Institute for Complex Molecular Systems

Eindhoven, Netherlands

Institute for Complex Molecular Systems

Eindhoven, Netherlands
Time filter
Source Type

Liu D.,TU Eindhoven | Liu L.,Zernike Institute for Advanced Materials | Onck P.R.,Zernike Institute for Advanced Materials | Broer D.J.,TU Eindhoven | And 2 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

In this work we propose randomly ordered polydomain nematic liquid crystal polymer networks to reversibly generate notable jagged relief patterns at a polymer coating surface by light illumination. The domain size is controlled by the addition of traces of partly insoluble fluorinated acrylate. The photoresponse of the coating is induced by a small amount of copolymerized azobenzene monomers. Upon exposure to UV light, azobenzene undergoes trans to cis isomerization, resulting in a change in molecular order and packing within each domain. The extent of this effect and its directionality depends on the domain orientation. Localized to domain level, this morphological change forms large 3D spikes at the surface with a modulation amplitude of more than 20% of the initial thickness. The process is reversible; the surface topographical patterns erase within 10 s by stopping the light exposure. A finite element model is applied to simulate the surface topography changes of the polydomain coating. The simulations describe the formation of the topographic features in terms of light absorption and isomerization process as a function of the director orientation. The random director distribution leads to surface structures which were found to be in close agreement with the ones measured by interference microscopy. The effect of domain size on surface roughness and depth modulation was explored and related to the internal mechanical constraints. The use of nematic liquid crystal polydomains confined in a polymer network largely simplifies the fabrication of smart coatings with a prominent triggered topographic response.

Filot I.A.W.,Institute for Complex Molecular Systems | Filot I.A.W.,Schuit Institute of Catalysis | Palmans A.R.A.,Institute for Complex Molecular Systems | Palmans A.R.A.,Laboratory of Macromolecular and Organic Chemistry | And 8 more authors.
Journal of Physical Chemistry B | Year: 2010

Understanding the molecular mechanism of cooperative self-assembly is a key component in the design of self-assembled supramolecular architectures across multiple length scales with defined function and composition. In this work, we use density functional theory to rationalize the experimentally observed cooperative growth of C3-symmetrical trialkylbenzene-1,3,5- tricarboxamide-(BTA-) based supramolecular polymers that selfassemble into ordered one-dimensional supramolecular structures through hydrogen bonding. Our analysis shows that the cooperative growth of these structures is caused by electrostatic interactions and nonadditive effects brought about by redistribution of the electron density with aggregate length. © 2010 American Chemical Societ.

News Article | December 13, 2016

The Graduate School of Excellence "Materials Science in Mainz" (MAINZ) has again awarded visiting professorships to two outstanding scientists. The MAINZ Visiting Professorships 2016 were presented at a gala event on Monday evening to Professor Egbert Willem Meijer, a chemist of Eindhoven Technical University in the Netherlands and to Dr. Gen Tatara, a theoretical physicist of the Japanese research institute RIKEN. Visiting professorships are a way to attract foreign scientists to the various departments of the MAINZ Graduate School so they can do part of their research here as well as work with the doctoral candidates studying at MAINZ. Their input can take the form of lectures, seminars, and workshops that help in training doctoral candidates at MAINZ. The visiting professorships have been awarded annually since 2013 to a maximum of two scientists. Egbert Willem Meijer is one of the world's leading scientists in the field of supramolecular chemistry. His research on functional supramolecular polymers has even resulted in a new class of materials. His work on supramolecular polymers, i.e., supra-structures consisting of self-organizing molecules, has also made them interesting from a technological viewpoint, all the more so since Meijer successfully achieved unanticipated material properties. Meijer is Scientific Director of the Institute for Complex Molecular Systems at Eindhoven Technical University. He has received numerous awards and visiting professorships for his work, among them the 2001 Spinoza Award, the highest scientific award in the Netherlands. Besides intensifying scientific collaborations, the chemist will offer MAINZ doctoral candidates an opportunity to participate in a master class in supramolecular chemistry. Dr. Gen Tatara heads a department for theoretical physics at the RIKEN research institute in Japan. He works in spin physics, a field of research with a focus on the intrinsic angular momentum of electrons. Tatara's particular emphasis is on the reciprocal effect between spin currents and magnetization in condensed matter. He has made pivotal contributions to the theoretical description of the dynamics of domain walls. As a visiting professor in Mainz, he will not only forge contacts with scientists in the field of theoretical physics, but also intensify his connections to experimental groups with whom he has in part already published. In particular, the Japanese scientist will offer doctoral candidates at the MAINZ Graduate School an opportunity to participate in courses on theoretical methods in spintronics. The Mainz Graduate School of Excellence was approved through the Excellence Initiative of the German Federal and State Governments in 2007 and its funding was extended for another five years in 2012. It consists of work groups from Johannes Gutenberg University Mainz, TU Kaiserslautern, and the Max Planck Institute for Polymer Research. Doctoral candidates benefit from the outstanding educational opportunities in the field of material sciences. (fltr) Professor Paul Blom from the Max Planck Institute for Polymer Research, Professor Egbert Willem Meijer, 2016 MAINZ Visiting Professor, and Professor Mathias Kläui, Director of the MAINZ Graduate School of Excellence (fltr) Professor Mathias Kläui, Director of the MAINZ Graduate School of Excellence, and 2016 MAINZ Visiting Professor Dr. Gen Tatara

