Uni-Logo
You are here: Home Publications
Document Actions

Publications

bibliothek-720x.jpgwx121.jpg

Select the year of publication...

2016-2018 2019 2020 2021
2004-2006  2007-2009 2010-2012  2013-2015
before 1990 1991-1995  1996-2000 2001-2003

 

 ...or go to the

advanced search form.

 

Recent Publications


Measurements of periodically perturbed dewetting force fields and their consequences on the symmetry of the resulting patterns

2021-rei-02.jpgWe studied the origin of breaking the symmetry for moving circular contact lines of dewetting polymer films suspended on a periodic array of pillars. There, dewetting force fields driving polymer flow were perturbed by elastic micro-pillars arranged in a regular square pattern. Elastic restoring forces of deformed pillars locally balance driving capillary forces and broke the circular symmetry of expanding dewetting holes. The observed envelope of the dewetting holes reflected the symmetry of the underlying pattern, even at sizes much larger than the characteristic period of the pillar array, demonstrating that periodic perturbations in a driving force field can establish a well-defined pattern of lower symmetry. For the presented system, we succeeded in squaring the circle. [more...]



Surface-modified elastomeric nanofluidic devices for single nanoparticle trapping

pfohl-02.jpgOur work focuses on the development of simpler and effective production of nanofluidic devices for high-throughput charged single nanoparticle trapping in an aqueous environment. Single nanoparticle confinement using electrostatic trapping has been an effective approach to study the fundamental properties of charged molecules under a controlled aqueous environment. Conventionally, geometry-induced electrostatic trapping devices are fabricated using SiOx-based substrates and comprise nanochannels imbedded with nanoindentations such as nanopockets, nanoslits and nanogrids. These geometry-induced electrostatic trapping devices can only trap negatively charged particles, and therefore, to trap positively charged particles, modification of the device surface is required. [more...]



Changes in Surface Free Energy and Surface Conductivity of Carbon Nanotube/Polyimide Nanocomposite Films Induced by UV Irradiation

am1c02654_0012.gifChanges in surface energy and electrical conductivity of polyimide (PI)-based nanocomposite films filled with carbon nanotubes (CNTs) induced by UV exposure are gaining considerable interest in microelectronic, aeronautical, and aerospace applications. However, the underlying mechanism of PI photochemistry and oxidation reactions induced by UV irradiation upon the surface in the presence of CNTs is still not clear. Here, we probed the interplay between CNTs and PIs under UV exposure in the surface properties of CNT/PI nanocomposite films.   [more...]


  
Continuous Illumination of a Conjugated Polymer Causes Strong Enhancement of Photoluminescence

jp1c01837_0009.jpgWe present measurements of absorbance and photoluminescence (PL) for films of poly(3-(2,5-dioctylphenyl)thiophene) (PDOPT) as a function of temperature (T) and time (t) of illumination. While having no detectable influence on absorbance of this conjugated polymer, our experiments clearly revealed that illumination of PDOPT caused a significant increase in the PL intensity (IPL(T,t)), that is, the emission probability of PDOPT. Without illumination, we always observed a decrease in IPL with time. An increase in IPL was only detectable when the sample was illuminated. [more...]



Self-Seeding Procedure for Obtaining Stacked Block Copolymer Lamellar Crystals in Solution

brahim-polymers.jpgWe examined the formation of self-seeded platelet-like crystals from polystyrene-block-polyethylene oxide (PS-b-PEO) diblock copolymers in toluene as a function of polymer concentration (c), crystallization temperature (TC), and self-seeding temperature (TSS). We showed that the number (N) of platelet-like crystals and their mean lateral size (L) can be controlled through a self-seeding procedure.  [more...]



Formation of Stacked Three-Dimensional Polymer “Single Crystals”

ma1c00081_0006.gif

Stacks of crystalline lamellae all having a uniquely oriented hexagonal shape, referred to as “3D (three-dimensional) single crystals”, were obtained via isothermal crystallization of isotactic polystyrene at a temperature close to the melting point. The height of the stacks of lamellae reached several micrometers corresponding to hundreds of superposed lamellar crystals. We propose that the mechanism of self-induced nucleation allowed propagating the orientation of the basal lamellar crystal to all other lamellae in the stack. [more...]



Concepts of nucleation in polymer crystallization

2021-xujun.jpgNucleation plays a vital role in polymer crystallization, in which chain connectivity and thus the multiple length and time scales make crystal nucleation of polymer chains an interesting but complex subject. Though the topic has been intensively studied in the past decades, there are still many open questions to answer. The final properties of semicrystalline polymer materials are affected by all of the following: the starting melt, paths of nucleation, organization of lamellar crystals and evolution of the final crystalline structures. [more...]



Optimization of Nanofluidic Devices for Geometry‐Induced Electrostatic Trapping

2021-pfo-01c.jpgNanoparticle trapping in a nanofluidic device utilizing geometry-induced electrostatic (GIE) potential trap is an efficient and robust way to perform nano‑object confinement and single particle studies. The GIE‑trapping is a passive method that solely depends on the device geometry and device-particle surface interaction. Therefore, optimization of a nanofluidic device based on experimental requirements, helps to achieve stiffer single-particle trapping. The efficiency of a GIE‑trapping device is defined in terms of residence time and trapping stiffness of the nanoparticle inside a potential trap. The present study reveals all crucial parameters that affect the device efficiency, particle trapping stiffness, and particle residence time. [more...]

