Nerea Sebastián

Nerea Sebastián
Jožef Stefan Institute | IJS · Complex Matter

PhD

About

53
Publications
6,336
Reads
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812
Citations
Additional affiliations
October 2016 - September 2018
Jožef Stefan Institute
Position
  • Marie Skłodowska-Curie Postdoctoral Fellow
September 2014 - August 2016
Otto-von-Guericke-Universität Magdeburg
Position
  • Humboldt Research Fellow
January 2013 - August 2014
Universidad del País Vasco / Euskal Herriko Unibertsitatea
Position
  • PostDoc Position
Education
September 2008 - November 2012
September 2003 - July 2008

Publications

Publications (53)
Preprint
Full-text available
Sessile droplets of a ferroelectric nematic liquid crystalline material were exposed to surface electric fields produced by pyroelectric and photogalvanic (photovoltaic) effects in X-cut iron-doped lithium niobate crystals. The resulting dynamic processes were monitored by polarization optical (video)microscopy (POM). During heating/cooling cycles,...
Article
Ferrofluids are colloidal suspensions of magnetic nanoparticles. Ferromagnetic ordering – with spontaneous net magnetization in the absence of external fields – has been described for a system of permanently magnetic nanoplatelets suspended in n-butanol, concentrated enough to undergo the transition to the nematic phase. Such material shows magneti...
Preprint
Full-text available
We investigated the effect of a photovoltaic field generated on the surface of iron-doped lithium niobate crystals on droplets of a ferroelectric nematic liquid crystalline and a standard nematic liquid crystalline material deposited on this surface. When such assembly is illuminated with a laser beam, a wide range of dynamic phenomena are initiate...
Article
Dense dispersions of ferrimagnetic bariumhexaferrite nanoplatelets form colloidal nematic phases even in the isotropic solvent such as n-butanol. The transition into the nematic phases is marked by developing the long-range orientational and magnetic correlations between the particles. Here we explore the magnetic dynamics in such dispersions in th...
Preprint
Recent experimental realization of ferroelectric nematic liquid crystalline phases stimulated material development and numerous experimental studies of these new phases, guided by their fundamental and applicative interest. In this Perspective, we give an overview of this emerging field by linking history and theoretical predictions to a general ou...
Article
Full-text available
A possible engineering of materials with diverse bio- and nano-applications relies on robust self-assembly of oligonucleotides. Bottom-up approach utilizing guanine-rich DNA oligonucleotides can lead to formation of G-wires, nanostructures consisting of continuous stacks of G-quartets. However, G-wire structure and self-assembly process remain poor...
Article
Alcohol ferrofluids made of ferrimagnetic barium hexaferrite (BHF) nanoplatelets (NPLs) form a unique example of a dipolar fluid – a liquid magnet. Its formation is induced at a high enough concentration of the NPLs. The key interactions between the NPLs are long-ranged dipolar magnetic and screened anisotropic electrostatic. Herein, we report the...
Article
Full-text available
Nematic liquid crystals have been known for more than a century, but it was not until the 60s–70s that, with the development of room temperature nematics, they became widely used in applications. Polar nematic phases have been long-time predicted, but have only been experimentally realized recently. Synthesis of materials with nematic polar orderin...
Article
Full-text available
The recent discovery of the ferroelectric nematic phase has opened the door to experimental investigation of one of the most searched liquid crystal phases in decades, with high expectations for future applications. However, at this moment, there are more questions than answers. In this work, we examine the formation and structure of large polar ne...
Article
Full-text available
Guanine-rich DNA sequences self-assemble into highly stable fourfold structures known as DNA-quadruplexes (or G-quadruplexes). G-quadruplexes have furthermore the tendency to associate into one-dimensional supramolecular aggregates termed G-wires. We studied the formation of G-wires in solutions of the sequences d(G4C2)n with n = 1, 2, and 4. The d...
Poster
Full-text available
Is it our great pleasure to invite you all to participate and submit your contributions to the 18th International Conference on Ferroelectric Liquid Crystals – Polarity and Chirality in Soft Matter, which will be held from 6th to 10th of September 2021 in Ljubljana (Slovenia). You are invited to submit the abstracts via our online submission form...
Preprint
The recent discovery of the ferroelectric splay nematic phase has opened the door to experimental investigation of one of the most searched liquid crystal phases in decades, with high expectations for future applications. However, at this moment, there are more questions than answers. In this work, we examine the formation and structure of large po...
