Research Field 2

Li, C. et. al., Chem. Europ. J., 2025,  31, 8,e202403939, https://doi.org/10.1002/chem.202403939

The molecular environment around supramolecular bonding systems significantly affects their stability and the assembly of host–guest complexes, most prominent for hydrogen bonds (H-bonds). We here investigate the formation of higher order assemblies of hydrogen bonds, using the Hamilton receptor-barbiturate host–guest complexes as a model system. A novel Hamilton receptor (H) was equipped with cyclopentene moieties and used as a host to form host–guest complexes (H−B) with allobarbital (B), followed by covalent crosslinking. Higher-order aggregates (HH-dimer, HHH-trimer) were subsequently detected via an alkene cross-metathesis (CM) reaction to fix the assemblies covalently, followed by analysis via electrospray ionization mass spectrometry (ESI MS). This two-step method, firstly via CM fixation followed by ESI MS, was extended to study the H−B model complex within a polyisobutylene (PIB) matrix, presenting a direct method to analyze the complex host–guest assembly in solvent-free (polymer) environments. © 2024 The Author(s). Chemistry – A European Journal published by Wiley-VCH GmbH. Open access

Karle, M. et. al.; Polym. Sci. Technol., 2025,  https://pubs.acs.org/doi/10.1021/polymscitech.5c00118

We here report latent catalysts for a thermally triggered transesterification in polyester vitrimers, enabling a triggered dynamic bond exchange using N-heterocyclic carbenes (NHC–CO₂) and the organic amine salts, triazabicyclo[4.4.0]dec-5-ene (TBD) methanesulfonic acid (MSA), TBD:MSA. These catalysts are inactive under service conditions but active at elevated temperature or shear enable reversible covalent bond exchange. Mechanical testing after repeated cycling of the vitrimer confirmed that both pristine (E = 0.03 MPa) and reprocessed (E = 0.11 MPa) samples retained tensile properties so demonstrating efficient recyclability.

Singh, P. et. al. ACS Applied Materials & Interfaces, 2024, 16, 40, 54693–54705, https://doi.org/10.1021/acsami.4c13361

A versatile and robust end-group derivatization approach Microwave-stimulated smart self-healable polymeric coatings with significant protective technology against corrosion have been developed in this work. Herein, a generous approach is strategized to generate linseed oil-derived epoxy composites embedded with reduced graphene oxide (rGO) as a nanofiller in the shielding network. The composite showed excellent self-healing and shape memory properties when irradiated with microwaves due to the dynamic reversible nature of the disulfide covalent bond exchange mechanism. The network also has improved thermomechanical properties and thermal stability, with a storage modulus of 20.8 GPa and a low activation energy of 79 kJ/mol, indicating a fast disulfide dynamic exchange reaction. The amine functionality in the composite contributes to excellent corrosion protection, with 99.9% protection efficiency, as validated via a Tafel plot. The composite also showed excellent hydrophobicity, with a 131° contact angle. This study provides insights into the engineering and application of smart materials as anticorrosive coatings. Copyright © 2024 American Chemical Society.

Adjedje, V. K. B. et. al. Macromolecular Rapid Communications, 2024, 45, 11, 2400032, https://doi.org/10.1002/marc.202400032

A versatile and robust end-group derivatization approach using oximes has been developed for the detection of oxidative degradation of synthetic polyisoprenes and polybutadiene. This method demonstrates broad applicability, effectively monitoring degradation across a wide molecular weight range through ultraviolet (UV)-detection coupled to gel permeation chromatography. Importantly, it enables the effective monitoring of degradation via derivatization-induced UV-maximum shifts, even in the presence of an excess of undegraded polyene, overcoming limitations previously reported with refractive index detectors. © 2024 The Authors. Macromolecular Rapid Communications published by Wiley‐VCH GmbH.

