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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...)
 

Liste der Veröffentlichungen

Interplay between domain microstructure and nematic order in liquid crystalline/isotropic block copolymers
R. Ivanova, R. Staneva, S. Geppert, B. Heck, B. Walter, W. Gronski, B. Stühn. Coll. Polym. Science 282, 810-824 (2004)
Nematic and Smectic Surface Order in the Isotropic-Phase of Low Molar-Mass and Polymeric Liquid-Crystals
S. Immerschitt, H. Elben, H. Holthoff, G. Strobl. Berichte der Bunsen-Gesellschaft - Physical Chemistry Chemical Physics 98, 376-382 (1994)
Model treatment of tensile deformation of semicrystalline polymers: Static elastic moduli and creep parameters derived for a sample of polyethylene
Ke Hong, Ankur Rastogi, Gert Strobl. Macromolecules 37, 10174-10179 (2004)
Equations describing lamellar structure parameters and melting points of polyethylene-co-(butene/octene)s
Tai-Yon Cho, Barbara Heck, Gert Strobl. Coll. Polym. Science 282, 825-832 (2004)
A model treating tensile deformation of semi-crystalline polymers: Quasi-static stress-strain relationship and viscous stress determined for a sample of polyethylene
K. Hong, A. Rastogi and G. Strobl. Macromolecules 37, 10165 (2004)
Crystallization of s-polypropylene: a qualitative change in the kinetics induced by the temperature of the melt
Barbara Heck, Gert Strobl. Coll. Polym. Science 282, 511-513 (2004)
Summary and conclusions: Progress in our understanding of instabilities in thin films
G. Reiter. Eur. Phys. J. E, 12, 465 –468 (2003)
Self-Assembly of CoPt3 Nanoparticle Rings Based on Phase-Separated Hexadecylamine Droplet Structure
Leonid V. Govor, Gottfried H. Bauer, Günter Reiter, Elena Shevchenko, Horst Weller, Jürgen Parisi. Langmuir 19, 9573-9576 (2003)
Dewetting near the Glass Transition: Transition from a Capillary Force Dominated to a Dissipation Dominated Regime
Pascal Damman, Nancy Baudelet, Günter Reiter Phys. Rev. Lett. 91, 216101 (2003)
Model Experiments for a Molecular Understanding of Polymer Crystallization
G. Reiter. J. Polym. Sci. Part B Polym. Phys. 41, 1869-1877 (2003)
Chances and Challenges in Europe
G. Reiter, N. Hadjichristidis, M. Möller. Nature Materials 2, 67-69 (2003)
Effet autophobe et démouillage des couches minces de polymères
G. Reiter. L’Actualité Chimique, Janvier 2003, p. 12-17
Polymer Crystallization on Pre-patterned Substrates
G. Dorenbos, J.-U. Sommer, G. Reiter. J. Chem. Phys. 118, 784-791 (2003)
Thermodynamics of Formation, Reorganization and Melting of Confined Nanometer-sized Polymer Crystals
Andreas Röttele,Thomas Thurn-Albrecht, Jens-Uwe Sommer, Günter Reiter. Macromolecules 36, 1257-1260 (2003)
Outlook and open questions: A personal view
Günter Reiter and Jens-Uwe Sommer. In Lecture Notes in Physics: "Polymer Crystallization: Observations, Concepts and Interpretations". Eds. Jens-Uwe Sommer and Günter Reiter, p.378-382, 2003
A Generic Model for Growth and Morphogenesis of Polymer Crystals in Two Dimensions
Jens-Uwe Sommer and Günter Reiter. In Lecture Notes in Physics: "Polymer Crystallization: Observations, Concepts and Interpretations". Eds. Jens-Uwe Sommer and Günter Reiter, p.153-176, 2003
Crystallization of Polymers in Thin Films: Model experiments
Günter Reiter, Gilles Castelein and Jens-Uwe Sommer. In Lecture Notes in Physics: "Polymer Crystallization: Observations, Concepts and Interpretations". Eds. Jens-Uwe Sommer and Günter Reiter, p.131-152, 2003
Polymer Crystallization: Obervations, Concepts and Interpretations
Editors: Jens-Uwe Sommer and Günter Reiter. Lecture Notes in Physics 606 (2003), Springer Berlin/Heidelberg, ISSN 1616-6361
Dewetting of thin polymer films at temperatures close to the glass transition
G. Reiter, M. Sferrazza, P. Damman. Eur. Phys. J. E 12, 133–138 (2003)
Editorial on "Focus point": Unstable thin films
A.M. Donald, J.F. Joanny,M. Moller,G. Reiter. Eur. Phys. J. E 12, 359-360 (2003)
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