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post-docs

Welcome to Rijeesh and Nikolay.

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Rijeesh Nikolay

Welcome to our new post-doc Rijeesh (left) and phd Nikolay (right) who have joined our team. Rijeesh will be working on making cholesteric LC shells for reflector tags. While Nikolay will aim to generate tube-shaped liquid crystal elastomer actuators for biomedical applications.




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New Paper in Materials by MDPI Journals


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(Click the graphical abstract above to read the article online, it is Open-Access)



Congratulations
to Anshul & Jan on the publication in Materials: “Electrospun Composite Liquid Crystal Elastomer Fibers”!

This is the first study to date that shows and analyzes the irreversible actuation of photo-crosslinkable reactive mesogens single axially electrospun with a carrier polymer, to create liquid crystal elastomer (LCE) fibers. Don't forget to check out the supplementary info for more details!






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New Paper in J. of Molecular Liquids

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(Click the figure image above to access the article online, please email Jan if you cannot download the pdf file)



Congratulations
to JungHyun & Rao on the publication in the Journal of Molecular Liquids titled: “Sub-second dynamic phototuning of alignment in azodendrimer-doped nematic liquid crystal shells”!

For the 1st time(!!), a study documents the photoswitching of azodendrimer in liquid crystal shells produced by microfluidics. Ultimately, our group members & colleagues find that phase separation may occur in shells when the dendrimer is in the trans ground state, and that photo switching turns such shells uniform - further indicating that the cis state is better soluble in the LC.

Hooray for the good start to the 2018 year Laugh




(Fyi - Also, I think this paper is the 1st to show results obtained from our new confocal microscope as well…so HD, so cool)

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New Langmuir Paper Released Online

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(Click the graphical abstract image above to access the article online, please email either Jan or Rao if you cannot download the pdf file)


Congratulations to Larry & Rao on the publication in Langmuir titled: “Microfluidic Tensiometry Technique for the Characterization of the Interfacial Tension between Immiscible Liquids”!

This is Larry's 1st paper in our group (!) and also Rao's 1st time serving as last author on a paper (!)

In this study, Larry and Rao borrow inspiration from the biologists and use the novel technique of micropipette aspiration (commonly used to measure the viscoelastic properties of living cells) to measure the interfacial tension of 5CB, water, and surfactants with a high degree of accuracy (from the sub-millinewton per meter to several hundred millinewton per meter range) solely from experimental observations of the droplet deformation. This is highly unique as information on the liquid density is not needed to find the interfacial tension.




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Christina Schütz joins the team

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We're happy to welcome our new post-doc: Christina Schütz! She officially joined the ESMP team at the start of February, and will mainly be working with Camila on advancing projects related to CNC work. She received her master's from Martin-Luther-University Halle-Wittenberg in Germany (the same place where Jan did his habilitation thesis!), and then her PhD in materials chemistry from Stockholm University. Christina joins us for her 2nd post-doc, after spending a year at Wim Thielemans' lab in KU Leuven, Belgium. Happy to have another chemist joining us!

You can contact Christina via e-mail here.




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Hakam Agha joins the team

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We have the great pleasure of welcoming Dr. Hakam Agha into the ESMP team. He will be working as a post-doc with us and with the LC Nano group of Giusy Scalia for at least six months, hopefully more. He got his Ph.D. in physics from the University of Strasbourg and was most recently working as post-doc with Christian Bahr and Stefan Herminghaus at the Max Planck Institute for Dynamics and Self-Organization in Göttingen. You can contact Hakam via e-mail here.

Welcome!!


Rao and Larry join the group

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On the 14th of October 2015 we had the unusual pleasure to welcome two new group members on the same day, Venkatasubbarao (we call him just 'Rao') Jampani (left) and Larry Honaker (right). Rao is a post-doc working within the INTERACT project, focusing primarily on soft robotics based on liquid crystal elastomers with non-standard morphologies and topologies, and Larry is a Ph.D. candidate, working within his own AFR project LIMEFLOW, which deals with flow of liquid metals, in particular the possibility of achieving liquid metal jets co-flowing within polymer solutions.

Johanna Bruckner joins as post-doc

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We have the fortune to welcome Dr. Johanna Bruckner in our team. Johanna recently defended her Ph.D., carried out under the supervision of Frank Gießelmann, at the University of Stuttgart, and she secured a fellowship from the Dr. Leni Schöninger Stiftung for doing a six-month post-doc with us in Luxembourg. She will be working on liquid crystalline suspensions of cellulose nanocrystals (CNC) in various solvents. In doing so, she will be working closely with our other CNC researchers, in particular Camila, who is the Ph.D. candidate in the MISONANCE project.

Yong Geng joins as post-doc

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It is our great pleasure to welcome Yong Geng to our group as a post-doc. After obtaining his Ph.D. with Prof. Maria Helena Godinho in Lisbon he worked as a post-doc with Prof. Ralf Stannarius and Dr. Alexey Eremin in Magdeburg, before he came to Luxembourg. He will be working on colloidal crystals of cholesteric shells, produced in a microfluidic set-up, focusing on the optical properties and the pattern formation of these systems. This research is the core of the interdisciplinary dual-PI project UNIQUE, funded by University of Luxembourg. The second partner of the project is the team around Gabriele Lenzini and Peter Ryan at the UL's Interdisciplinary Center for Security and Trust, which will analyze the patterns generated by the colloids from an information content point of view. Young will thus interact closely with Samir Ouchani, a post-doc in computer science working under the guidance of Gabriele.

