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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

Comparative Study of Individual and Collective Rotational Motion in Mixtures of Liquid Crystalline Side Group Polymers and Low Molecular Weight Mesogens
H. Seiberle, W. Stille and G. Strobl. Macromolecules 23, 2008 (1990)
Interdiffusion of Polymer Thin Films as Determined by Scattering Techniques
M. Stamm, D. Brautmeier, G. Reiter, M. Foster. Proceed. of the 48th ANTEC 1990 Dallas, USA on "Plastics in the Environment: Yesterday, Today and Tomorrow" 36, 825 (1990)
Characterisation of Polymer Surfaces and Interfaces by Reflectivity and Interference Techniques
M. Stamm, G. Reiter, M. Foster, H. Motschmann, S.Hüttenbach, C. Toprakcioglu. Sci. and Eng., ACS/PMSE 62, 843 (1990)
Interfacial Mixing of Polymers as Investigated by X-ray and Neutron Reflectometry
M. Stamm, G. Reiter, S. Hüttenbach, M. Foster. ACS Polymer preprints 31, 73 (1990)
X-ray Reflectometer for Study of Polymer Thin Films and Interfaces
M. Foster, M. Stamm, G. Reiter, S. Hüttenbach. Vacuum, 41, 1441-1444 (1990)
Positron Lifetime Investigations on Linear Polyethylene Compared to Branched Polyethylene
G. Reiter, P. Kindl. phys. stat. sol. (a) 118, 161-168 (1990)
Concentration-Dependence of the Flory-Huggins Interaction Parameter of a Polymer Blend as Determined by Small-Angle X-Ray-Scattering Experiments
T. Koch, G.R. Strobl. Journal of Polymer Science B - Polymer Physics 28, 343-353 (1990)
Positron Lifetime Investigations on Polymethylmethacrylate
P. Kindl, G. Reiter. In: Positron Annihilation, Ed. L. Dorikens-Vanpraet, M. Dorikens, and D. Segers, World Scientific, Singapore 1989 (p.806)
A Neutron Reflectometer for the Investigation of Solid and Liquid Interfaces
M. Stamm, G. Reiter, S. Hüttenbach. Physica B 156, 564-566 (1989)
Kinetics of Relaxation and Unmixing in Polymer Blends as Studied by X-Ray-Scattering
G. Strobl. Makromolekulare Chemie - Macromolecular Symposia 26, 413-429 (1989)
X-Ray-Scattering Study of Molecular Order in a Liquid Crystal-Side Group Polysiloxane
W. Hotz, G. Strobl. Colloid and Polymer Science 267, 889-898 (1989)
Interdiffusion in the Partially Miscible Polymer Blend of Deuterated Polystyrene and Poly(styrene-co-bromostyrene)
F. Bruder, R. Brenn, B. Stühn, G.R. Strobl. Macromolecules 22, 4434-4437 (1989)
Structure Relaxation after Temperature Jumps in Homogeneous Polystyrene Poly(styrene-co-bromostyrene) Blends
G.R. Strobl, G. Urban. Colloid and Polymer Science 266, 398-404 (1988)
Soliton dynamics and impurities in the Pariser-Parr-Pople model of alternating trans-polyacetylen
R. Markus, W. Förner, J. Ladik. Solid States Communications 68, 135-138 (1988)
Investigations on Low Temperature Transitions and Time Effects of Branched Polyethylene by the Positron Lifetime Technique
P. Kindl, G. Reiter. phys. stat. sol. (a) 104, 707 (1987)
Small-Angle X-Ray-Scattering Study of Spinodal Decomposition in Polystyrene Poly(styrene-co-bromostyrene) Blends
H. Meier, G.R. Strobl. Macromolecules 20, 649-654 (1987)
Surface Melting in Melt-Crystallized Linear Polyethylene
Y. Tanabe, G.R. Strobl, E.W. Fischer. Polymer 27, 1147-1153 (1986)
Thermally Reversible Phase Separation in Polystyrene Poly(styrene-co-4-bromostyrene) Blends
G.R. Strobl, J.T. Bendler, R.P. Kampour, A.R. Shultz. Macromolecules 19, 2683-2689 (1986)
Structure Evolution during Spinodal Decomposition of Polymer Blends
G.R. Strobl. Macromolecules 18, 558-563 (1985)
Dielectric Relaxation of Liquid Crystalline Polyacrylates and Polymethacrylates
R. Zentel, G.R. Strobl, H. Ringsdorf. Macromolecules 18, 960-965 (1985)
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