Smulders M.M.J.,Institute for Complex Molecular Systems | Filot I.A.W.,Institute for Complex Molecular Systems | Leenders J.M.A.,Institute for Complex Molecular Systems | Van Der Schoot P.,TU Eindhoven | And 3 more authors.
Journal of the American Chemical Society | Year: 2010

Here, we report on the strong amplification of chirality observed in supramolecular polymers consisting of benzene-1,3,5-tricarboxamide monomers and study the chiral amplification phenomena as a function of temperature. To quantify the two chiral amplification phenomena, i.e., the sergeants-and- soldiers principle and the majority-rules principle, we adapted the previously reported sergeants-and-soldiers model, which allowed us to describe both amplification phenomena in terms of two energy penalties: the helix reversal penalty and the mismatch penalty. The former was ascribed to the formation of intermolecular hydrogen bonds and was the larger of the two. The latter was related to steric interactions in the alkyl side chains due to the stereogenic center. With increasing temperature, the helix reversal penalty was little affected and remained rather constant, showing that the intermolecular hydrogen bonds remain intact and are directing the helicity in the stack. The mismatch penalty, however, was found to decrease when the temperature was increased, which resulted in opposite effects on the degree of chiral amplification when comparing the sergeants-and-soldiers and the majority-rules phenomena. While for the former a reduction in mismatch penalty resulted in a decrease in degree of chiral amplification, for the latter it resulted in a stronger chiral amplification effect. By combining the sergeants-and-soldiers and majority-rules phenomena in a diluted majority-rules experiment, we could further determine the effect of temperature on the degree of chiral amplification. Extending the experiments to different concentrations revealed that the relative temperature, i.e., the temperature relative to the critical temperature of elongation, controls the degree of chiral amplification. On the basis of these results, it was possible to generate a general "master curve" independent of concentration to describe the temperature-dependent majority-rules principle. As a result, unprecedented expressions of amplification of chirality are recorded. © 2010 American Chemical Society.

Zhang X.-Q.,TU Eindhoven | Van Santen R.A.,TU Eindhoven | Van Santen R.A.,Institute for Complex Molecular Systems | Jansen A.P.J.,TU Eindhoven
Physical Chemistry Chemical Physics | Year: 2012

We present a lattice-gas kinetic Monte Carlo model to investigate the formation of silicate oligomers, their aggregation and the subsequent gelation process. In the early oligomerization stage, the 3-rings are metastable, 5-rings and 6-rings are formed in very small quantities, 4-rings are abundant species, linear and branched species are transformed into more compact structures. Results reveal that the gelation proceeds from 4-ring containing species. A significant amount of 5-rings and 6-rings, sharing Si with 4-ring, form in the aging stage. These reveal the formation mechanism of silicate rings and clusters during zeolite synthesis. This journal is © 2012 the Owner Societies.

Ballotta V.,TU Eindhoven | Driessen-Mol A.,TU Eindhoven | Bouten C.V.C.,TU Eindhoven | Bouten C.V.C.,Institute for Complex Molecular Systems | And 2 more authors.
Biomaterials | Year: 2014

Implanted synthetic substrates for the regeneration of cardiovascular tissues are exposed to mechanical forces that induce local deformation. Circulating inflammatory cells, actively participating in the healing process, will be subjected to strain once recruited. We investigated the effect of deformation on human peripheral blood mononuclear cells (hPBMCs) adherent onto a scaffold, with respect to macrophage polarization towards an inflammatory (M1) and reparative (M2) phenotype and to early tissue formation. HPBMCs were seeded onto poly-ε-caprolactone bisurea strips and subjected to 0%, 7% and 12% cyclic strain for up to one week. After 1 day, cells subjected to 7% deformation showed upregulated expression of pro and anti-inflammatory chemokines, such as MCP-1 and IL10. Immunostaining revealed presence of inflammatory macrophages in all groups, while immunoregulatory macrophages were detected mainly in the 0 and 7% groups and increased significantly over time. Biochemical assays indicated deposition of sulphated glycosaminoglycans and collagen after 7 days in both strained and unstrained samples. These results suggest that 7% cyclic strain applied to hPBMCs adherent on a scaffold modulates their polarization towards reparative macrophages and allows for early synthesis of extracellular matrix components, required to promote further cell adhesion and proliferation and to bind immunoregulatory cytokines. © 2014 Elsevier Ltd.

