Rheology, sticky chain and sticker dynamics of supramolecular elastomers based upon cluster-forming telechelic linear and star polymers

Mordvinkin, A., et.al. Macromolecules, 2021, 5065–5076, https://doi.org/10.1021/acs.macromol.1c00655

We elucidate the properties of unentangled telechelic poly(isobutylene) (PIB) chains in bulk forming dynamic micellar networks mediated by endgroups capable of hydrogen-bonding and π–π interactions. The effects of the molecular architecture and type of endgroup on the properties of networks are studied by a combination of small-angle X-ray scattering (SAXS), rheology, low-resolution NMR, and dielectric spectroscopy (DS). It is found that star-shaped molecules form more time-stable networks with larger and somewhat more distantly arranged aggregates compared to their linear counterparts.Copyright © 2021 The Authors. Published by American Chemical Society.

Towards in-line detection of thermal polymer degradation

Funtan, A., et. al. Outreach-Article, 2021, DOI:10.32907/RO-125-1679181891

Link zu ARTICLE and VIDEO https://researchoutreach.org/articles/towards-in-line-detection-thermal-polymer-degradation/

Polymers are an indispensable part of modern society, found in almost every product we use, including machine and engine components. But polymers degrade, and they need close monitoring to make sure this doesn’t cause structural materials or devices to fail. We already have many ways to assess polymer degradation in the lab, but monitoring polymers while they’re in use is much harder. In a new experiment, Professor Wolfgang Binder and MSc Alexander Funtan from Martin Luther University Halle-Wittenberg, along with ALTANA AG and its division ELANTAS who initiated the research, have established the potential for a real-time sensor system to detect thermal degradation of a class of polymers called poly(ester imide)s (PEIs). Their new approach will be important for all commercial electric engines, where these materials are used for insulation. Published with the permission of Creative Commons Licence(CC BY-NC-ND 4.0).

Vitrimers based on Bio-derived Chemicals: Overview and Future Prospects

Balaji, K., et. Al. Chem. Eng. J., 2021, 133261, https://doi.org/10.1016/j.cej.2021.133261

The perspective of using recyclable and biobased materials in the vitrimeric concept is attractive, as current polymers’ regulations, their recyclabilities, together with the need to reduce CO2-emission, is pressing. Many of these demands can be resolved through state-of-the-art bio-vitrimeric materials displaying thermoset like mechanical and thermal properties as well as thermoplastic like malleable and thus recyclable properties. This article emphasizes the current needs of vitrimers based on bio-derived chemicals, including their recycling, reprocessing, and self-healing properties, along with their advantages and potential obstacles from todays’ perspective. We also identify potential bio-derivatives as attractive building blocks for vitrimers because of their potential for sustainability. © 2021 Elsevier B.V. All rights reserved.

Enzymatic degradation of synthetic polyisoprenes via surfactant-free polymer emulsification

Adjedje, V.B.K., et. al. Green Chemistry, 2021, 23, 9433-9438, DOI: 10.1039/D1GC03515K

Polyisoprenes are ubiquitously applied in industry as motor mounts, pipe gaskets, sporting equipment and many other molded and mechanical goods. We report the enzymatic degradation of a synthetic polyisoprene with a cis:trans ratio of 56:27 for the first time. Utilizing a bioinspired surfactant-free emulsification strategy in water resulted in substantially increased activities with the Latex Clearing Protein LcpK30. Published with a permission of the Green Chemistry 2021.

Materialien für die “Ewigkeit”: selbstheilende Polymere – auch rezyklierbar!