 

List of Publications

Adapted Creep Test for the Study of Non-Equilibrated Thin Polymer Films
Farzad Ramezani. Inaugural-Dissertation zur Erlangung des Doktorgrades der Fakultät für Mathematik und Physik der Albert-Ludwigs-Universität Freiburg 2019
Tad Pili Play a Dynamic Role in Caulobacter crescentus Surface Colonization
Matteo Sangermani, Isabelle Hug, Nora Sauter, Thomas Pfohl, Urs Jenala. mBio 10:e01237-19 (2019)
Spatially resolved small-angle X-ray scattering for characterizing mechanoresponsive liposomes using microfluidics
Marzia Buscema, Hans Deyhle, Thomas Pfohl, Andreas Zumbuehl, Bert Müller. Materials Today Bio 1 (2019) 100003
Semicrystalline Non-Isocyanate Polyhydroxyurethanes as Thermoplastics and Thermoplastic Elastomers and Their Use in 3D Printing by Fused Filament Fabrication
Vitalij Schimpf, Johannes B. Max, Benjamin Stolz, Barbara Heck, and Rolf Mülhaupt. Macromolecules 52 (2019) 320-331
Self-Assembly of Oligo(phenylene-thiophene)s on Monolayer Graphene: Molecular Dynamics Simulations
Natalia Borzdun, Victor Nazarychev, Sergey Larin, Guenter Reiter, Sergey Lyulin. J. Phys. Chem. C, 123 (2019) 859–867
Functional macromolecular systems: kinetic pathways to obtain tailored structures
V. Abetz, K. Kremer, M. Müller, and G. Reiter. Macromolecular Chemistry and Physics 220 (2019) 1800334
Growth Kinetics of Stacks of Lamellar Polymer Crystals
Sumit Majumder, Hanna Busch, Purushottam Poudel, Stefan Mecking, and Günter Reiter. Macromolecules 51 (2018) 8738–8745
Self-Interference of Exciton Emission in Organic Single Crystals Visualized by Energy-Momentum Spectroscopy
Christian Schörner, Sajedeh Motamen, Laurent Simon, Günter Reiter, Richard Hildner. ACS Omega 3 (2018) 6728–6736
Formation of Periodically Modulated Polymer Crystals
Purushottam Poudel, Sumit Majumder, Sivasurender Chandran, Hui Zhang, Günter Reiter. Macromolecules 51 (2018) 6119–6126
Generating Nanoscopic Patterns in Conductivity Within a Poly(3-hexylthiophene) Crystal Via Bias-controlled Scanning Probe Nanolithography
Binghua Wang, Bin Zhang, Changyu Shen, Jingbo Chen, Günter Reiter. Macromolecules 51 (2018) 7692-7698
Systematic Control of Self-Seeding Crystallization Patterns of Poly(ethylene oxide) in Thin Films
Binghua Wang, Shaohua Tang, Yan Wang, Changyu Shen, Renate Reiter, Günter Reiter, Jingbo Chen, Bin Zhang. Macromolecules 51, 1626–1635 (2018)
Tuning relaxation dynamics and mechanical properties of polymer films of identical thickness
Marwa Kchaou, Pierre Alcouffe, Sivasurender Chandran, Philippe Cassagnau, Günter Reiter, and Samer Al Akhrass. Phys. Rev. E 97, 032507 (2018)
Highly n-doped graphene generated through intercalated terbium atoms
L. Daukiya, M. N. Nair, S. Hajjar-Garreau, F. Vonau, D. Aubel, J. L. Bubendorff, M. Cranney, E. Denys, A. Florentin, G. Reiter, and L. Simon. Phys. Rev. B 97, 035309 (2018)
Formation of Periodically Modulated Polymer Crystals
Purushottam Poudel. Inauguraldissertation 2018
Pneumatically Controlled Nanofluidic Devices for Contact-Free Trapping and Manipulation of Nanoparticles
Michael Adrian Gerspach, Nassir Mojarad, Deepika Sharma, Yasin Ekinci,and Thomas Pfohl. Part. Part. Syst. Charact. 2018, 1800161
Monitoring single-cell gene regulation under dynamically controllable conditions with integrated microfluidics and software
M. Kaiser, F. Jug, T. Julou, S. Deshpande, T. Pfohl, O. K. Silander, G. Myers, E. van Nimwegen, Nature Communications 9, 212 (2018)
Growth Kinetics of Stacks of Lamellar Crystals in Polymer Thin Films
Sumit Majumder. Inauguraldissertation 2018
Optical studies on indicators of order and disorder in films and crytals of a bulky substituted polythiophene
Fanuel Mugwanga Keheze. Inauguraldissertation 2018
Multiple structural transitions in Langmuir monolayers of charged soft-shell nanoparticles
Ahmed El-Tawargy, David Stock, Markus Gallei, Wael Ramadan, Mamdoh Shams El-Din, Günter Reiter, Renate Reiter. Langmuir 34, 3909−3917 (2018)
Thermodynamic origin of multi-layer structures in Langmuir polymer films
Volker Knecht, Günter Reiter, Renate Reiter. Langmuir 33 (2017) 11399–11405
Personal tools