Miguel A. Rodríguez-Valverde

Miguel A. Rodríguez-Valverde
University of Granada | UGR · Department of Applied Physics

Ph. Doctor

About

93
Publications
32,218
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,763
Citations
Citations since 2016
28 Research Items
1130 Citations
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150
Introduction
Design of nonsticky coatings Interfacial behavior of Janus nanoparticles Colloidal patterning via convective assembly Interfacial behavior of bitumen in aqueous medium at high temperatures Biomimetic apatite coatings on titanium surfaces Contact angle hysteresis and most-stable contact angle
Additional affiliations
October 2015 - present
University of Granada
Position
  • Professor (Associate)
October 2015 - present
University of Granada
Position
  • Professor (Associate)
April 2011 - October 2015
University of Granada
Position
  • Lecturer

Publications

Publications (93)
Article
Full-text available
Elastomeric surfaces and oil-infused elastic surfaces reveal low ice adhesion, in part because of their deformability. However, these soft surfaces might jeopardize their mechanical durability. In this work, we analyzed the mechanical durability of elastic polydimethylsiloxane (PDMS) surfaces with different balances between elasticity and deicing p...
Article
Hypothesis Ice adhesion to rigid materials is reduced with low energy surfaces of high receding contact angles. However, their adhesion strength values are above the threshold value to be considered as icephobic materials. Surface deformability is a promising route to further reduce ice adhesion. Experiments In this work, we prepared elastomer sur...
Article
Elucidating the predominant factors for the freezing delay of surfaces is still a matter of discussion and controversy. Freezing delay is explained in literature through the classical nucleation theory. It postulates that freezing delay of a surface is enhanced with low surface roughness and sessile drops of high contact angles. However, since surf...
Article
Hypothesis Characterization of contact angle hysteresis on soft surfaces is sensitive to the measurement protocol and might present adventitious time-dependencies. Contact line dynamics on solid surfaces is altered by the surface chemistry, surface roughness and/or surface elasticity. We observed a “slow” spontaneous relaxation of static water sess...
Article
Full-text available
Aluminum-magnesium (Al-Mg) alloy and aluminum-coated steel (aluminized steel) are typically used for the manufacturing of baking trays and molds. For these applications, these materials must be modified to develop release and hydrophobic properties. With this aim, the bare substrates are typically coated with low-surface energy materials such as fl...
Article
Full-text available
Evaporating salty droplets are ubiquitous in nature, in our home and in the laboratory. Interestingly, the transport processes in such apparently simple systems differ strongly from evaporating “freshwater” droplets since convection is partly inverted due to Marangoni stresses. Such an effect has crucial consequences to the salt crystallization pro...
Article
Full-text available
Fluoropolymer-based coatings are widely used for release applications. However, these hydrophobic surfaces do not reveal a significantly low adhesion. Water repellency incorporated to fluoropolymer coatings might enhance their release performance. In this work, we focused on the surface texturing of a well-known polytetrafluoroethylene (PTFE)-based...
Article
Full-text available
Evaluation of superhydrophobic (SH) surfaces based on contact angle measurements is challenging due to the high mobility of drops and the resolution limits of optical goniometry. For this reason, some alternatives to drop-shape methods have been proposed such as the damped-oscillatory motion of ferrofluid sessile drops produced by an external magne...
Article
In this work, we studied the wettability of hydrophobic surfaces fabricated with three different materials (PTFE, PDMS and paraffin wax) over a wide range of roughness. We estimated the Advancing, Receding and Most-Stable contact angles and we identified the transition from a homogeneous wetting regime (Wenzel) to a hybrid wetting regime (Cassie-Ba...
Article
Hypothesis Wettability of solid surfaces is mostly probed with sessile drops rather than bubbles because this method is readily followed out. This recurrent use may lead to a misleading connection of certain phenomena to the hydrophobicity/hydrophilicity of materials. For instance, the Cassie-Baxter regime and the wicking effect are generally assoc...
Preprint
Full-text available
Evaporating salty droplets are ubiquitous in nature, in our home and in the laboratory. Interestingly, the transport processes in such apparently simple systems differ strongly from evaporating "freshwater" droplets since convection is partly inverted due to Marangoni stresses. Such an effect has crucial consequences to the salt crystallization pro...