Poster
Full-text available
Dear Friends and Colleagues, Is it our great pleasure to invite you all to participate in the 18th International Conference on Ferroelectric Liquid Crystals – Polarity and Chirality in Soft Matter, which will be held from 6th to 10th of September 2021 in Ljubljana (Slovenia). We are looking forward to welcoming you in Ljubljana. The conference wi...
Preprint
Nematic liquid crystals have been known for more than a century, but it was not until the 60s-70s that, with the development of room temperature nematics, they became widely used in applications. Polar nematic phases have been long-time predicted, but have only been experimentally realized recently. Synthesis of materials with nematic polar orderin...
Article
Full-text available
We present a theoretical analysis of optical diffractive properties of magnetically tunable optical transmission gratings composed of periodically assembled layers of a polymer and a ferromagnetic liquid crystal (LC). The orientational structure of the LC layers as a function of an applied magnetic field is calculated by minimization of the Landau-...
Article
Full-text available
By employing a combination of Molecular Dynamics simulations and experimental SAXS studies, we investigate low-concentration suspensions of polydisperse magnetic platelets with dipole moments perpendicular to the platelets' plane. Exploiting the precise control of platelet size and shape in simulation, we are also able to contrast these results wit...
Article
Ferroelectric ordering in liquids is a fundamental question of physics. Here, we show that ferroelectric ordering of the molecules causes the formation of recently reported splay nematic liquid-crystalline phase. As shown by dielectric spectroscopy, the transition between the uniaxial and the splay nematic phase has the characteristics of a ferroel...
Preprint
Ferroelectric ordering in liquids is a fundamental question of physics. Here, we show that ferroelectric ordering of the molecules causes formation of recently reported splay nematic liquid-crystalline phase. As shown by dielectric spectroscopy, the transition between the uniaxial and the splay nematic phase has the characteristics of a ferroelectr...
Article
A comparative experimental investigation of the dependence of second harmonic generation (SHG) on an applied external voltage between the standard nematic liquid crystalline material and an analogue ferromagnetic nematic liquid crystalline material was performed by using a fundamental optical beam at 800 nm wavelength. For the ferromagnetic materia...
Preprint
A comparative experimental investigation of the dependence of second harmonic generation (SHG) on applied external voltage between the standard nematic liquid crystalline material and an analogue ferromagnetic nematic liquid crystalline material was performed by using a fundamental optical beam at 800 nm wavelength. For a ferromagnetic material, th...
Article
In recent years liquid crystals (LCs) responding to light or electrical fields gained significant importance as multifunctional materials. Here we report on two new series of photoswitchable bent‐core liquid crystals (BCLCs) derived from 4‐cyanoresorcinol as the central core connected to an azobenzene based wing and a phenyl benzoate wing. Series o...
Article
Bent-core liquid crystals (BCLCs) exhibit unique properties like spontaneous breaking of the mirror symmetry and polar switching by electric fields, forming the basis of a range of applications currently being...
Article
Full-text available
Different liquid crystalline phases with long-range orientational but not positional order, so-called nematic phases, are scarce. New nematic phases are rarely discovered, and such an event inevitably generates much interest. Here, we describe a transition from a uniaxial to a novel nematic phase characterized by a periodic splay modulation of the...
Article
Full-text available
The influence of structural constraints on the relaxation dynamics of three polyurea networks with varying degree of crosslinking, has been studied by means of a thorough analysis of broadband dielectric spectroscopy measurements. Two different relaxation processes are observed, namely, a fast process involving the soft poly(propylene oxide) chains...
Article
Successful realization of ferromagnetic nematic liquid crystals has opened up the possibility to experimentally study a completely new set of fundamental physical phenomena. In this contribution we present a detailed investigation of some aspects of the static response and the complex dynamics of ferromagnetic liquid crystals under the application...
Preprint
Different liquid crystalline phases with long-range orientational but not positional order, so-called nematic phases, are scarce. It rarely occurs that a new nematic phase is discovered and such event is inevitably accompanied by a great interest. Here, we describe a transition from uniaxial to novel nematic phase characterized by a periodic splay...