Martin Urbanski joins the group

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We have the pleasure of welcoming Dr. Martin Urbanski to the Experimental Soft Matter Physics group as a post-doc. He comes from the University of Paderborn, Germany, where he worked with Prof. Heinz Kitzerow. Martin secured a personal post-doc grant from the Fonds National de la Recherche Luxembourg (FNR) for a two-year project entitled DISGONA. He will be studying nematic liquid crystals functionalized with gold nanoparticles by means of dielectric spectroscopy.

New paper in Advanced Optical Materials

Geng et al 2017 inside cover
**Update (12.01.17 - POM images fromYong's paper are selected for the inside cover of Advanced Optical Materials! Click the cover above to freely access the article online)

Congratulations to Yong on the publication in Adv. Opt. Mater. titled: “Through the Spherical Looking-Glass: Asymmetry Enables Multicolored Internal Reflection in Cholesteric Liquid Crystal Shells”!

Spheres of cholesteric liquid crystal generate dynamic patterns due to selective reflection from a helical structure subject to continuously curved boundaries. In this paper the patterns are investigated exclusively.

Click here for an extended layman's abstract summary written by Jan & some info about the curious Alice in Wonderland-like title Happy



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New paper on organic functionalized nanoparticles in nematic LCs


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(click the above image to access the article online)


Congratulations to Martin on the publication in J. Mater. Chem. C of his dielectric spectroscopy study “Why organically functionalized nanoparticles increase the electrical conductivity of nematic liquid crystal dispersions”!

This paper gives a first systematic study of how and why nanoparticle doping raises the electrical conductivity of thermotropic liquid crystals like the commonly studied 5CB. By a careful analysis of the dielectric spectra, he shows that the hydrodynamic radius of the ionic charge carrier is much smaller than the nanoparticles, ruling out the particles themselves as the source of conductivity. The ligand molecules are also not the reason, as is demonstrated by strong sonication of the dispersions, such that the ligands detached from the nanoparticles. While this causes nanoparticle aggregation and the loss of suspension stability, the effect on conductivity is negligible. The ligand shell is, however, partially responsible, because the ions giving rise to the conductivity increase are most likely remnants from the ligand-functionalized nanoparticle synthesis process. We propose that these ions are brought in with the ligand shell when the particles are dispersed in the 5CB. Interestingly, the ions appear not to be released in an isotropic and aromatic solvent such as toluene, which is often the host for commercial gold nanoparticle suspensions, but 5CB is an ideal host for their dissolution. The aliphatic ligand shell has a higher compatibility with 5CB than with toluene, thanks to the alkyl tail of 5CB, and at the same time the high polarity of the 5CB (due to the cyano group) allows better ion dissolution than in regular hexane. Finally, the nematic order of the 5CB solvent provides an anisotropic environment in which the ligands are stretched out preferentially along the director, making release of ligand-bound ions to the solvent more likely. 



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New paper on the details of cholesteric LC shell reflection patterns

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(click the above image to access the article online)

Our fruitful collaboration with Irena Drevensek-Olenik (Ljubljana) and Romano Rupp (Vienna) has resulted in a new article published in Liquid Crystals (special “John Goodby Festschrift” issue). It's also open access!

The paper is entitled “Elucidating the fine details of cholesteric liquid crystal shell reflection patterns” and it combines optical analysis and computer simulations with experimental investigations in the polarizing microscope, allowing a much advanced understanding of the intricate communication patterns arising in collections of short-pitch cholesteric liquid crystal shells, produced using microfluidic techniques. We can now give quantitative information on how the size of the main reflection spot scales with shell size and we explain a number of reflection spots that have previously been ignored. We show that one must consider a certain variation of incidence and reflection angles as well as reflection within the liquid crystal shell in order to explain the patterns. A particularly interesting result is the demonstration and explanation of the first reflection spots that involve communication between three shells: light incident close to the perimeter of one shell can be reflected to an adjacent shell at such an angle that the reflected beam hits a third shell, which then in turn reflects it back to the observer.  



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New Post-Doc! Manos Anyfantakis joins the team

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We're happy to welcome our new post-doc: Manos Anyfantakis! He officially joined the ESMP team at the start of July, and will mainly be working on advancing projects related to hydrodynamic flows, kinetic arrest, LC structure formation in the CNC work we have happening. He received his masters applied molecular spectroscopy in 2007, earned a phd in chemistry in Greece in 2010, and has since travelled to Germany and France for postdocs on the wetting of surfactant solutions and optofluidics phenomena before finally joining us in Luxembourg. You can contact Manos via e-mail here.





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Ross Volpe visits the ESMP group

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We have the pleasure to be hosting Ross Volpe, Ph.D. candidate, from Prof. Christopher Yakacki's group at the University of Denver, Colorado, USA, until August (the longest we've had a guest over yet!).
During his stay, he will mostly work with Rao on further advancing the actuation of micro shells & also start the development on actuating cylinders. We hope that these months will result in a great collaboration!



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