A5029196867- Liquid Crystal Research Advancements
- Photonic Crystals and Applications
- Advanced Materials and Mechanics
- Nonlinear Dynamics and Pattern Formation
- Material Dynamics and Properties
- Molecular spectroscopy and chirality
- Solid-state spectroscopy and crystallography
- Plant Reproductive Biology
- Advanced NMR Techniques and Applications
- Surfactants and Colloidal Systems
- Theoretical and Computational Physics
- Spectroscopy and Quantum Chemical Studies
- Orbital Angular Momentum in Optics
- Pickering emulsions and particle stabilization
- Plant and animal studies
- Mechanical and Optical Resonators
- Photonic and Optical Devices
- Acoustic Wave Resonator Technologies
- NMR spectroscopy and applications
- Quantum Electrodynamics and Casimir Effect
- Advanced Sensor and Energy Harvesting Materials
- Force Microscopy Techniques and Applications
- Optical Polarization and Ellipsometry
- Nonlinear Optical Materials Research
- Micro and Nano Robotics
Jožef Stefan Institute
2014-2024
University of Ljubljana
2014-2024
University of Southern Denmark
2024
University of Trento
2024
Centre of Excellence NAMASTE
2010-2014
National Institute of Advanced Industrial Science and Technology
2014
Tehnološko raziskovalni center JUB
2008
Institute of Mathematics, Physics, and Mechanics
2002-2006
Institute of Physics
1999
Brown University
1999
The light scattering and electro-optic response of new material with display potential are investigated. materials consist microdroplets nematic liquid crystals which spontaneously formed in a solid polymer at the time its polymerization. Droplet size, spacing, distribution readily controlled these to allow optimization displays based upon electrically from crystal droplets. Preliminary experimental theoretical studies properties show offer features suitable for many applications.
The ability to generate regular spatial arrangements of particles is an important technological and fundamental aspect colloidal science. We showed that confined a few-micrometer-thick layer nematic liquid crystal form two-dimensional structures are bound by topological defects. Two basic crystalline were observed, depending on the ordering around particle. Colloids inducing quadrupolar order crystallize into weakly ordered structure, where particle interaction mediated sharing localized...
Tying knots and linking microscopic loops of polymers, macromolecules, or defect lines in complex materials is a challenging task for material scientists. We demonstrate the knotting topological chiral nematic liquid crystal colloids into links arbitrary complexity by using laser tweezers as micromanipulation tool. All with up to six crossings, including Hopf link, Star David Borromean rings are demonstrated, stabilizing colloidal particles an unusual soft matter. The classified quantized...
Abstract Phenomenological Landau–de Gennes modelling based on the free energy of nematic liquid crystal colloids is reviewed. Nematic phase, gradient order, and surface anchoring contributions to total are used. The numerical finite difference relaxation technique explained as an efficient tool for minimisation energy. Effects mesh allocation discussed. Various conceptually different colloidal structures calculated show universality model. Single particles, dipolar–quadrupolar dimers,...
The last years have witnessed remarkable advances in our understanding of the emergence and consequences topological constraints biological soft matter. Examples are abundant relation to (bio)polymeric systems range from characterization knots single polymers proteins that whole chromosomes polymer melts. At same time, considerable been made description interplay between physical properties complex fluids, with development techniques now allow researchers control formation interaction...
The scattering matrix, differential cross section, and the total section for a small nematic droplet are derived in Rayleigh-Gans approximation. Different director configurations considered droplet. Those studied which result spherical from different molecular anchoring angles at wall. Configurations both absence presence of an applied field their properties examined. Some simple cases treated detail results presented closed form. In other more practical numerical section. Strong...
Computer simulations are made of polarizing microscope textures supramicron-sized nematic droplets with director configurations which commonly occur in polymer and other dispersions. The computed from polarization rotations phase shifts caused by nonuniform optical anisotropies the structure liquid crystal droplets. treatment is limited to case spherical optically soft so that reflection refraction at droplet surface, as well on any internal structure, can be neglected. Simulated four...
