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Recent Publications


Spatiotemporal Sequence of Interdependent Nucleation Mechanisms in Ultrathin Polymer Films

Da Huang, Rana Bakhshi, Raoul M. D'Anselme, Günter Reiter. Macromolecules, published online

Employing defined starting conditions of ultrathin molten poly(ethylene oxide) films on model solid substrates, we investigated the spatiotemporal sequence of interdependent mechanisms of crystal nucleation. Due to the limited number and the preferred conformation of polymer chains parallel to the substrate, primary nucleation favored edge-on lamellar crystals, which indirectly induced other subsequent nucleation pathways, enabled through the molten polymer chains accumulated at their peripheral fold surfaces. Both additional edge-on lamellar crystals and branched flat-on lamellar crystals were initiated. For long-chain polymers, spatial correlations between lamellar crystals across intervening noncrystalline regions were established through polymer chains incorporated within neighboring lamellae. (more...)


Nonmonotonic Variation of the Preferential Orientation of Lamellar Crystals in Films of Cold-Crystallized Poly(l-lactide) of Increasing Thickness and Molecular Weight

Decai Lin, Zebin Su, Yuxiang Chen, Jianquan Xu, Günter Reiter, Cuiyun Zhang, Xinping Wang. Macromolecules  59 (2026) 4970–4981

Using infrared reflection–absorption spectroscopy and atomic force microscopy, we revealed that polymer–substrate interactions, chain length, and film thickness critically influenced the morphology and orientation of lamellar crystals of poly(l-lactide) (PLLA) grown at a constant temperature. In contrast to the often-observed monotonic change from preferentially flat-on to edge-on crystals upon increasing film thickness, an unprecedented nonmonotonic change in the dominating orientation of lamellar crystals from edge-on to flat-on and back to edge-on was observed. In the thinnest films, size confinement and adsorption-induced alignment of the chains favored the nucleation and growth of edge-on lamellar crystals. Enhanced polymer–substrate interactions promoted the formation of edge-on lamellar crystals in the thinnest films with a higher molecular weight. (more..)


Properties of Charged Conjugated Polymers Deposited by Electrospraying on Substrates with an Insulating Oxide Layer

Anmol Arya, Solomon L. Joseph, Francois Vonau, Jean-Luc Bubendorff, Silvia Siegenführ, Laurent Simon, Günter Reiter. J. Phys. Chem. C 2026, 130, 5536–5546

In the course of electrospraying in a vacuum, polymers acquire electric charges, which are distributed along their backbone. Here, we demonstrate that these charges have a strong impact on the molecular ordering and spectroscopic properties of conjugated polymers when deposited on substrates with an insulating oxide layer. To this end, we electrosprayed varying amounts of poly(3-hexylthiophene) (P3HT) onto silicon substrates with oxide layers of different thickness. The resulting morphologies were explored by atomic force microscopy. The corresponding spectroscopic properties, including their changes in time upon illumination, were derived from photoluminescence (PL) measurements. On insulating substrates, charges were retained on the polymer chains, causing long-range electrostatic repulsion and the formation of largely separated droplet-like objects containing multiple chains. These objects exhibited significant PL intensities for photons with a wavelength (λ) less than ca. 600 nm, suggesting the lack of π–π stacking interactions between P3HT chains. (more...)


Reversible Metamorphosis of a Conjugated Polymer Induced by Photoexcitation

Solomon Joseph, Anmol Arya, Günter Reiter. Advanced Photonics Research 7 (2026) e202500311

Optoelectronic properties of materials are frequently examined through spectroscopic tools based on the absorption and emission of (visible) photons. Typically, one assumes that these transient characterization processes do not cause observable change of these properties because of the low power of the employed light sources. However, for flexible conjugated polymers in a medium of low viscosity, it is decidedly unclear whether photoexcitation of electrons on the backbone of a long polymer chain has an influence on macromolecular conformations and the corresponding intermolecular interactions. Here, we provide clear experimental evidence that continuous absorption of photons progressively causes persistent changes in the spectroscopic properties of conjugated polymers, accompanied by microscopically observable changes in their spatial distribution within a low-viscosity matrix. By contrast, all these changes were completely absent in nonilluminated parts of the same sample.(more...)


Temperature dependence of crystal – melt coexistence for supported polyethylene filaments

Da Huang, Thorsten Hugel, Bizan N. Balzer, Günter Reiter. Nature Communications 16 (2025) 11127

The broken symmetry of molecular interactions at interfaces is causing that crystals are often covered by a thin liquid layer of their own melt. Such crystal–melt coexistence can be related to phenomena of surface premelting, secondary nucleation and melting point depression, particularly important for small systems. Here, we employed intermittent-contact mode atomic force microscopy imaging on nanoscopic semi-cylindrical filaments of polyethylene on a substrate to observe that these filaments contained a crystalline core bounded by molten regions of rather uniform width,  W_soft= (9 ± 2) nm at room temperature, which increased reversibly with temperature T. Filaments smaller than ca. 2∙W_soft (T) were completely molten. The values of W_soft (T) compared favorably with theoretically predicted characteristic length scales in the context of nucleation, surface premelting and the melting point depression of finite size crystals. Altogether, we show that these three phenomena are related and dominated by the intermolecular forces acting at crystal surfaces.(more...)

 

List of Publications

Controlling the Pore Size in Conjugated Polymer Films via Crystallization-Driven Phase Separation
Shaowen Guo, Changyu Shen, Jingbo Chen, Günter Reiter, Bin Zhang. Soft Matter 15 (2019) 2981-2989
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)
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