exchange of energy between two solid walls was also investigated. It was shown that the presence of a three phase contact line leads to a decrease of the interfacial boundary resistance between solid and liquid. Further, investigations with the finite element method were used to link atomistic simulations with the continuum mechanics. We demonstrate that the wetting angle and the interfacial boundary resistance are the required key-parameters to perform multiscale simulations of such engineering problems with an accurate microscale parametrization.

cond-mat.mes-hall↗