Research Field 2

Sammon, M. S., et al. Chem Eur. J., 2021, DOI:https://doi.org/10.1002/chem.202100555 and https://doi.org/10.1002/chem.202101683

Point break: A latent copper-biscarbene mechanocatalyst becomes active when a ligand is forcefully removed. Pulling with around 2 nN breaks the copper-carbon bond, as measured by single-molecule force spectroscopy. To be able to assign the bond rupture event to the Cu−C bond, mechanophores with two different lengths of safety-line were specifically synthesized for use in this AFM experiment.

Rupp, H., et al. Macromol. Rapid. Commun., 2021, DOI:https://doi.org/10.1002/marc.202000450

The preparation and characterization of mechanoresponsive, 3D-printed composites are reported using a dual-printing setup for both, liquid dispensing and fused-deposition-modeling. The here reported stress-sensing materials are based on high- and low molecular weight mechanophores, including poly(ε-caprolactone)-, polyurethane-, and alkyl(C11)-based latent copper(I)bis(N-heterocyclic carbenes), which can be activated by compression to trigger a fluorogenic, copper(I)-catalyzed azide/alkyne “click”-reaction of an azide-functionalized fluorescent dye inside a bulk polymeric material. The multicomponent specimen containing both, azide and alkyne, are manufactured via a 3D-printer to place the components separately inside the specimen into void spaces generated during the FDM-process, which subsequently are filled with liquids using a separate liquid dispenser, located within the same 3D-printing system, finally yielding a mechanoresponsive material.

Döhler, D., et al. ACS Appl. Polym. Mater., 2020, DOI:https://dx.doi.org/10.1021/acsapm.0c00755

We present a comprehensive investigation of mechanical properties of supramolecular polymer networks with rationally developed multistrength hydrogen-bonding interactions to embed self-healing properties into poly(dimethylsiloxane) (PDMS)-based elastomers. By changing the ratio between isophorone diisocyanate (IU), 4,4′-methylenebis(cyclohexyl isocyanate) (MCU), and 4,4′-methylenebis(phenyl isocyanate) (MPU) and by varying the molecular weight of the PDMS precursor, we obtained a library of poly(urea)s to study the interplay of mechanical performance and self-healability. We achieved an optimum balance between mechanical properties and self-healing performance, and by the additional reduction of the molecular weight of the precursor polymer, a minimum recovery of 80% in stress within 12 h at room temperature was observed. Selected poly(urea)s could be processed via 3D printing by the conventional extrusion method, obtaining dimensionally stable and freestanding objects.

Shinde, K., et al. J. Polym. Sci., 2020, DOI:https://doi.org/10.1002/pol.20200404

The incorporation of functional groups into unsaturated polyolefine-polymers often represent a challenging task, in particular in synthetic rubber such as poly(isoprenes). Based on the cyclopropanation of double bonds with diazoesters in the presence of metal-catalysts we in this article develop an approach to decorate the polymer backbone of poly(diene)s with esters and carboxylic acids, reaching modification degrees of up to 17%. The resulting esters were further converted to the corresponding free carboxylic groups by deprotection using trifluoroacetic acid

Raimondo*, M., et. al. Polymers, 2021, 13(9), 1401, https://www.mdpi.com/2073-4360/13/9/1401

A big step forward for composite application in the sector of structural materials is given by the use of Multi-Wall Carbon Nanotubes (MWCNTs) functionalized with hydrogen bonding moieties, such as barbiturate and thymine, to activate self-healing mechanisms and integrate additional functionalities. We report the characterization of rubber-toughened supramolecular self-healing epoxy formulations based on unfunctionalized and functionalized MWCNTs using Tunneling Atomic Force Microscopy (TUNA). TUNA proved to be very effective for the morphology study of both the unfunctionalized and functionalized carbon nanotube-based conductive networks, thus providing useful insights aimed at understanding the influence of the intrinsic nature of the nanocharge on the final properties of the multifunctional composites. © This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.

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/
https://www.youtube.com/watch?v=GNYnRDEJQy8

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).

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.

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 Lcp_K30. Published with a permission of the Green Chemistry 2021.