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Dive into the research topics where M. Rajňák is active.

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Featured researches published by M. Rajňák.


Materials | 2017

Electric Field-Driven Assembly of Sulfonated Polystyrene Microspheres

Alexander Mikkelsen; Jarosław Wojciechowski; M. Rajňák; Juraj Kurimský; Khobaib Khobaib; Ahmet Kertmen; Zbigniew Rozynek

A designed assembly of particles at liquid interfaces offers many advantages for development of materials, and can be performed by various means. Electric fields provide a flexible method for structuring particles on drops, utilizing electrohydrodynamic circulation flows, and dielectrophoretic and electrophoretic interactions. In addition to the properties of the applied electric field, the manipulation of particles often depends on the intrinsic properties of the particles to be assembled. Here, we present an easy approach for producing polystyrene microparticles with different electrical properties. These particles are used for investigations into electric field-guided particle assembly in the bulk and on surfaces of oil droplets. By sulfonating polystyrene particles, we produce a set of particles with a range of dielectric constants and electrical conductivities, related to the sulfonation reaction time. The paper presents diverse particle behavior driven by electric fields, including particle assembly at different droplet locations, particle chaining, and the formation of ribbon-like structures with anisotropic properties.


Materials | 2017

Assembly of 1D Granular Structures from Sulfonated Polystyrene Microparticles

Alexander Mikkelsen; Ahmet Kertmen; Khobaib Khobaib; M. Rajňák; Juraj Kurimský; Zbigniew Rozynek

Being able to systematically modify the electric properties of nano- and microparticles opens up new possibilities for the bottom-up fabrication of advanced materials such as the fabrication of one-dimensional (1D) colloidal and granular materials. Fabricating 1D structures from individual particles offers plenty of applications ranging from electronic sensors and photovoltaics to artificial flagella for hydrodynamic propulsion. In this work, we demonstrate the assembly of 1D structures composed of individual microparticles with modified electric properties, pulled out of a liquid environment into air. Polystyrene particles were modified by sulfonation for different reaction times and characterized by dielectric spectroscopy and dipolar force measurements. We found that by increasing the sulfonation time, the values of both electrical conductivity and dielectric constant of the particles increase, and that the relaxation frequency of particle electric polarization changes, causing the measured dielectric loss of the particles to shift towards higher frequencies. We attributed these results to water adsorbed at the surface of the particles. With sulfonated polystyrene particles exhibiting a range of electric properties, we showed how the electric properties of individual particles influence the formation of 1D structures. By tuning applied voltage and frequency, we were able to control the formation and dynamics of 1D structures, including chain bending and oscillation.


Acta Physica Polonica A | 2014

Viscosity Dependence of a Magnetic Fluid Nanoparticles Concentration

Jana Tóthová; J. Kováč; P. Kopčanský; M. Rajňák; K. Paulovičová; M. Timko; A. Józefczak


Acta Physica Polonica A | 2014

Influence of Magnetic Field on Dielectric Breakdown in Transformer Oil Based Ferrofluids

M. Rajňák; Juraj Kurimský; Bystrík Dolník; K. Marton; L. Tomčo; Matus Molcan; P. Kopčanský; M. Timko


Journal of Materials Science | 2018

Rapid mechanochemical synthesis of nanostructured mohite Cu2SnS3 (CTS)

Matej Baláž; Nina Daneu; M. Rajňák; Juraj Kurimský; Michal Hegedüs; Erika Dutková; Martin Fabián; Mária Kaňuchová; Peter Baláž


Journal of Electrostatics | 2017

Magnetic fluid droplet deformation in electrostatic field

Roman Cimbala; Juraj Kurimský; M. Rajňák; Katarína Paulovičová; M. Timko; P. Kopčanský; Michal Kolcun; Michal Kosterec; Samuel Bucko; Mária Kurimská


Acta Physica Polonica A | 2018

Variation of Magnetic Fluid Deformation Related to Nanoparticle Concentration in Steady Electric Field

Michal Kosterec; Juraj Kurimský; Roman Cimbala; M. Špes; R. Farkaš; Bystrík Dolník; M. Gamcová; M. Rajňák; M. Timko; P. Kopčanský; K. Paulovičová; B. Vargová


Acta Physica Polonica A | 2018

Influence of Electric Field on AC Magnetic Susceptibility of a Mineral Oil Based Ferrofluid

M. Rajňák; Bystrík Dolník; T. Tobiáš; K. Paulovičová; Juraj Kurimský; Roman Cimbala; P. Kopčanský; M. Timko


Acta Physica Polonica A | 2018

The Shielding Effectiveness of a Magnetic Fluid in Radio Frequency Range

Bystrík Dolník; M. Rajňák; Roman Cimbala; I. Kolcunová; Juraj Kurimský; J. Džmura; J. Petráš; J. Zbojovský; Michal Kosterec; P. Kopčanský; M. Timko


Acta Physica Polonica A | 2017

Ultrasound Frequency Analysis of a Magnetic Fluid in Low-Intensity External Magnetic Field

Juraj Kurimský; M. Rajňák; Roman Cimbala; Bystrík Dolník; J. Tóthová; K. Paulovičová; M. Timko; P. Kopčanský; I. Kolcunová; J. Petráš; J. Džmura; J. Balogh

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Juraj Kurimský

Technical University of Košice

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M. Timko

Slovak Academy of Sciences

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P. Kopčanský

Slovak Academy of Sciences

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Bystrík Dolník

Technical University of Košice

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Roman Cimbala

Technical University of Košice

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K. Paulovičová

Slovak Academy of Sciences

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Michal Kosterec

Technical University of Košice

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Jana Tóthová

Technical University of Košice

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L. Tomčo

Slovak Academy of Sciences

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Michal Kolcun

Technical University of Košice

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