Marinow, A., et. al. Chemie in unserer Zeit, ASAP, 2021, ciuz.202100014R1

Wie man die Lebensdauer von Materialien verlängern kann hat die Menschheit nicht erst im 21. Jahrhundert beschäftigt. So hat der Begriff „Verlängerung der Nutzungsdauer eines Materials“ zusätzlich Bedeutung vor allem im Bereich der Konsumprodukte erhalten, nicht zuletzt über den Wunsch der Vermeidung von Müll und von emittierten Kohlenstoffdioxid. Die Nutzung von reversiblen chemischen Bindungen erlaubt es Polymermaterialien mit selbstheilenden Eigenschaften herzustellen, aber auch neue Konzepte der Rezyklierung/ Wiederverwendung von Polymeren zu ermöglichen – damit kann die Nutzungsdauer von Batterien, Solarzellen, Mobiltelefonen oder Gummireifen verlängert werden.

Selfdiagnostic Polymers – Inline Detection of Thermal Degradation of Unsaturated Poly(ester imide)s

Funtan, A., et. al. Advanced Materials, 2021, https://doi.org/10.1002/adma.202100068

Modern electro-engines are based on resins constituted from poly(esterimides) (PEI), isolating and mechanically separating the copper-wires in enamels. We here report a novel, inline-chemical reporting system to monitor thermal degradation of such thermoset-systems by simple solid state fluorescence measurements, thus allowing to prevent short circuits and thus primoridal destruction of the device. © 2021 The Authors. Advanced Materials published by Wiley‐VCH GmbH

Terminal flow of cluster-forming supramolecular polymer networks – single-chain relaxation or micelle reorganization?

Mordvinkin, A., et. al. Phys. Rev. Lett. 2020, 125, 127801, https://journals.aps.org/prl/accepted/6907cYe2G6b10f7bf0d70da94c6a3d21a2892f6e5

We correlate the terminal relaxation of supramolecular polymer networks, based on unentangled telechelic poly(isobutylene) linear chains forming micellar end-group clusters, with the the microscopic chain dynamics as probed by proton NMR. For a series of samples with increasing molecular weight, we find a quantitative agreement between the terminal relaxation times and their activation energies provided by rheology and NMR validating the transient network model and the special case of the sticky Rouse model, and dismissing more dedicated approaches treating the terminal relaxation in terms of micellar rearrangements. Copyright © 2020 by American Physical Society.

The “labile” chemical bond: A perspective on mechanochemistry in polymers.

Binder, W. H. Polymer 2020, 122639, DOI: https://doi.org/10.1016/j.polymer.2020.122639.

Currently noncovalent bonds are ranked equally important to their covalent counterparts, in particular in view of controlling macromolecules structure and assembly by pure force. With Staudinger’s work expanded by mechanically driven bond-rupture in macromolecules, applications of mechanophores are highlighted in view of interfaces, stress-detection, vitrimers and self-healing. Reproduced with permission. Copyright 2020© Elsevier B. V.

Detection of stress in polymers: mechanochemical activation of CuAAC click reactions in poly(urethane) networks.

Biewend, M., et al. Soft Matter 2020, 16 (5), 1137-1141, DOI: http://dx.doi.org/10.1039/C9SM02185J.

We report on copper(i)-bis(N-heterocyclic carbene)s (NHC) for quantitative stress-sensing, embedded within polyurethane networks, triggering a fluorogenic copper(i) azide alkyne cycloaddition (CuAAC) of 8-azido-2-naphtol and 3-hydroxy phenylacetylene. A completely transparent, force responsive poly(urethane) material is generated, allowing a quantification of the applied stress. Reproduced with permission of The Royal Society of Chemistry.

Vitrimers: Associative dynamic covalent adaptive networks in thermoset polymers.

Krishnakumar, B., et al. Chemical Engineering Journal 2020,385, 123820,DOI: https://doi.org/10.1016/j.cej.2019.123820.

The vitrimer-thermoset concept represents an important contribution to improve the durability and recyclability of thermoset-systems. The concept of Associative Dynamic Covalent Adaptive Networks (ADCAN), based on thermosetting vitrimers,demonstrates a high level of stress relaxation, self-healing and shape memory properties. This review article describes the relevant associative dynamic covalent exchange reaction mechanisms for vitrimers within thermosetting polymers and summarizes the resulting material properties with a final focus on recent applications. Reproduced with permission. Copyright 2019© Elsevier B. V.