Article
In the present work, a detailed analysis of the glassy behavior and the relaxation dynamics of the liquid crystal dimer α-(4-cyanobiphenyl-4′-yloxy)-ω-(1-pyrenimine-benzylidene-4′-oxy) heptane (CBO7O.Py) throughout both nematic and smectic-A mesophases by means of broadband dielectric spectroscopy has been performed. CBO7O.Py shows three different...
Article
We investigate dynamic magneto-optic effects in a ferromagnetic nematic liquid crystal experimentally and theoretically. Experimentally we measure the magnetization and the phase difference of the transmitted light when an external magnetic field is applied. As a model we study the coupled dynamics of the magnetization, M, and the director field, n...
Article
The pioneering realization of suspensions of ferroelectric nanoparticles in a nematic host was one of excellent contributions of Yuri Reznikov to the science of liquid crystals [Y. Reznikov et al., Appl. Phys. Lett. 82 (2003) 191]. This achievement created great excitement as it entailed the enhancement of materials' dielectric properties and incre...
Article
Magnetic nanoparticles (MNPs) functionalized with (pro)mesogenic ligands are implemented into a nematic liquid crystal (LC) and studied regarding both colloidal stability and magneto-optical behavior. In this study, the particle surface is specifically engineered to tune the MNP interactions with the LC host. For this purpose, four types of (pro)me...
Article
A new bent-core liquid crystalline material consisting of a 4-cyanoresorcinol unit with two terephthalate based rod-like wings and terminated by two short alkyl chains was synthesized. Its liquid crystalline (LC) self-assembly and the development of polar order in the LC phases were investigated. The polar order is characterised using second harmon...
Article
Full-text available
We provide an overview of the effect of the molecular structure on the dielectric properties of dimers exhibiting nematic and twist-bend nematic phases with special focus on how the conformational distribution changes are reflected by the dielectric behaviour. Nematic dimers show distinctive dielectric properties which differ from those of archetyp...
Conference Paper
Full-text available
Mesophase behaviour of dimeric compounds with a flexible spacer and exhibiting a nematic-nematic transition has recently attracted much scientific attention. In particular, the low temperature nematic (Nx) phase with an intricate structure on the nanoscale level has been intensively studied using various experimental techniques. We discuss the stru...
Conference Paper
The development of polar order in the LC phases of achiral bent-core liquid crystals (BCLCs) is of significant interest, 1 though the molecular design principles leading to different modes of polar order are not yet fully understood. In recent years there is a growing interest for photosensitive BCLCs. 2 Lateral fluorine substitution represents one...
Article
We report a comprehensive dielectric characterization of a liquid crystalline binary mixture composed of the symmetric mesogenic dimer CB7CB and the nonsymmetric mesogenic dimer FFO9OCB. In addition to the high-temperature nematic phase, such a binary mixture shows a twist-bend nematic phase at room temperature which readily vitrifies on slow cooli...
Article
We present structural studies of a dimeric compound composed of a central heptyl spacer linking two mesogens consisting of terphenyl units at which two adjacent fluoro groups are attached to each central ring. The terminal rings are linked to pentyl chains as terminal groups. The material exhibits a nematic-nematic transition and a low temperature...
Article
Two isomeric achiral bent-core liquid crystals involving a 4-cyanoresorcinol core and containing a carbosilane unit as nanosegregating segment were synthesized and were shown to form ferroelectric liquid-crystalline phases. Inversion of the direction of one of the COO groups in these molecules leads to a distinct distribution of the electrostatic p...
Article
Full-text available
We report a calorimetric study of a series of mixtures of two twist-bend liquid crystal dimers, the 1’’,7’’-bis(4-cyanobiphenyl)-4’-yl) heptane (CB7CB) and 1´´-(2´,4-difluorobiphenyl-4´-yloxy)-9´´-(4- cyanobiphenyl -4´- yloxy) nonane (FFO9OCB), the molecules of which have different effective molecular curvatures. High-resolution heat capacity measu...
Article
The nature of the nematic-nematic phase transition in the liquid crystal dimer 1 '',9 ''-bis(4-cyanobiphenyl-4'-yl) nonane (CB9CB) has been investigated using techniques of calorimetry, dynamic dielectric response measurements, and H-2 NMR spectroscopy. The experimental results for CB9CB show that, like the shorter homologue CB7CB, the studied mate...
Article
