Experimental Soft Matter Physics

JungHyun's article makes the cover page on Soft Matter

Just in time for Christmas, JungHyun's beautiful collection of liquid crystal shells got to decorate the cover of issue 2 of volume 12 of Soft Matter. Her article "Influence of interface stabilisers and surrounding aqueous phases on nematic liquid crystal shells", written together with Kevin and Jan, appears on page 367 of this issue. Congratulations on your second journal cover, JungHyun!

Jan's inaugural lecture 10th of December 2015

With a slight delay, it is finally time on Thursday 10th of December for Jan to give his inaugural lecture at University of Luxembourg, entitled Contrasts drive self-assembly and beauty is born. This is a popular scientific lecture open to the public, and it will span a broad spectrum, from giving some fascinating glimpses of the research we do in the group to discussing the benefits of cross-fertilizing fundamental and applied research, taking an open-minded and interdisciplinary attitude.

The lecture will take place in Salle Tavernas, Campus Limpertsberg (the old monastery on 102 Avenue Pasteur) at 18:00. You are most welcome!

ESMP group at the Luxembourg Science Festival

The Experimental Soft Matter Physics group will participate in the Luxembourg Science Festival, during the sessions for school classes on Thursday 12th and Friday 13th of November. We will exhibit a show on polarized light and birefringence, and how observation between crossed polarizers can be used to reveal information about materials that is hidden to the naked eye, like where stresses build up and whether or not an anisotropic order exists on macroscopic scale.

We will be in the "Tente parvis", at workshop 38: "Lumière fantastique!".

Paper on the complex influence of the surrounding phases on liquid crystal shells accepted

Congratulations to JungHyun and Kevin! During Kevin's bachelor thesis work (supervised by JungHyun) they discovered a very surprising textural change during the nematic-isotropic transition of liquid crystal shells. This became the start of a detailed investigation of what the substances that surround liquid crystal shells, typically surfactants and random coil polymers dissolved in aqueous mixtures, actually do to the liquid crystal. Now this study has been accepted for publication as a Communication in Soft Matter. You can download the 'just accepted' version here, and you will then see that water actually enters the liquid crystal, affecting its clearing point, and surfactant can go through from one side to the other, turning a hybrid shell uniformly homeotropic after some time. On the other hand, if the surfactant concentration is too low, the alignment is planar, because then the planar-aligning influence of water dominates. Polymers like PVA just stabilize the shells, they don't affect the alignment.

Nina joins the group

We have a new student researcher: Nina Schwarz. Nina is a 3:rd semester bachelor student in physics at the University of Luxembourg, and since the 15th of October 2015 she will be working 10 hours per week in our labs to help with various tasks, and hopefully learn something and have some fun in the process. Currently she focuses on assisting Camila with synthesis of cellulose nanocrystals.

Rao and Larry join the group

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.

Vanessa joins the group

We have the pleasure to welcome Vanessa Schmidt-Barbé as new secretary at our Research Unit, working primarily within Jan's ERC project INTERACT.

Paper on dual-core liquid crystal electrospinning

Congratulations to YooMee, whose M.Sc. research on the preparation of multiresponsive fibers, by electrospinning dual-core fibers with different liquid crystals next to each other, is now on-line at Journal of Materials Chemistry C. The paper, published in collaboration with Prof. Changsoon Kim at Seoul National University, describes the possibilities opened by incorporating multiple liquid crystals in one and the same fiber, giving a single fiber multiple functions (like selective reflection and birefringence, as in the bottom right pane of the ToC graphic, reproduced here). Apart from the feat of producing the fibers, YooMee gives two messages of great practical importance concerning liquid crystal electrospinning. First, she confirms the recent observation in a paper with DaeKyom as lead author, that electrospun core-sheath fibers must not be collected on hydrophilic substrates like ordinary glass or silicon chips, because then capillary forces from condensed water will deform the fibers. In YooMee's case, she found that the phenomenon even leads to mixing of the adjacent cores. Second, while ionic surfactants are a useful additive to the polymer solution in solid fiber spinning, since they increase the conductivity and reduce the surface tension, they are a bad choice when the fiber contains a liquid crystal core. YooMee found dramatic reductions in clearing point of the encapsulated liquid crystal whenever the polymer sheath solution contained surfactant, indicating that the surfactant actually enters the liquid crystal and disturbs its order. Download her paper at Journal of Materials Chemistry C!

Johanna Bruckner joins as post-doc

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

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.

New article on self-assembled nanowires from discotic liquid crystals

Our collaborator Giusy Scalia and her student Ji Hyun Park just published a beautiful study in Langmuir of studies by AFM and electrical conductivity on nanowires formed by spin coating solutions of discotic liquid crystals. Jan is a co-author because of his contributions in the analysis of the data. It turns out that the choice of solvent is critical for the structure formation, aromatic solvents like toluene and benzene leading to extraordinary long-range order, whereas films produced from solutions in chloroform or alkanes exhibited a very grainy and disordered morphology. Read the paper here.

Meeting in Seoul with Younghui Kim and Mathew Schwartz

In connection to Jan's trip to Korea for YooMee's defense, he took the opportunity to visit wearable technology artist Younghui Kim (Hongik University) and robotics artist/designer Mathew Schwartz (Advanced Institute of Convergence Technologies) to discuss their collaboration within the framework of Jan's ERC project INTERACT. Here the three are gathered in Younghui's fantastic studio in Seoul, surrounded by her artwork.

Visitors from the USA

Also this summer we have the pleasure to host three students from the USA, within the framework of an NSF-funded IRES program devoted to liquid crystal fibers and filaments, headed by Prof. Tony Jakli at Kent State University (co-PIs are Prof. Margaret Frey, Cornell, and Prof. John West, Kent State University). This year our visitors are Emily Kerr, Aditi Naik and Vanessa Sanchez. Here you see them enjoying Luxembourgish Flammkuchen together with Jan and Catherine (who is the local group member working the most with them during their stay).

