Article
Chemistry, Physical
Z. Rozynek, J. Banaszak, A. Mikkelsen, K. Khobaib, A. Magdziarz
Summary: Research shows that adding particles to the droplet interface significantly changes the parameters of electrorotation, such as deformation magnitude, orientation, and rotation rate. Experimental results indicate that the critical electric field and rotational rate for electrorotation depend on droplet size, particle shell morphology, and composition.
Article
Chemistry, Physical
K. Khobaib, A. Mikkelsen, T. Vincent-Dospital, Z. Rozynek
Summary: The study focuses on the deformation and yielding behavior of non-spherical Pickering droplets with arrested particle shells subjected to compressive stress, achieved by applying electric fields. The experimental results show that more aspherical droplets and/or droplets covered with larger particle shells require higher electric stress for deformation and yielding. Particle shells may fail through various crumpling instabilities, including ridge formation, folding, wrinkling, and inward indentation.
Article
Engineering, Chemical
Ning Li, Yunhui Pang, Zhiqian Sun, Yongxiang Sun, Zhuang Qi, Wangqing Li, Yue Liu, Bin Li, Zhenbo Wang, Hongbo Zeng
Summary: Polymers have a significant impact on the electrostatic demulsification efficiency of water-in-oil (W/O) emulsions by altering the motion characteristics of water droplets. The addition of polymers increases the polarity of the droplets, promoting their deformation and breakup under an electric field. The migration of polarized polymers and ions ultimately leads to droplet breakup.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Thermodynamics
Mingdong Ju, Bin Li, Wei Xiang, Zhentao Wang, Junfeng Wang
Summary: The electro-deformation and breakup dynamics of nanoparticle-laden droplets under electric fields were investigated using molecular dynamics simulations. It was found that SiO2 nanoparticles can stabilize the droplets and improve their stability. The droplet stability is higher under alternating current fields compared to direct current fields, and increasing the AC frequency enhances stability. These findings are valuable for optimizing the design of compact and efficient oil-water separators.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Engineering, Electrical & Electronic
Tomohiro Tsuji, Shigeomi Chono
Summary: Liquid crystal micromotors based on the backflow effect were developed, with the rotation speed of the inner cylinder controlled by the frequency and voltage of the applied electric field. The maximum rotation speed achieved was 20rpm, and the motor performance can be adjusted by changing the voltage and gap size.
SENSORS AND ACTUATORS A-PHYSICAL
(2021)
Article
Chemistry, Physical
Kelum Perera, Rony Saha, Pawan Nepal, Rohan Dharmarathna, Md Sakhawat Hossain, Md Mostafa, Alex Adaka, Ronan Waroquet, Robert J. Twieg, Antal Jakli
Summary: The experimental results and theoretical considerations of novel electromechanical effects of ferroelectric nematic liquid crystal droplets coexisting with the isotropic melt are presented in this study. It is found that the droplets have flat pancake-like shapes thinner than the sample thickness. A wing-shaped defect with low birefringence is present in the center of the droplets, moving perpendicular to a weak electric field, and dividing into two at higher fields. The entire droplet drifts along the electric field with a speed independent of droplet size and proportional to the electric field amplitude.
Article
Engineering, Chemical
Xin Huang, Xiaoming Luo, Yunrui Han, Weidong Li, Yuekun Lai, Lin Teng
Summary: The deformation and breakup behaviors of droplets containing polymer were investigated to understand the mechanism of electric field collapse during the treatment of emulsion containing polymer. The results showed that the electric field collapse process caused by droplet breakup consists of three steps, and the increase of polymer concentration strengthens the Joule heating effect.
Article
Mechanics
Daorui Wang, Junfeng Wang, Dongbao Wang, Lei Zuo, Jian Gao, Haojie Xu
Summary: The conical breakup behavior of droplets in immiscible dielectric liquids under non-uniform alternating current (AC) electric fields is experimentally investigated using high-speed photography. Two distinct conical breakup configurations, called the trident vibration and lotus vibration modes, are proposed, and their detailed structural parameters are discussed. The extremely small stable conical meniscus is found in the liquid-liquid system. The multilevel asymptotic characteristics of conical fragmentation are observed due to the variances in spatial and temporal scales.
