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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

Nucleation Assisted through the Memory of a Polymer Melt: A Different Polymorph Emerging from the Melt of another One
Brahim Bessif, Barbara Heck, Thomas Pfohl, Cuong Minh Quoc Le, Abraham Chemtob, Valentina Pirela, Justine Elgoyhen, Radmila Tomovska, Alejandro Müller, Günter Reiter. Macromolecules 56 (2023) 1461–1470
Tuning the hydraulic resistance by swelling-induced buckling of membranes in high-aspect-ratio microfluidic devices
Claas-Hendrik Stamp, Binyam Solomon, Friederike Lang, Efstathios Mitropoulos and Thomas Pfohl. Lab Chip 23 (2023) 3662-3670
Reversible Dehydration-Hydration of Poly(ethylene glycol) in Langmuir Monolayers of a Diblock Copolymer Inferred from Changes in Filament Curvature
Emna Khechine, Sebastian Noack, Helmut Schlaad, Jun Xu, Günter Reiter, Renate Reiter. Langmuir 39 (2023) 2710–2718
Improving the order of crystalline regions of poly(3-hexylthiophene) by crystallization from the self-nucleation domains
Mina Alizadehaghdam, Farhang Abbasia, and Günter Reiter. Thermochimica Acta 717 (2022) 179352
Determining Entanglement Molar Mass of Glassy Polyphenylenes Using Mechanochromic Molecular Springs
Maximilian Raisch, Günter Reiter, Michael Sommer. ACS Macro Lett. 11, 760–765, 2022
Editorial on the Special Topic “Polymer Crystallization”
Jun Xu, Günter Reiter, and Rufina G. Alamo. Crystals 12, 618 (2022)
In situ dissolution and swelling of confined lamellar polymer crystals through exposure to humid air
Brahim Bessif, Thomas Pfohl, Barbara Heck, Yaser Alshetwi, Emna Khechine, Jun Xu, and Günter Reiter. Macromolecules 55, 6015–6022, 2022
The memory of thin polymer films generated by spin coating
Günter Reiter, Farzad Ramezani, Jörg Baschnagel. EPJE 45 (2022) 51
Bacteria-on-a-bead: probing the hydrodynamic interplay of dynamic cell appendages during cell separation
Nora Sauter, Matteo Sangermani, Isabelle Hug, Urs Jenal, and Thomas Pfohl. Biology Communications 5 (2022) 1093
Crystallization of copolymers: formation of alternating periodic structures and concepts for their modification
Brahim Bessif. Inaugural-Dissertation der Fakultät für Mathematik und Physik, 2022
Illumination of a Conjugated Polymer with Visible Light to Control Crystallization and Enhance Photoluminescence
Yaser AlShetwi. Inaugural-Dissertation zur Erlangung des Doktorgrads der Fakultät für Chemie und Pharmazie, 2022
Semi-crystalline poly(thioether) prepared by visible-light-induced organocatalyzed thiol-ene polymerization in emulsion
Cuong Minh Quoc Le, Gautier Schrodj, Ibrahima Ndao, Brahim Bessif, Barbara Heck, Thomas Pfohl, Günter Reiter, Justine Elgoyen, Radmila Tomovaska and Abraham Chemtob. Macromol. Rapid Commun. 43 (2022) 2100740
Illumination of Conjugated Polymers Reduces Nucleation Probability and Slows Down Crystal Growth Rate
Yaser AlShetwi, Brahim Bessif, Michael Sommer, Günter Reiter. Macromolecules 54, 2021, 11478–11485
Primary nucleation in metastable solutions of poly(3-hexylthiophene)
Tianyu Wu, Sivasurender Chandran, Yao Zhang, Tianze Zheng, Thomas Pfohl, Jun Xu, Günter Reiter. Macromolecules 55 (2022) 3325–3334
An investigation on the heat dissipation in Zn-substituted magnetite nanoparticles, coated with citric acid and pluronic F127 for hyperthermia application
Sara Shatooti, Morteza Mozaffari, Günter Reiter, Diana Zahn, Silvio Dutz. Physica B: Physics of Condensed Matter 625 (2022) 41346856
Successive melting and crystallization of poly(3-hexylthiophene) in the melt-memory domain versus isotropic melt domain
Mina Alizadehaghdam, Farhang Abbasi, Günter Reiter. Journal of Materials Science 56 (2021) 19723–19737
Transparent, thermoplastic, aliphatic polyesters through crystallization under molecular confinement
Maziar Matloubi, Melika Sarema, Barbara Heck, Günter Reiter and V. Prasad Shastri. Matter 6 (2023) 3057-3074
Heat dissipation in Sm3+ and Zn2+ co-substituted magnetite (Zn0.1SmxFe2.9-xO4) nanoparticles coated with citric acid and pluronic F127 for hyperthermia application
S. Shatooti, M. Mozaffari, G. Reiter, D. Zahn, S. Dutz. Scientific Reports 11 (2021) 16795
Controlled Switching from the Growth of Mono-Lamellar Polymer Crystals to the Formation of Stacks of Uniquely Oriented Lamellae
Weixiang Chen, Brahim Bessif, Renate Reiter, Jun Xu, Günter Reiter. Macromolecules 54 (2021) 8135–8142
Self-Seeding Procedure for Obtaining Stacked Block Copolymer Lamellar Crystals in Solution
Brahim Bessif, Thomas Pfohl and Günter Reiter. Polymers 13 (2021) 1676
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