Magnetic resonance and calorimetric studies of 4'-n-pentyl-4-cyanobiphenyl confined to Vycor glass, a random network pores with average diameter \ensuremath{\sim}70 \AA{}, are reported. Under such severely constrained ocnditions, the nematic-to-isotropic transition is replaced by continuous evolution orientational order in pores. Our findings explained Landau type model where liquid crystal independent pore segments, suggesting that glassylike large extend locally determined.
Applications for photonic crystals and metamaterials put stringent requirements on the characteristics of advanced optical materials, demanding tunability, high Q factors, applicability in visible range, large-scale self-assembly. Exploiting interplay between structural properties, colloidal lattices embedded liquid (LCs) are promising candidates such materials. Recently, stable two-dimensional configurations were demonstrated nematic LCs. However, question as to whether 3D structures can...
The scattering matrix, differential cross section, and total section for supramicrometer-size nematic droplets in a polymeric matrix are derived the anomalous-diffraction approach. Scattering patterns calculated detail three different nematic-director configurations: one characteristic of droplet strong external field, other outside field case normal surface anchoring, third an isotropic with surface-induced layer. results, which presented graphically, indicate dependence diffraction on...
It has been predicted, but never confirmed, that colloidal particles in a nematic liquid crystal could be self-assembled by delocalized topological defects and entangled disclinations. We show experimentally theoretically dimers 1D structures bound defect loops can indeed created locally thermally quenching thin layer of the around selected particles. The entanglement provides strong stringlike binding, which is ten thousand times stronger compared to water-based colloids. This unique...
The director-field configuration of a nematic liquid crystal confined to spherical cavity within urethane polymer is observed transform from radial- axial-type structure as the radius cavity, temperature, or strength an applied electric field are varied. phase diagram, anchoring at droplet wall, and value reduced inside determined for different polymer/liquid interfaces.
Deuterium NMR of nematic droplets in a polymer matrix reveals the effect confinement on molecular orientational ordering near nematic-isotropic ($N\ensuremath{-}I$) phase transition. For large 0.35 \ensuremath{\mu}m diameter, $N\ensuremath{-}I$ transition is first order. less than 0.035 isotropic shows paranematic order and replaced by continual evolvement from to This result provides demonstration Sheng's prediction that coexistence curve terminates at critical enclosure size.
Frustration of chiral ordering is explored in cholesteric liquid crystal droplets with planar degenerate anchoring using numerical modeling. Droplets variable pitches are studied, demonstrating the role a gradually increasing pitch and corresponding equilibrium structures. All previously known structures identified but notable differences. The presented director fields complemented detailed description defect regions. characteristic half-diameter +2 disclination from previous studies found...
We present experimental and theoretical study of colloidal interactions in quadrupolar nematic liquid crystal colloids, confined to a thin planar cell. Using the laser tweezers, particles have been positioned vicinity other their determined using particle tracking video microscopy. Several types analyzed: (i) pair interaction, (ii) interaction an isolated quadrupole with chain, (iii) two-dimensional (2D) crystallite. In all cases, are order several 100k(B)T for 2 microm particles, which...
Abstract Monomers with reactive double bonds were mixed liquid crystals and polymerized under UV irradiation. The polymer networks formed are anisotropic consist of fibrils. orientation the depend on during polymerization. Optical scanning electron microscopy (SEM) used to study networks.
Deuterium magnetic resonance of cylindrically confined liquid crystals reveal a structural transition driven by homeotropic-to-planar anchoring in the nematic phase and an orientational wetting (quasicomplete-to-partial) isotropic as molecular length surface coupling agent is decreased. A simple phenomenological description reveals weak positive order parameter homeotropic case negative one planar case. The absence symmetry breaking attributed to interfacial coupling.
Possible phases in a nematic liquid crystal confined to spherical submicrometer droplet embedded solid polymer are analyzed terms of Landau--de Gennes theory. For with radial structure we show that the strength nematic-polymer interfacial interaction affects nematic-paranematic (partially ordered isotropic phase) phase transition and may addition induce boundary-layer phase. This boundary layer exists only narrow (\ensuremath{\sim}0.1 K) temperature interval above for restricted range...