Macro Awards 2017



A) Macromolecular Colloquium, Freiburg, Germany (February 15-17, 2017)

The Macromolecular Journals sponsored prizes for the best poster presentations. The prizes were awarded to:

a1) Reversible Transition between Anisotropic and Isotropic Thermal Transport in Polyurethane Foams

Bernd A. F. Kopera,* 1 Markus Retsch,1 Mokit Chau,2 Vanessa R. Machado,2 S. Mastour Tehrani,2 M. A. Winnik,2 E. Kumacheva 2

1 Physical Chemistry – Polymer Systems, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany; Email: Bernd.Kopera@uni-bayreuth.de

2 Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada

Prize Winner Bernd Kopera with colleagues

Polyurethane foams are well established thermal insulators and find commercial application as insulating foams. However, control over the thermal transport properties in different directions is hard to achieve with isotropic foams but imperative for future dynamic insulation materials.[1] Here, we demonstrate elastic polyurethane foams with anisotropic lamellar microstructure formed by freeze-casting of water based polyurethane dispersions (Figure 1). Freeze-casting is an emerging technology used to create freestanding foams with anisotropic structure and properties.[2] This anisotropy results in orientation-dependent mechanical and thermal transport properties. Most importantly, the thermal conductivity and thermal diffusivity can be reversibly transitioned between an anisotropic and an isotropic state. This transition is achieved by altering the thermal conductivity and diffusivity of the surrounding atmosphere either by changing the pressure of the gas or its composition.

Figure 1. Left: Micro computed tomography showing the anisotropic porous structure of the PU-foams. Middle: Thermal conductivity of the PU-foam as a function of helium pressure, parallel and perpendicular to the direction of ice growth. Right: Reversible transition between isotropic and anisotropic thermal conductivity over several cycles from vacuum to helium and back.

[1] B. P. Jelle, Energy and Buildings 2011, 43, 2549.

[2] B. Wicklein, A. K., G. Salazar-Alvarez, F. Carosio, G. Camino, M. Antonietti, L. Bergstrom, Nature nanotechnology 2015, 10, 277.

 

a2) Let’s Get Things in Order: Sequence Controlled Anionic Polymerization of Aziridines

Elisabeth Rieger,* Tassilo Gleede, Angelika Manhart, Laura Thomi, Manfred Wagner, Frederik R. Wurm

Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany; Email: rieger@mpip-mainz.mpg.de

Elisabeth Rieger and the winning poster on sequence controlled anionic polymerization

We recently started the investigation of the anionic polymerization of aziridines: the poster summarizes our efforts to establish sulfonamide-activated aziridines as a novel monomer family, with different (functional) groups, for the living anionic polymerization. A systematic investigation of the polymerization kinetics is represented to determine the influence of different solvents and counter ions, monitored in-situ by 1H NMR-spectroscopy. The poster illustrates the simultaneous copolymerization of up to five competing monomers in an one-pot approach, examined by real-time 1H NMR spectroscopy. The monomer sequence is gracefully adjusted by the monomer reactivity, related to the electron-withdrawing effect of the sulfonamide groups. This allows us for the first time to mix different monomers and control their incorporation in a copolymer with structures, ranging from random over gradient to block-like composed copolymers. We believe that the anionic polymerization of aziridines will provide straightforward access to novel polyamides and –amines with interesting properties for a lot of applications.

 

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B) International Conference on the Reaction Engineering of Polyolefins, Geleen/Maastricht, The Netherland (June 6-9, 2017)

The Macromolecular Journals sponsored a prize for the best poster presentation. The prize was awarded to:

Triboelectric charging of polyethylene powders

Simon Jantač,* Ladislav Konopka, Juraj Kosek

University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic; Email: simon.jantac@vscht.cz

Simon Jantač and the winning poster on triboelectric charging

During manufacturing and transportation, the powder particles undergo collisions with other particles or a device wall. When a particle collides with another object a charge is redistributed. For example, in the manufacturing process of polyethylene (PE), if the charge reaches a critical value, particles will adhere to a reactor wall, thus forming particle sheets on the wall. The mechanisms of triboelectric charging are still poorly understood. To study the triboelectric charging we constructed the ‘cascade method‘ apparatus. Additionally, we constructed a shaking apparatus and compared the obtained charging dynamics results to those of the ‘cascade method’ apparatus. The results indicate that not only the dynamics of charging, but also the saturation charge (maximum charge at given conditions) are proportional to the energy of collisions. Moreover, our results indicate that the increase in saturation charge at elevated temperatures could be caused by a particle softening.

 

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C) International Symposium on Polymer Analysis and Characterization, Linz, Austria (June 11-14, 2017)

The Macromolecular Journals sponsored a prize for the best poster presentation. The prize was awarded to:

Degradation Assessment of Ethylene Vinyl Acetate Encapsulant in Crystalline Silicon Photovoltaic Module using Positron Annihilation Lifetime Spectroscopy

Hideaki Hagihara,* Masao Kunioka, Hiroyuki Suda, Yukiko Hara, Atsushi Masuda

National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki, Japan; Email: h-hagihara@aist.go.jp

Hideaki Hagihara and the winning poster on the degradation ethylene vinyl acetate encapsulants

Ethylene vinyl acetate copolymer (EVA) encapsulants detached from the crystalline-Si photovoltaic (PV) modules after damp heat (DH) testing were evaluated by positron annihilation lifetime spectroscopy (PALS). A reduction in free-volume hole size, which indicates the progress of deacetylation, was observed. The difference in lifetime (Δτ) between the initial sample and DH-tested samples clearly increased after DH testing for 3000 h. The increase in Δτ was correlated with the acetic acid concentration in the EVA estimated by ion chromatography. The depth profile analysis by slow positron beam PALS revealed that Δτ at the near-surface region of the Si-cell side was significantly larger than that of the other parts. This result indicates that deacetylation near the Si cell/EVA interface is accelerated during the DH testing.

