Binäre Mesokristalle

Forscherteam unter Konstanzer Leitung erzeugt erstmals dreidimensionale Mesokristalle aus zwei unterschiedlichen Typen von Nanokristallen – Platin und Magnetit. Dies legt den Grundstein für die Synthese neuartiger nanostrukturierter Festkörper mit bisher unerforschten Eigenschaften.


Phase behaviour in 2D assemblies of dumbbell-shaped colloids generated under geometrical confinement

Rouven Stuckert, Anton Lüders, Alexander Wittemann, Peter Nielaba

The structure formation and the phase behaviour of monolayers of dumbbell-shaped colloids are explored. For this, we conduct Langmuir–Blodgett experiments at the air/water interface and conventional Brownian dynamic simulations without hydrodynamic interactions. Using Voronoi tessellations and the probability density of the corresponding shape factor of the Voronoi cells p(z), the influence of the area fraction f on the…


Origin of the Anisotropy and Structure of Ellipsoidal Poly(fluorene) Nanoparticles

Annika Sickinger  and Stefan Mecking

Polymer nanoparticles with a nonspherical shape are difficult to access and rare. Heterophase Suzuki–Miyaura polycondensation can yield distinct ellipsoidal poly(9,9′-dioctylfluorene) nanoparticles. We reveal the origin of this unusual particle shape by a combination of experimental approaches. Given sufficient chain mobility, enabled by the choice of a suitable organic solvent, also prefabricated oligomers with a DPn ≥ ca. 10 and polymers can form…


Simple Determination of Gold Nanocrystal Dimensions by Analytical Ultracentrifugation via Surface Ligand-Solvent Density Matching

Guillermo González-RubioHolger HilbertRose RosenbergBing NiLisa FuhrerHelmut Cölfen

Analytical ultracentrifugation (AUC) is a powerful technique to observe colloidal nanocrystals (NCs) directly in solution and obtain critical information about their physical-chemical properties. Nevertheless, a more comprehensive implementation of AUC for the characterisation of such a class of crystalline colloids has been traditionally impaired by the requirement of having a priori knowledge of…


Synthesis of ultrathin metal oxide and hydroxide nanosheets using formamide in water at room temperature

Zongkun Chen,   Minghua Huang   and  Helmut Cölfen  

The rational preparation of ultrathin two-dimensional metal oxide and hydroxide nanosheets is the first and crucial step towards their utilization in both fundamental research and practical applications. From the perspective of the production cost, the further development of such materials remains a challenging task. Therefore, it is highly desirable to synthesize these materials via a simple and general strategy at room temperature.…


Immobilization of (Aqueous) Cations in Low pH M-S-H Cement

by Maximilian R. Marsiske,  Christian DebusFulvio Di LorenzoEllina BernardSergey V. Churakov and Cristina Ruiz-Agudo

Incorporation of heavy metal ions in cement hydrates is of great interest for the storage and immobilization of toxic, hazardous, and radioactive wastes using cementitious matrix. Magnesium silicate hydrate (M-S-H) is a low pH alternative cementitious binder to commonly used Portland cement. Low pH cements have been considered as promising matrix for municipal and nuclear…


Critical Casimir interactions of colloids in micellar Q1 critical solutions

Laurent Helden, Timo Knippenberg, Li Tian, Aubin Archambault, Felix Ginotb
and Clemens Bechinger

We study the temperature-dependence of critical Casimir interactions in a critical micellar solution of
the nonionic surfactant C12E5 dissolved in water. Experimentally, this is achieved with total internal
reflection microscopy (TIRM) which measures the interaction between a single particle and a flat wall.
For comparison, we also studied the pair interactions of a two dimensional layer of…


Weder flüssig noch fest

Entdeckung von flüssigem Glas wirft Licht auf das alte wissenschaftliche Problem des Glasübergangs: Ein interdisziplinäres Forschungsteam der Universität Konstanz entdeckt einen neuen Aggregatzustand, flüssiges Glas, mit bisher unbekannten Strukturelementen – neue Erkenntnisse über die Eigenschaften von Glas und seine Übergänge.