Article
Full-text available
The manufacturing of polyurethane foam is a process of great industrial importance in the automotive and furniture sector. The operation of demolding is the most delicate, since the foam sticks firmly to the walls of the mold onto which it has spread. In order to avoid the use of demolding agents, the proposal is to coat the inside of the molds wit...
Article
Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in industry. The wettability of the produced surface was analyzed by bouncing drop experiments and the topography was analyzed by confocal microscopy. In addition, we show various methodologies to measur...
Article
The analysis of wetting properties of superhydrophobic surfaces may be a difficult task due to the restless behavior of drops on this type of surfaces and the limitations of goniometry for high contact angles. A method to validate the performance of superhydrophobic surfaces, rather than standard goniometry, is required. In this work, we used bounc...
Article
One of the main challenges in cookware and baking industry is the fabrication of enhanced nonstick coatings including two main features: highly hydrophobic, resistant and durable. In general, life-long release coatings are prepared with a polymer-filler composite of several microns thickness deposited on food-compatible metals such as aluminum, sta...
Article
Particles adsorbed at liquid interfaces are commonly used to stabilise water-oil Pickering emulsions and water-air foams. The fundamental understanding of the physics of particles adsorbed at water-air and water-oil interfaces is improving significantly due to novel techniques that enable the measurement of the contact angle of individual particles...
Patent
Full-text available
The present invention refers to a procedure that allows to obtain useful data when determining the non-stick capacity of a coating or surface. In particular, this procedure carries out a device which is also an object of the invention.
Article
Full-text available
Titanium implant surface etching has proven an effective method to enhance cell attachment. Despite the frequent use of hydrofluoric (HF) acid, many questions remain unresolved, including the optimal etching time and its effect on surface and biological properties. The objective of this study was to investigate the effect of HF acid etching time on...
Article
Colloidal interactions have been extensively studied due to the wide number of applications where colloids are present. In general, the electric double layer force and the van der Waals interaction dominate the net force acting between two colloids at large separation distances. However, it is well accepted that some other phenomena, especially tho...
Article
Full-text available
Gold patchy nanoparticles (PPs) were prepared under surfactant-free conditions by functionalization with a binary ligand mixture of polystyrene and poly(ethylene glycol) (PEG) as hydrophobic and hydrophilic ligands, respectively. The interfacial activity of PPs was compared to that of homogeneous hydrophilic nanoparticles (HPs), fully functionalize...
Article
Polymethylmethacrylate/Poly-tert-butylmethacrylate Janus nanoparticles were synthesized by the electrohydrodynamic co-jetting method. The Janus character of these nanoparticles was visualized through super-resolution imaging with Structured Illumination Microscopy. The Janus nanoparticles, and the corresponding homogeneous sets, were then morpholog...
Article
Full-text available
Gold patchy nanoparticles (PPs) were prepared under surfactant-free conditions by functionalization with a binary ligand mixture of polystyrene and poly(ethylene glycol) (PEG) as hydrophobic and hydrophilic ligands, respectively. The interfacial activity of PPs was compared to that of homogeneous hydrophilic nanoparticles (HPs), fully functionalize...
Article
The design of durable superhydrophobic coatings for metal surfaces is a subject of interest and research. Galvanized steel is one of the most used metallic materials for components of automobiles, building structures and roofing. In spite of its wide number of applications, galvanized steel has been scarcely modified to reach superhydrophobicity. T...
Article
Titanium is extensively employed in biomedical devices, in particular as implant. The self-assembly of alkylphosphonates on titanium surfaces enable the specific adsorption of biomolecules to adapt the implant response against external stimuli. In this work, chemically-tailored cpTi surfaces were prepared by self-assembly of alkylphosphonate molecu...
Article
The motion of electrically charged particles under crowding conditions and subjected to evaporation-driven capillary flow might be ruled by collective diffusion. The concentration gradient developed inside an evaporating drop of colloidal suspension may reduce by diffusion the number of particles transported toward the contact line by convection. U...
Article
Full-text available
Janus gold nanoparticles (JPs) of ∼4 nm-diameter half functionalized with 1-hexanethiol as a hydrophobic capping ligand exhibit significantly higher interfacial activity, reproducibility and rheological response when the other half is functionalized with 1,2-mercaptopropanediol (JPs-MPD) than with 2-(2-mercaptoethoxy)ethanol (JPs-MEE), both acting...
Article
Surface heterogeneity affects the behavior of nanoparticles at liquid interfaces. To gain deeper understanding on the details of these phenomena, we have measured the interfacial activity and contact angle at water/decane interfaces for three different types of nanoparticles: homogeneous PMMA, silica functionalized with a capping ligand containing...
