Synthesis and Characterization of Quadrupolar-Hydrogen-Bonded Polymeric Ionic Liquids for Self-Healing Electrolytes

Chenming Li , et al. Polymers, 2022, 14, 4090, DOI: https://doi.org/10.3390/polym14194090

Within the era of battery technology, the urgent demand for improved and safer electrolytes is immanent. In this work, novel electrolytes, based on pyrrolidinium-bistrifluoromethanesulfonyl-imide polymeric ionic liquids (POILs), equipped with quadrupolar hydrogen-bonding moieties of ureido-pyrimidinone (UPy) to mediate self-healing properties are generated. The polymers display good conductivities as well as a self-healing efficiency of up to 88 %, in turn evidencing a rational design of self-healing electrolytes bearing, both hydrogen bonding moieties and low-molecular-weight polymeric ionic liquids.

Design, synthesis and characterization of vitrimers with low topology freezing transition temperature

Krishnan, B. P., et al. Polymers, 2022, DOI:https://doi.org/10.3390/polym14122456

Vitrimers are crosslinked polymeric materials that behave like fluids when heated, regulated by the kinetics of internal covalent bond-exchange, making these materials readily reprocessable and recyclable. We report two novel multiphase vitrimeric materials prepared by the cross-linking of two polymers, namely poly(triethylene glycol sebacate) and poly(2-hydroxyethyl acrylate), using zinc acetate or tin(II) 2-ethylhexanoate as catalysts, which exhibit significantly low Tv temperatures of 39 °C and 29 °C, respectively. The design of such multiphase vitrimers is not only useful for the practical application of vitrimers to reduce plastic waste but could also facilitate further development of functional polymer materials that can be reprocessed at low temperatures.

Kunststofftechnik: Thermischen Abbau erkennen

Binder, W. H., et al. Nachrichten aus der Chemie., 2022, DOI:https://doi.org/10.1002/nadc.20224120686   

Während des Betriebes von Elektromotoren führen thermischen Alterungsprozesses in den PEI-Imprägnierungen zur Freisetzung von als Hauptabbauprodukte, die als nucleophile Analyten für trifluoroacetyl funktionalisierte Stilbene fungieren. Es wurde ein optisches Inline-Detektionssystem entwickelt, um zukünftig unnötige Motorenwechsel zu verhindern und, mit Blick auf die zunehmende Elektromobilität, einen wertvollen Beitrag zur Nachhaltigkeit zu leisten.

A Mechanochemically Active Metal-Organic Framework (MOF) Based on Cu-Bis-NHC-Linkers: Synthesis and Mechano-Catalytic Activation

Shinde, K., et al. Polymers, 2022, DOI:https://doi.org/10.1002/macp.202200207

Porous coordination polymers, more commonly known as metal-organic frameworks (MOFs), are constructed from metal ions and organic linkers which form a robust network-like structure similar to very dense polymeric networks. We report on the mechanochemical activation of a MOF linking a mechanochemically triggered copper-catalyzed azide-alkyne cycloaddition (CuAAC) with an NHC-MOF. A Cu(I) bis(NHC) is embedded into the MOF analogous to ([Zn4O{Cu(L)2}2]) using the organic bis-NHC ligand, in turn triggering a CuAAC with conversions up to 26.5%. With this knowledge in solution, there are prospects to transfer this mechanochemical activity into polymer networks with embedded MOFs to detect stress in hybrid materials.

Activation of a Copper Biscarbene Mechano-Catalyst Using Single-Molecule Force Spectroscopy Supported by Quantum Chemical Calculations

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.

Functional structural nanocomposites with integrated self-healing ability

Guadagno, l., et al. Materials Today: Proceedings, 2021, DOI:https://www.sciencedirect.com/science/article/pii/S2214785320318253

The use of aeronautical thermosetting resins in the field of structural materials is still limited because of several drawbacks, such as the absence of electrical and thermal conductivity and the poor impact damage resistance. An important contribution for increasing the composite application in this field can be given by implementing a strategy of autonomous damage-repair and other specific functions integrated into the material structure. This work proposes a successful strategy based on the design of supramolecular self-healing systems. It is aimed at developing self-healing, load-bearing structures with all functionalities integrated into a single material able to fulfill important industrial requirements.

Multicomponent stress-sensing materials fabricated by 3D-printing-methodologies

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.

Tuning the Self-Healing Response of Poly(dimethylsiloxane)-Based Elastomers

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.

Cyclopropanation of Poly(isoprene) Using NHC-Cu(I) Catalysts: Introducing Carboxyltes

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

Tunneling Atomic Force Microscopy analysis of supramolecularself-responsive nanocomposite

Raimondo*, M., et. al. Polymers, 2021, 13(9), 1401https://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.