Article
Chemistry, Multidisciplinary
Anna Sinelnikova, Thomas Mandl, Christofer Ostlin, Oscar Granas, Maxim N. Brodmerkel, Erik G. Marklund, Carl Caleman
Summary: Proteins' dynamics are crucial for their function, but current techniques have limitations in monitoring high-resolution time-resolved dynamics. Combining electric fields with existing techniques may open up a new era for studying gas-phase protein dynamics.
Article
Mathematics, Applied
Zdzislaw Brzezniak, Gabriel Deugoue, Paul Andre Razafimandimby
Summary: This paper considers the 2D Ericksen-Leslie equations which describe the hydrodynamics of nematic liquid crystal with external body forces and anisotropic energy. Global weak solutions with finitely many singular times are proven under general assumptions, and it is also established that the global weak solution is regular as long as the data are regular and the initial data and external forces are sufficiently small.
JOURNAL OF EVOLUTION EQUATIONS
(2021)
Review
Chemistry, Physical
Jingwen Li, Weinan Yin, Junan Pan, Yingbo Zhang, Fengshun Wang, Longlu Wang, Qiang Zhao
Summary: Hydrogen is expected to replace traditional fossil energy as a clean, efficient, and sustainable energy source. The external field-assisted hydrogen evolution reaction (HER) has become a new research hotspot, and this article provides a systematic summary of the promoting effects of various external fields on catalytic hydrogen production. It discusses the challenges and future research topics in this field.
Article
Materials Science, Multidisciplinary
Cunquan Li, Yukai An
Summary: The Janus 2H-VTeSe monolayer, as an intrinsic ferromagnetic semiconductor, exhibits excellent physicochemical properties and has potential applications in optoelectronics, valley electronics, and nanoelectronics. Its properties can be effectively tuned by biaxial strain and charge carrier doping.
Article
Chemistry, Physical
Ruizhi Yang, Yueming Deng, Shuting Xie, Mengjun Liu, Yiying Zou, Tiezheng Qian, Qi An, Jiamei Chen, Shitao Shen, Albert van den Berg, Minmin Zhang, Lingling Shui
Summary: We report a three-dimensional system based on liquid crystal droplets (LCDs) for controllable and reversible ingestion and release of guest aqueous droplets (GADs). Microscale LCDs ingest external components and transform them into radially assembled tiny GADs inside the LCDs, driven by interfacial thermodynamic fluctuations and internal topological defects. The release of ingested GADs can be actively triggered by changing the anchoring conditions at the interface of the LCDs. These controllable processes can occur at room temperature and neutral pH without additional energy input, providing a unique and viable route for constructing hierarchical 3D structures.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Chemistry, Physical
Jun Zhang, Ying Xiang, Xiaoyu Ding, Luguo Hao, Supreet Kaur, Golam Mohiuddin, Santanu Kumar Pal, Peter Salamon, Nandor Eber, Agnes Buka
Summary: The study explores the response of a newly synthesized hockey-stick nematic 8-F-OH to applied electric field, revealing unusual pattern forming scenarios that vary with frequency, temperature, and initial director alignment. The behavior is compared with calamitic and bent-core nematics, highlighting the crucial role of elastically deformed layers in pattern formation, especially in the presence of polar smectic clusters.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Physics, Fluids & Plasmas
Gregory Kozyreff, Benny Davidovitch, S. Ganga Prasath, Guillaume Palumbo, Fabian Brau
Summary: Recent studies have focused on the capillary interaction between a liquid drop and a thin solid sheet of low bending stiffness. Wetting behavior is discussed as a function of applied tension using numerical, variational, and asymptotic techniques. Complete wetting is possible for wettable surfaces with a defined Young's contact angle below a critical applied tension. A vesicle forms in the sheet at intermediate tensions, enclosing most of the fluid, and the shape of the drop is determined by the ratio of area to a tension-dependent bendocapillary length.