Article
Segregation of particles during capillary/convective self-assembly is interesting for self-stratification in colloidal deposits. In evaporating drops containing colloidal particles, the wettability properties of substrate and the sedimentation of particles can affect their accumulation at contact lines. In this work we studied the size segregation...
Article
We present results for the most stable contact angle using a numerical implementation of the tilting plate method of Montes et al. (Montes Ruiz-Cabello, F. J.; Rodriguez-Valverde, M. A.; Cabrerizo-Vilchez, M. Soft Matter 2011, 7, 10457–10461). Comparison with the experimental results is made, obtaining a good agreement in most situations. In additi...
Article
Full-text available
Complete understanding of colloidal assembly is still a goal to be reached. In convective assembly deposition, the concentration gradients developed in evaporating drops or reservoirs are usually significant. However, collective diffusion of charge-stabilized particles has been barely explored. The balance between convective and diffusive flows may...
Article
An entropic segmentation method is presented and applied to the contour detection of water drops over patterned surfaces. Jensen–Shannon divergence is computed from a double sliding window in the image to get a real number matrix, in which a region growing procedure is performed in a similar way to usual watershed. Then a region merging process is...
Article
Full-text available
In hot asphalt applications, the adhesion between bitumen and mineral aggregate is usually described in terms of bitumen surface tension and contact angle of the bitumen over the aggregate. However, the quantification of the physico-chemical bond between bitumen and aggregate under realistic conditions is a nontrivial task. In this work, we designe...
Article
Full-text available
The oxidation state of the surfaces of titanium-based biomaterials strongly depends on their previous history. This factor affects the titanium wettability and it probably conditions the success of the implanted biomaterials. However, the separate role of the pollution and oxidation states of metallic titanium surfaces remains still controversial....
Article
Better control of colloidal assembly by convective deposition is particularly helpful in particle templating. However, knowledge of the different factors that can alter colloidal patterning mechanisms is still insufficient. Deposit morphology is strongly ruled by contact line dynamics, but the wettability properties of the substrate can alter it dr...
Article
The structure and orientation of nanoparticles at the liquid–liquid interface may be useful for the preparation of robust, self-assembled structures, devices, and membranes. The pendant drop technique enables to study the interfacial activity of nanoparticles with smaller amounts and upon more controlled conditions than with the traditional Langmui...
Article
It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most st...
Article
Complexation of DNA with lipids is currently being developed as an alternative to classical vectors based on viruses. Most of the research to date focuses on cationic lipids owing to their spontaneous complexation with DNA. Nonetheless, recent investigations have revealed that cationic lipids induce a large number of adverse effects on DNA delivery...
Article
Full-text available
In this work we report an experimental study on the surface activity and the collective behaviour of colloidally stable Janus-like silver particles at the air-water interface. The colloidal stability of silver nanoparticles has been enhanced using different capping ligands. Two polymers coated the silver particles: 11-mercaptoundecanoic acid and 1-...
Article
The interfacial activity of 3.5 nm homogeneous (HPs) and amphiphilic Janus gold nanoparticles (JPs) was characterized by pendant drop tensiometry for water/air and water/decane interfaces. This technique requires a lower quantity of nanoparticles than the traditional Langmuir balance technique. The direct deposition at the interface of the nanopart...
Article
Abstract The impact of the interfacial properties of naphthenic bitumen is very relevant for road paving. In this work, we propose an approach for predicting the interfacial energy of bitumen in aqueous media based on contact angle hysteresis measurements. We measured the surface tension of naphthenic bitumen at high temperature with the pendant dr...
Poster
The ongoing scaling process in the integrated circuits industry presents a problem of increasing importance: the pattern collapse [1, 2]. In order to develop a support tool to understand capillary rise and pattern collapse, with many other applications in fiber and hair wetting, we designed a numerical model based on Surface Evolver to predict the...
Poster
The implementation of soft matter physics in the design of biomimetic materials is an exciting and emerging field in material sciences. The chemical tailoring of titanium surfaces with self-assembled monolayers of organophosphonates enables to reach an optimal range of biofunctions in a biomaterial [1]. The functionalized surface with this strategy...
Article
We study the pattern formation induced by drying colloidal suspensions and polymer solutions in a vertical Hele-Shaw cell immersed in a reservoir. The contact line speed is controlled by pumping out the solution from the reservoir. At low capillary number stick–slip motion of the receding contact line can be observed for silica suspensions. Periodi...