YooMee defends her M.Sc. thesis

Congratulations to YooMee Kye on her successful defense of her M.Sc. thesis entitled "Multi-core liquid crystal-polymer composite fibers produced by electrospinning" at the GSCST, Suwon, Korea, on the 12th of June 2015. Her work (the key results of which we hope will soon appear also as a journal article) is the first study of electrospinning fibers with more than one liquid crystal core, importantly with each core containing a different liquid crystal. This gives one and the same fiber multiple functionalities and the ability to respond to different stimuli. Below you see us enjoying an excellent Korean dinner as we celebrated the defense in the evening.

New article on cellulose nanocrystals

Christina_CNC-Langmuir-2015A new result from our fruitful collaboration with Stockholm University on cellulose nanocrystal suspensions appeared as an ASAP article in Langmuir today. It contains the best measurements of helix pitch in equilibrium cholesteric suspensions to date, based on a combination of x-ray and optical diffraction measurements. You can find the paper here.

Mathew Schwartz visits us

MatSpeaksOur collaborator at the Advanced Institutes of Convergence Technology (Suwon, Korea), Mathew Schwartz, visits the ESMP group in the beginning of May, giving a talk entitled "Research problem finding and solving through Art and Design". In connection to this visit we had intense discussion around our work on soft robotics within the project INTERACT.

Camila Honorato joins as doctoral candidate

We welcome Camila Honorato as a member of our group! She will be working as a doctoral candidate in the MISONANCE project, carried out in collaboration with the team of Prof. Tanja Schilling at PhyMS, UL. Camila will study the self-assembly of water-suspended cellulose nanocrystals into lyotropic liquid crystal phases, and how this self-assembly competes with the tendency of electrostatically charged nanorod suspensions to arrest into a jammed state. She will interact closely with Anja Kuhnold from Prof. Schilling's group, who is doing theory and computer modeling corresponding to Camila's experiments.

Jan is awarded an ERC Consolidator Grant

On the 12th of March 2015 the European Research Council (ERC) publicized the list of this year's Consolidator Grant winners, making it official that Jan's proposal INTERACT was selected for support. The support means that for the next five years the Experimental Soft Matter Physics group will be working very actively on wearable technology, soft robotics and innovative techniques for secure authentication. As the project gets going (current projected starting date is 1st of April 2015) there will be many updates.

Halle group reunion

In connection to the German Liquid Crystal Conference in Stuttgart we took the opportunity to organize a reunion of the Halle group, with Giusy and JungHyun as "honorary guests". From left to right: Eva (now in Stuttgart), Giusy, Jan, Martin (now in Würzburg), Stefan (now in Leipzig), Sarah (now in Magdeburg) and JungHyun. Hsin-Ling should have been there as well but a train accident in London prevented her from catching her flight, so in the end she could only join us via Skype.

JungHyun and Martin give talks at the German Liquid Crystal Conference

At the 42nd German Liquid Crystal Conference in Stuttgart, JungHyun gave a talk on her and Kevin's work on liquid crystal shells. The talk was entitled "A sensitive interplay between phase transitions and director field reorientations in liquid crystalline shells". Immediately after JungHyun, Martin took the stage and told about his recent work in Paderborn prior to joining the ESMP group, in a talk entitled "Studies on the compatibility of spherical nanoparticles in a nematic host and their impact on the electro-optic properties".

Martin Urbanski joins the group

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.

Benjamin Henx joins the group

Benjamin Henx, bachelor student in the University of Luxembourg physics program, will do his thesis work together with JungHyun during the 2015 spring semester. He will be working on microfluidics, liquid crystals and polymerization.

Sammy Wagner joins the group

Sammy Wagner, student in the University of Luxembourg Master program for physics, will carry out his Master thesis work in the Experimental Soft Matter Physics group. He will be working with suspensions of cellulose nanocrystals, studying liquid crystal and glass formation in connection to our project on the topic, MISONANCE.

Jan's talk at the SPIE SF conference 2015 on-line

On Tuesday 10th of February 2015, Jan gave an invited talk entitled “Dynamic and complex optical patterns from colloids of cholesteric liquid crystal droplets” at the SPIE meeting in San Francisco, in the session “Emerging Liquid Crystal Technologies X”. You can watch the screen recording of the talk (you see the slides and hear the voice) here.

Kick-off for new project MISONANCE

Today is the start of the project MISONANCE, a joint research thrust with the Theory of Soft Condensed Matter Physics group, lead by Tanja Schilling, funded within the CORE scheme of the Fonds National de la Recherche Luxembourg (FNR). The project deals with the balance between liquid crystalline self-assembly and glass formation in suspensions of cellulose nanocrystals, and the preparation of photonic crystal films based on this new bionanomaterial. The project is Jan's first large-scale project on cellulose and it will continue the excellent collaboration with the group of Prof. Lennart Bergström at Stockholm University (non-contracting partner). The theme of MISONANCE is largely the issues discussed in our review article published in NPG Asia Materials last year (the picture is from this open-access paper, which you can download free of charge and without subscription here).

Catherine Reyes joins the group

It is with great pleasure that we welcome our new Ph.D. candidate, Catherine Reyes, coming from Cornell University where she carried out her Master studies with Prof. Margaret Frey. Catherine should have arrived already in September but the paper work for allowing a US citizen and Cornell graduate to start as Ph.D. candidate in Luxembourg turned out to be beyond our wildest imagination… Anyway, she is finally here and she will be working full time on liquid crystal-funcationalized electrospun fibers for wearable technology.