 

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D) International Conference on Self-Healing Materials, Friedrichshafen, Germany (June 25-28, 2017)

The Macromolecular Journals sponsored prizes for the best poster presentations. The prizes were awarded to:

d1) Heal-On-Command by Magnetic Heating

Ahmad Shaaban,* Nico Hohlbein, Annette M. Schmidt

Universität zu Köln, Cologne, Germany; Email: ahmad.shaaban@uni-koeln.de

Ahmad Shaaban, author of the winning poster on self-healing by magnetic heating

The combination of magnetic nanoparticles with soft materials offers new possibilities towards smart materials that can be manipulated by external magnetic fields. In particular, the local heat dissipation by magnetic nanostructures in oscillating electromagnetic fields provides the option to increase the temperature locally and stimulate dynamic processes, e.g. self-healing.[1-3] We investigate the influence of magnetic nanoantennas in an acrylate-based ionomeric elastomer on the heating and healing characteristics. Furthermore the influence of the particle on the dynamic and mechanical properties of the used ionomers is taken into account. The dissipated thermal energy in the particles’ environment triggers a thermal transition in dynamic polymeric matrices activating the self-healing process.[4] We show that the heat development and the resulting temperature profile can effectively be predicted and modelled for various self-healing matrices on the base of accessible material characteristics and geometry.

[1] Shaaban, A.; Schmidt, A. M. Smart Mater. Struct. 2016, 25, 1.

[2] Hohlbein, N.; Shaaban, A.; Bras, A. R.; Pyckhout-Hintzen, W.; Schmidt, A. M. Phys. Chem. Chem. Phys. 2015, 17, 21005.

[3] Schmidt, A. M. Colloid Polym. Sci. 2007, 285, 953.

[4] Hohlbein, N.; Shaaban, A.; Schmidt, A. M. Polymer 2015, 69, 301.

 

d2) Thermally Adjustable Hindered Diaminodisulfides as a Dynamic Covalent Linkage toward Long-Life Polymers

Akira Takahashi,1 Raita Goseki,1,2 Hideyuki Otsuka* 1,2

1 Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Japan; Email: a-takahashi@polymer.titech.ac.jp

2 Department of Chemical Science and Engineering, Tokyo Institute of Technology, Japan

Akira Takahashi, author of the winning poster on hindered diaminodisulfides

Dynamic covalent bonds that have intrinsic exchangeability induced by readily usable stimuli are important library for designing wider variation of long-life polymers. Herein we focused on 2,2,6,6-tetramethylpiperidine-1-sulfanyl (TEMPS) dimers with moderate thermal dissociability,[1] and investigated their dynamic covalent chemistry. We established versatile synthetic route for the various derivatives of the dimer, including polymers, via modifiable diol compound. Thermally adjustable exchangeability of the dimer based on highly air-stable TEMPS radicals was revealed, which afforded reversible depolymerization-recovery of the linear polyurethane and quantitative damage healability of the network polyurethane incorporated with the dimer.[2]

[1] J. E. Bennett, H. Sieper, P. Tavs, Tetrahedron 1967, 23, 1697.

[2] A. Takahashi, R. Goseki, H. Otsuka, Angew. Chem. Int. Ed. 2017, 56, 2016.

 

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E) Europe Africa Conference of the Polymer Processing Society, Dresden, Germany (June 26-29, 2017)

The Macromolecular Journals sponsored a prize for the best poster presentation. The prize was awarded to:

Morphology-Property Behavior of Semi-Crystalline Polymers in Injection Molded Parts

Yvonne Spörer,* 1 Carolina Blanco,2 Martin Zimmermann,1 Ines Kühnert1

1 Leibniz-Institut für Polymerforschung Dresden e.V., Dresden, Germany; Email: spoerer@ipfdd.de

2 Technische Universität Dresden, Dresden, Germany

The poster authors from left to right: Martin Zimmermann, Yvonne Spörer, Carolina Blanco and Ines Kühnert.

The morphology in injection molded semi-crystalline polymers is mainly affected by the processing parameters (mold and melt temperature, injection speed, pressure). Especially in the skin-core regions the morphology belongs to the cooling rate during the process. Another effect depends on the melt flow conditions and the mold design which can occur in the formation of weld lines. Possible reason for the development of weld lines is the division of the melt flow because of the usage of flow obstacles or more than one gate to create complex parts. This characteristic leads to optical and/ or mechanical weaknesses because of the structure orientation depending on thermodynamic and morphological behavior of the polymer chains. For the better understanding of the specific orientation of the molecular chains in semi-crystalline injection molded parts the poster gave an overview about the influence of processing conditions and the relation to mechanical properties.

 

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