Article
Full-text available
In order to produce well-ordered structures via evaporation, it is essential to control the evaporation flux, solute concentration, interaction between the solute and the substrate, etc. During the drying of particle suspensions, the particle deposition process can be dictated by electrostatic and van der Waals forces. However, the complex physics...
Article
Owing to contact angle hysteresis, the contact angle that a sessile drop adopts on a surface can be quite different depending on the process of drop formation. This is particularly noticeable for receding contact angle because it is most susceptible to the details of the measuring method. We performed low-rate dynamic contact angle experiments with...
Article
We propose to measure the most accurate contact angle for calculation of solid surface tensions from the most mechanically stable drop. From tilting plate experiments, we probed the sliding behavior of sessile drops with equal volume but different contact angle. We measured two critical tilt angles for each drop. When the surface was tilted beyond...
Article
Currently, there is no conclusive evidence regarding the global equilibrium condition of vibrated drops. However, it is well-known that vibration of sessile drops effectively reduces the contact angle hysteresis. In this work, applying a recent methodology for evaluating the most-stable contact angle, we examined the impact of the type of excitatio...
Article
Quasi-static experiments using sessile drops and captive bubbles are the most employed methods for measuring advancing and receding contact angles on real surfaces. These observable contact angles are the most easily accessible and reproducible. However, some properties of practical surfaces induce certain phenomena that cause a built-in uncertaint...
Article
After the impact of the great review of M. Strobel and C. S. Lyons on contact angle measurements, we discuss some claims of the authors. The Wilhelmy method is not generally “the best technique for measuring the contact angle hysteresis” as the authors claimed. Otherwise, we think that, even though equilibrium contact angle is an “unattainable” ang...
Article
We propose a new method for the direct measurement of the moststable contact angle, using the mechanical vibration of sessile drops from different metastable states. We relaxed sessile drops of identical volume but with different stable contact angles between advancing and receding configurations. Before the vibration, we were able to scan the rang...
Article
In order to characterize a solid surface, the commonly used approach is to measure the advancing and receding contact angles, i.e., the contact angle hysteresis. However, often an estimate of the average wettability of the solid-liquid system is required, which involves both the dry and wetted states of the surface. In this work, we measured advanc...
Article
The capillary rise/fall of a liquid within a thin capillary tube is described by the well-established Jurin's law. The liquid reaches an equilibrium height/depth as the capillary pressure is balanced by the hydrostatic pressure. When the adhesion force at the three-phase contact line is counteracted by the liquid weight, the liquid column also stab...
Article
Texturization of surfaces is usually advantageous in biomaterial engineering. However, the details of the textured surfaces can be more determining on cell adhesion and proliferation, rather than their roughness degree. Titanium is extensively used as a dental implant material in the human body. In this paper, the effect of four surface treatments...
Article
Beyond the linear model of Schulze et al. [J. Adhes. Sci. Technol. 3 (1)(1989)39-48], a more comprehensive model for predicting the Young contact angle of rough and chemically homogeneous surfaces from contact angle hysteresis measurements is proposed. This new model incorporates the barrier effect, described by Shuttleworth and Bailey, and the Wen...
Conference Paper
A new approach to image segmentation based on entropic region growing and merging, which is useful in drop shape analysis, is presented in this paper. The procedure works in three steps. First, a normalized divergence matrix is obtained which gives the likelihood of being a boundary pixel for each pixel in the image. Second, a region growing algori...
Article
Full-text available
We model an infinitely long liquid bridge confined between two plates chemically patterned by stripes of the same width and different contact angle, where the three-phase contact line runs, on average, perpendicular to the stripes. This allows us to study the corrugation of a contact line in the absence of pinning. We find that, if the spacing betw...
Article
Full-text available
Vector algebra is a powerful and needful tool for Physics but unfortunately, due to lack of mathematical skills, it becomes misleading for first undergraduate courses of science and engineering studies. Standard vector identities are usually proved using Cartesian components or geometrical arguments, accordingly. Instead, this work presents a new t...
Article
Full-text available
The proportionality constant in Ohm's law is the electrical resistance. The resistance of conducting objects depends on their geometrical features such as cross-sectional area and length. Since the cross-sectional area of resistors usually varies as its length, the calculation of resistances is a non-trivial task. In this letter, a closed-form inte...