Article
Chemistry, Multidisciplinary
Quinn A. Besford, Holger Merlitz, Simon Schubotz, Huaisong Yong, Soosang Chae, Max J. Schnepf, Alessia C. G. Weiss, Guenter K. Auernhammer, Jens-Uwe Sommer, Petra Uhlmann, Andreas Fery
Summary: This study reports on ultrathin polymer brush surfaces integrated with single fluorophores, which exhibit changing fluorescence properties based on polymer conformation. Fluorescence lifetime imaging microscopy is used to reveal spatial details on polymer brush conformational transitions across complex interfaces and enables high-resolution surface-based sensing of stimuli-induced phase transitions of polymer brushes.
Article
Chemistry, Multidisciplinary
William S. Y. Wong, Doris Vollmer
Summary: This study presents the concept of passive on-demand recovery of the plastron through a chemical reaction (effervescence), offering a new approach for intervention-free and immersion-durable superhydrophobic/superamphiphobic surfaces.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Chander Shekhar Sharma, Athanasios Milionis, Abhinav Naga, Cheuk Wing Edmond Lam, Gabriel Rodriguez, Marco Francesco Del Ponte, Valentina Negri, Hopf Raoul, Maria D'Acunzi, Hans-Juergen Butt, Doris Vollmer, Dimos Poulikakos
Summary: The study found that infusing a large amount of lubricant in PDMS can significantly reduce viscoelastic dissipation in the substrate, increase droplet nucleation density, and accelerate the occurrence of the cloaking effect, thereby enhancing the condensation process and increasing the dewing on the substrate.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Review
Chemistry, Physical
Hans-Jurgen Butt, Jie Liu, Kaloian Koynov, Benedikt Straub, Chirag Hinduja, Ilia Roismann, Rudiger Berger, Xiaomei Li, Doris Vollmer, Werner Steffen, Michael Kappl
Summary: Contact angle hysteresis is essential for providing friction to drops and is caused by the nanoscopic structure of surfaces. Understanding and measuring contact angle hysteresis and developing surfaces with low contact angle hysteresis are crucial for various applications.
CURRENT OPINION IN COLLOID & INTERFACE SCIENCE
(2022)
Article
Mechanics
Peyman Rostami, Guenter K. Auernhammer
Summary: The merging of immiscible drops differs from that of miscible drops due to the formation of a liquid-liquid interface. The four-phase contact point between drops, gas, and substrate exhibits its own distinct dynamics, which have not been studied before. The propagation distance of this point follows a t(1/2) scaling with time for various scenarios, and a model balancing driving and dissipative forces agrees with experimental results.
Article
Chemistry, Physical
Philipp Baumli, Lukas Hauer, Emanuela Lorusso, Azadeh Sharifi Aghili, Katharina Hegner, Maria D'Acunzi, Jochen S. Gutmann, Burkhard Duenweg, Doris Vollmer
Summary: External shear flows of oil lead to linear dehydration and shrinkage of hydrogel due to finite solubility of water in oil continuously removing water from the hydrogel by diffusion. The flow advects the water-rich oil, as demonstrated by numerical solutions, and shear does not cause gel shrinkage for water-saturated oils or non-solvents. The solubility of water in the oil will tune the dehydration dynamics.
Article
Biochemistry & Molecular Biology
Quinn A. Besford, Simon Schubotz, Soosang Chae, Ayse B. Ozdabak Sert, Alessia C. G. Weiss, Gunter K. Auernhammer, Petra Uhlmann, Jose Paulo S. Farinha, Andreas Fery
Summary: This article introduces a brush system for studying molecular transport from droplets to external polymer brushes. The study finds that molecular transport is influenced by relative humidity.
Article
Chemistry, Physical
Rodrique G. M. Badr, Lukas Hauer, Doris Vollmer, Friederike Schmid
Summary: We investigated the equilibrium properties and wetting behavior of a liquid on a polymer brush using Dissipative Particle Dynamics simulations. We studied the effects of grafting density and lubricant presence on the behavior of the brush. Additionally, we examined the wetting behavior of a droplet on the brush and found that the lubricant can completely cover the droplet's surface. We also proposed a thermodynamic theory to explain this behavior.
JOURNAL OF PHYSICAL CHEMISTRY B
(2022)
Article
Chemistry, Multidisciplinary
Chirag Hinduja, Alexandre Laroche, Sajjad Shumaly, Yujiao Wang, Doris Vollmer, Hans-Jurgen Butt, Rudiger Berger
Summary: By using scanning drop friction force microscopy (sDoFFI), we can obtain 2D wetting maps of samples and localize inhomogeneities and image wetting variations. sDoFFI is a new tool for characterizing laboratory-based, biological, and commercial surfaces.