Schaefer C.,Institute for Complex Molecular Systems | Voets I.K.,Institute for Complex Molecular Systems | Palmans A.R.A.,Institute for Complex Molecular Systems | Meijer E.W.,Institute for Complex Molecular Systems | And 4 more authors.
ACS Macro Letters | Year: 2012

In a combined experimental and theoretical approach, we investigate the supramolecular polymerization of ionic discotic amphiphiles into nanorods of varying mean length, depending on the temperature and ionic strength of the buffered aqueous solution. Invoking a nucleated supramolecular polymerization model that explicitly deals with the effects of screened Coulomb interactions, we correlate the degree of cooperativity of the supramolecular polymerization with the ionic strength of the solution, as probed by means of circular dichroism spectroscopy. Experiment and theory show that electrostatic interactions between the amphiphiles in the rods make the polymerization less cooperative, implying that the larger the concentration of mobile ions in the solution the larger the cooperativity due to their screening effect. We furthermore extract quantitative information about the effective surface charge densities of the supramolecular nanorods in solution, a parameter that has been particularly difficult to determine experimentally in other related self-assembled systems. © 2012 American Chemical Society.

Van Der Graaff W.N.P.,TU Eindhoven | Li G.,TU Eindhoven | Mezari B.,TU Eindhoven | Pidko E.A.,TU Eindhoven | And 2 more authors.
ChemCatChem | Year: 2015

Sn-Beta zeolite was prepared by acid dealumination of Beta zeolite, followed by dehydration and impregnation with anhydrous SnCl4. The formation of extraframework Sn (EFSn) species was prevented by the removal of unreacted SnCl4 in a methanol washing step prior to calcination. The resulting Sn-Beta zeolites were characterized by X-ray diffraction, Ar physisorption, NMR, UV/Vis, and FTIR spectroscopy. These well-defined Lewis acid zeolites exhibit good catalytic activity and selectivity in the conversion of 1,3-dihydroxyacetone to methyl lactate. Their performance is similar to a reference Sn-Beta zeolite prepared by hydrothermal synthesis. Sn-BEA zeolites that contain EFSn species exhibit lower catalytic activity; the EFSn species also catalyze formation of byproducts. DFT calculations show that partially hydrolyzed framework Sn-OH species (open sites), rather than the tetrahedral framework Sn sites (closed sites), are the most likely candidate active sites for methyl lactate formation. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Bakker M.H.,Institute for Complex Molecular Systems | Lee C.C.,Novartis | Meijer E.W.,Institute for Complex Molecular Systems | Meijer E.W.,TU Eindhoven | And 3 more authors.
ACS Nano | Year: 2016

Supramolecular polymers are an emerging family of nanosized structures with potential use in materials chemistry and medicine. Surprisingly, application of supramolecular polymers in the field of drug delivery has received only limited attention. Here, we explore the potential of PEGylated 1,3,5-benzenetricarboxamide (BTA) supramolecular polymers for intracellular delivery. Exploiting the unique modular approach of supramolecular chemistry, we can coassemble neutral and cationic BTAs and control the overall properties of the polymer by simple monomer mixing. Moreover, this platform offers a versatile approach toward functionalization. The core can be efficiently loaded with a hydrophobic guest molecule, while the exterior can be electrostatically complexed with siRNA. It is demonstrated that both compounds can be delivered in living cells, and that they can be combined to enable a dual delivery strategy. These results show the advantages of employing a modular system and pave the way for application of supramolecular polymers in intracellular delivery. © 2016 American Chemical Society.

Vanderzwaag D.,Institute for Complex Molecular Systems | DeGreef T.F.A.,Institute for Complex Molecular Systems | Meijer E.W.,Institute for Complex Molecular Systems
Angewandte Chemie - International Edition | Year: 2015

Living large: Rational design of self-assembly pathways has been demonstrated in supramolecular polymers. By controlling the concentration of an aggregation-competent monomer through intramolecular interactions, living supramolecular polymerization conditions were achieved. This universal approach can be used to obtain aggregates of well-defined length and narrow dispersity, and allows access to new supramolecular polymer architectures. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Loading Institute for Complex Molecular Systems collaborators
Loading Institute for Complex Molecular Systems collaborators