Shinde, K.S. et.al., Macromol. Chem. Phys., 2023, 2300297, https://doi.org/10.1002/macp.202300297

Here, a mechanochemically triggered Cu(I) bis(N-heterocyclic carbene [NHC))-based metal–organic framwork (MOF) embedded into a thermoplastic polyurethane (TPU)-matrix is reported. The induced fluorogenic copper-catalyzed azide–alkyne cycloaddition (CuAAC) reveals the stressed parts within the thermoplastic PU via a simple optical detection. As determined via oscillating tensile rheology on dumbbell-shaped samples of TPU, a MOF, containing 4.66% copper, catalyzes the fluorogenic CuAAC between the nonfluorescent precursor dyes, 8-azidonaphthalen-2-ol, and 3-hydroxyphenylacetylene. After mechanical activation of the MOF situated inside the TPU, the fluorescent 8-(4-(3-hydroxyphenyl)-1,2,3-triazol-1-yl)naphthalen-2-ol dye is formed. Monitoring the formation of the dye inside the TPU via fluorescence spectrometry at λ_ex = 458 nm shows an increase of the fluorescence intensity up to 60–70%. It is demonstrated that a dumbbell-shaped TPU, subjected to higher stress, displays higher fluorescence than the surrounding other areas, thus effectively functioning as a three-in-one stress-sensor system.

Ucak, Ö. et al., Macromolecular Chemistry and Physics, 2022, 2200344,

https://doi.org/10.1002/macp.202200344

The synthesis of well-defined homo- and co-polypeptides of L-alanine (L-Ala) by ring-opening polymerization (ROP) of its N-carboxyanhydride (NCAs), either via suspension/interfacial- or solution phase-polymerization using 10-undecene-1-amine and α,ω-diamino poly(ethylene glycol) (8 or 1.5 kDa) as primary amine initiators is reported. Subsequently, the folding of the homo- and triblock amphiphilic co-polypeptides under a variety of parameters such as temperature, chain length, and backbone composition and the further transitions of these secondary structures are investigated in HFIP and HFIP-H₂O mixtures via circular dichroism (CD) spectroscopy. A solvent induced helical switch from a 3₁₀-helix to a α-helix when changing from HFIP to HFIP–water mixtures is observed, with water inducing helicity stronger in both, homo-polyalanine and poly(alanine)-PEG-poly(alanine) triblock copolymers. © 2022 The Authors. Macromolecular Chemistry and Physics published by Wiley‐VCH GmbH.

Siva Prasanna Sanka, R. V. et al., Soft Matter, 2023, 98-105,

https://doi.org/10.1039/D2SM01423H

N-doped graphene stabilized Cu(I)-catalyzed self-healing nanocomposites are developed, demonstrating the use of N-doped graphene as both a nanostructured material for enhancing mechanical and conductive properties to trigger self-healing via “click chemistry”. Due to an increase in electron density on nitrogen atom doping, including the coordination of N-doped rGO with Cu⁺ ions, nitrogen-doped graphene-supported copper particles demonstrate a higher reaction yield at room temperature without adding any external ligand/base. Tensile measurements were also performed using molecular dynamics (MD) simulations to support the findings. Given the enormous importance of autonomic repair of materials damage, this concept here reports a trustworthy and reliable chemical system with a high level of robustness. Published with a permission of the Royal Society of Chemistry 2023.

Sharma, H. et al., RSC Advances, 2022, 32569-32582,

http://dx.doi.org/10.1039/D2RA05103F

To achieve sustainable development goals, approaches towards the preparation of recyclable and healable polymeric materials is highly attractive. Self-healing polymers and thermosets based on bond-exchangeable dynamic covalent bonds, so called “vitrimers” could be a great effort in this direction. In order to match the industrial importance, enhancement of mechanical strength without sacrificing the bond exchange capability is a challenging issue, however, such concerns can be overcome through the developments of fiber-reinforced vitrimer composites. This article covers the outstanding features of fiber-reinforced vitrimer composites, including their reprocessing, recycling and self-healing properties, together with practical applications and future perspectives of this unique class of materials. Published with a permission of the Royal Society of Chemistry 2022.

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.

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.