A bent-core mesogen consisting of a 4-cyanoresorcinol unit as the central core and laterally fluorinated azobenzene wings forms four different smectic LC phase structures in the sequence SmA - SmCs -SmCsPAR - M, all involving polar SmCsPS domains with growing coherence length of tilt and polar order on decreasing temperature. The SmA phase is a clu...
Article
This paper describes a detailed study of the nematic (N)-isotropic (I) phase transition in the homologous series of liquid crystal dimers, the α-(4-cyanobiphenyl-4ʹ-oxy)-ω-(1-pyreniminebenzylidene-4ʹ-oxy)alkanes (CBOnO.Py) by means of calorimetric and dielectric measurements as a function of temperature. It is concluded that for this transition, th...
Article
This paper reports a novel liquid crystal phase having characteristics of a twist-bend nematic phase formed by a non-symmetric ether-linked liquid crystal dimer. The dimer 1’’- (2’, 4 – difluorobiphenyl - 4’ - yloxy) - 9’’-(4 - cyanobiphenyl- 4’-yloxy) nonane (FFO9OCB) exhibits two liquid-crystalline phases on cooling at a sufficiently high rate fr...
Article
The synthesis and characterization of three bent-rod dimers are reported. Very long flexible spacers that include methylene units and either a phenyl ring or a triazole moiety as connecting structures join the bent- and rod-promesogenic cores. Polarizing microscopy, modulated differential scanning calorimetry, X-ray diffraction at variable temperat...
Article
The bulk self-assembly of bent-core molecules based on the novel structure 2-methoxy-4,6-bis(1',2',3' triazol- 40-yl)-1,3,5-triazine is reported together with their luminescent and electrochemical properties. Two families of compounds with lateral branches of different lengths have been investigated. Columnar mesomorphism with short stacking distan...
Article
Full-text available
We report an experimental study on confined systems formed by butyloxybenzylidene octylaniline liquid crystal (4O.8) + gamma-alumina nanoparticles. The effects of the confinement in the thermal and dielectric properties of the liquid crystal under different densities of nanoparticles is analyzed by means of high resolution Modulated Differential Sc...
Article
Broadband dielectric spectroscopy (10^3 Hz-1.8x10^9 Hz) has been performed on the odd non-symmetric liquid crystal dimers of the series α - (4 - cyanobiphenyl- 4'- oxy)- ω- (1-pyreniminebenzylidene-4'-oxy) akanes (CBOnO.Py) with n ranging from 3 to 11, as a function of temperature. A previous thermal behaviour study through heat capacity measuremen...
Article
Full-text available
Broadband dielectric spectroscopy spanning frequencies from 10(-2) to 1.9 × 10(9) Hz has been used to study the molecular orientational dynamics of the glass-forming liquid crystal 1",7"-bis (4-cyanobiphenyl-4'-yl)heptane (CB7CB) over a wide temperature range of the twist-bend nematic phase. In such a mesophase two different relaxation processes ha...
Article
We report the synthesis and characterization of main-chain liquid-crystalline polymers via the hydrosilylation polyaddition of a divinyl terminated bent-core mesogenic monomer and tetramethyldisiloxane. Interestingly, these bentcore main-chain polymers form the “dark conglomerate” mesosphase (DC) in broad ranges of temperature. This unique chiral i...
Article
What a core-ker! By the appropriate combination of promesogenic bent-core structures and the C(60)  unit, lamellar polar liquid-crystal phases were induced. The supramolecular organization of the functional fullerene-based assemblies, the temperature range of the soft phase, the stabilization of the mesophase-like order at room temperature, and the...
Article
Full-text available
In this work, a study of the nematic (N)-isotropic (I) phase transition has been made in a series of odd non-symmetric liquid crystal dimers, the alpha-(4-cyanobiphenyl-4'-yloxy)-omega-(1-pyrenimine-benzylidene-4'-oxy) alkanes, by means of accurate calorimetric and dielectric measurements. These materials are potential candidates to present the elu...
Article
Broadband dielectric spectroscopy (10(3) to 1.8 × 10(9) Hz) and specific heat measurements have been performed on the odd nonsymmetric liquid crystal dimer α-(4-cyanobiphenyl-4'-oxy)-ω-(1-pyreniminebenzylidene-4'-oxy)undecane (CBO11O·Py), as a function of temperature. The mesogenic behavior is restricted to a nematic mesophase which can be supercoo...

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Projects (2)
Project
Development of a statistical mechanical picture able to describe the alpha relaxation in polymers, also in the presence of confinement effects. The actual scheme is based on an appropriate thermodynamic potential associated to configurational fluctuations in a supercooled liquid. Recent results relate to the possibility of estimating the cooperativity at Tg from just the relaxation function obtained from either modulated calorimetry or other methods such as mechanical or dielectric spectroscopy. Latest papers: 1) Polym. International 64, 1506 (2015) 2) PRE 91, 052603 (2015) 3) PRE 94, 052504 (2016)