Article
Materials Science, Multidisciplinary
Eric Langner, Denise Gruner, Ramona Mehling, Franziska Obst, Adrian Ehrenhofer, Stefan Gruenzner, Gunter K. Auernhammer, Stefan Michel, Andreas Richter, Thomas Wallmersperger
Summary: This study investigates the control of hydrogel pores with swelling and de-swelling capabilities, and analyzes the effects of microfluidic pressure and gel volume on the pores. Experimental and numerical investigations show that the swelling behavior can be described using a temperature expansion model and a neohookean material description, and the bending influence on the pores under pressure can be negligible. The results have good agreement between numerical and experimental results, demonstrating the potential for geometric optimization of hydrogel pores.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2023)
Editorial Material
Physics, Multidisciplinary
Doris Vollmer, Roland J. -R. Bednarz, Sebastian Seiffert, Beatrice Bednarz
Summary: There is an urgent need to rethink the Nobel Prize in Physics in order to acknowledge research that addresses pressing challenges for humanity.
Article
Chemistry, Physical
Ankita De, Sattwick Haldar, Stefan Michel, Leonid Shupletsov, Volodymyr Bon, Nikolaj Lopatik, Lili Ding, Lukas M. Eng, Gunter K. Auernhammer, Eike Brunner, Andreas Schneemann
Summary: This study explores the tunability of covalent organic frameworks (COFs) and their processability. Anchoring alkoxy side chains to the COF backbone elongates the interlayer distance, leading to the successful exfoliation into nanosheets. The nanosheets show stability in dispersion, hydrophobic surface properties, and potential applications in lithium-ion battery separators.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Physical
Peyman Rostami, Mohammad Ali Hormozi, Olaf Soltwedel, Reza Azizmalayeri, Regine von Klitzing, Guenter K. Auernhammer
Summary: We investigated the wetting properties of PDMS pseudo-brush anchored on glass substrates, which exhibited lower contact angle hysteresis compared to hydrophobic silanized substrates. The effect of different molar masses of PDMS on the wetting properties was found to be negligible. The extremely smooth surface of the PDMS pseudo-brush explained the reduction in contact angle hysteresis and made it useful for wetting experiments. The dynamics of the four-phase contact point on PDMS pseudo-brushes were substantially different from other substrates, with changes depending only slightly on the molar mass of PDMS, leading to increased traveling speed and a different power law of position vs time.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Simon Schubotz, Quinn A. Besford, Saghar Nazari, Petra Uhlmann, Eva Bittrich, Jens-Uwe Sommer, Gunter K. Auernhammer
Summary: Polymer brushes, which are polymer chains tethered to substrates, are highly sensitive to adaptation and can undergo changes in swelling, adsorption, and reorientation due to the surrounding liquid or atmosphere. This study analyzes how the atmosphere surrounding an aqueous droplet affects the contact angle on polymer brush surfaces. The use of a coaxial needle allows for reliable measurement of wetting properties even when the droplet and atmosphere are not in equilibrium. It was found that the water contact angle of a sample can be significantly influenced by the composition and humidity of the surrounding atmosphere.
Article
Engineering, Environmental
Panlong Li, Niklas Unglaube, Hanfeng Zhou, Stefan Michel, Xiaoli Dong, Xiaosa Xu, Anja Birnbaum, Guenter K. Auernhammer, Yongyao Xia, Julia Grothe, Stefan Kaskel
Summary: Ion-controlled electronics utilize biocompatible electrolytes to achieve various functions and have great potential for biological applications. However, the presence of high-content water-soluble ionic impurities in commercial and custom designed carbons affects their capacitive behavior in pure water electrolyte, as well as the precise control of ion transport. This study analyzes the influence of adsorbed ionic impurities on the electrosorption mechanism in a low concentrated bioactive electrolyte, and highlights the importance of these impurities for the properties and applications of carbon materials.
CHEMICAL ENGINEERING JOURNAL
(2023)
