Research Field 1

Michael, P. et. al., Polymer, 2025, 335, 128816, https://doi.org/10.1016/j.polymer.2025.128816

We report a polymeric mechanocatalyst based on polymeric Cu(I)-biscarbene complexes (Mn = 4750; 8900; 17200 g mol−1) and its mechanochemical decomposition by ultrasound. Distinct decomposition pathways are observed via either purely thermal activation or mechanochemical activation. A lowering of the mechanochemical activation energy is observed in comparison to the purely thermal activation pathway. Quantum chemical calculations and experimental investigations support that splitting one carbene residue from a biscarbene-Cu(I)-center is favored mechanochemically. © 2025 The Authors. Published by Elsevier Ltd. Open access

Canalp, M. B. et. al.; Macromolecular Chemistry and Physics, 2025, 2400510, 226, 11,https://doi.org/10.1002/macp.202400510

Advancing novel polymers for biomedical applications requires in-depth knowledge between their chemical structure and physical properties under conditions such as assembly or folding. Weh ave prepared hybrid-polymers containing lysine-residues (Lys) inside their main chain, separated by a stretch of n-alkyl-chains, (A-[Lys_{n = 1}]_{m = 18}) y ADMET polymerization of the bis-ω-ene-functional mono-L-lysine(Z)s (Lys_{n = 1}). The hybrid-polymers, A-[Lys_{n = 1}]_{m = 3, 7, 9, 18, 44} with molecular weights ranging from 1.3 to 17.6 kDa, display polydispersity (Đ) values in the range of 1.3–2.6. Comparison between these polymers and previously reported hybrid ADMET polymer proved the presence of α-helices and β-folds at elevated temperatures in the range of 20 to 200 °C. © 2025 The Author(s). Macromolecular Chemistry and Physics published by Wiley‐VCH GmbH. Open access

Rummel, F. et. al., Macromolecules, 2025,  58, 5, 2366–2378, https://doi.org/10.1021/acs.macromol.4c03132

A ruthenium-catalyzed hydrogen transfer ester metathesis (HTEM) is reported that allows for the isomerization of different types of linear polyesters such as polylactones without the need for any stoichiometric reagent, forming novel types of copolyesters containing additional alkylene dicarboxylate (AD) repeating units. Poly(butylene succinate) (PBS) is depolymerized to cyclic butyrolactone (BL_c) with high yield and high selectivity, whereas cyclic valero- (VL_c) and caprolactone (CL_c) can be polymerized by HTEM to poly(lactone-alkylene dicarboxylate) copolyesters. Mechanistic investigations show that the formation of the chemically modified polyester relies on a two-fold catalytic reaction: a HTEM via a hydrogen borrowing process and a concomitant transesterification catalyzed by the base cocatalyst. Copyright © 2025 The Authors. Published by American Chemical Society. Open access

Gloger, D. et. al. ACS Applied Polymer Materials, 2024, 6, 10824-10841, https://doi.org/10.1021/acsapm.4c01938

In this study, we report the coupling of high-density polyethylene (HDPE) and isotactic polypropylene (iPP) into grafted block copolymers (HDPE-g-iPP) from HDPE and iPP precursors subjected to reactive extrusion with an organic peroxide, however, without a cross-linker. Coupling of macroradicals in the melt state is confined to a small interfacial volume at the HDPE/iPP domain interfaces of this immiscible two-phase blend system. The tendency of HDPE macroradicals to branch and cross-link into a solid-like network, together with the tendency of iPP macroradicals to simply cleave, is a common problem to overcome. Moreover, to prove HDPE-g-iPP molecules in reactive HDPE/iPP blends is difficult due to the low grafting yields and the additional challenge to analytically distinguish HDPE-g-iPP molecules from the HDPE/iPP matrix. In this study, we work with a low-viscosity blend system, which, combined with the low unsaturation content of the HDPE, made cross-linking negligible. We identify HDPE-g-iPP molecules via interaction chromatography by iPP components in the HDPE elution range and by analytical temperature-rising elution fractionation, where we find HDPE in the iPP elution range. Physical characterization by thermal, dynamic mechanical, and morphological analyses confirmed that the reactive blend is compatibilized by HDPE-g-iPP molecules, seen by shifts in crystallization temperature and glass transition, and by diffuse domain interfaces. With improved grafting yields, reactive blends could potentially be used directly as compatibilizers. Copyright © 2024, American Chemical Society.

Cai, Y. et. al. Macromolular Chemistry & Physics, 2024, 2400177, https://doi.org/10.1002/macp.202400177

Semi-interpenetrating polymer networks (semi-IPNs), composed of two or more polymers, forming intertwined network-architectures, represent a significant type of polymer combination in modern industry, especially in automotive and medical devices. An initiator-free synthesis of semi-interpenetrating polymer networks via Bergman cyclization (BC) is reported here, acting as a trigger to embed a second polymer via its reactive enediyne (EDY) moiety, then embedded into the first network. (Z)-oct-4-ene-2,6-diyne-1,8-diol (diol-EDY) is targeted as the precursor of the second polymer, swollen into the first polyurethane network (PU), followed by a radical polymerization induced by the radicals formed by the BC. The formation of the semi-IPN is monitored via electron paramagnetic resonance (EPR) spectroscopy, infrared-spectroscopy (FT-IR), and thermal methods (DSC), proving the activation of the EDY-moiety and its subsequent polymerization to form the second polymer. Stress−strain characterization and cyclic stress−strain investigations, together with TGA and DTG analysis, illustrate improved mechanical properties and thermal stability of the formed semi-IPN compared to the initial PU-network. The method presented here is a novel and broadly applicable approach to generate semi-IPNs, triggered by the EDY-activation via Bergman cyclization. © 2024 The Author(s). Macromolecular Chemistry and Physics published by Wiley‐VCH GmbH.

Alqaisi, M. et. al., Polymer Chemistry, 2024, 15, 2949 – 2958, https://doi.org/10.1039/D4PY00355A

The generation of nanosized compartments in single chain nanoparticles (SCNPs) is a promising approach to generate individualized confinement-zones on a small scale for drug-encapsulation or catalysis. We here report the synthesis and characterization of compartmented, fluorinated SCNPs generated by single-chain collapse of amphiphilic copolymers. Polyethylene glycol (PEG) functionalized monomers were utilized as hydrophilic moieties, while hydrophobic residues were introduced using different mole fractions of either aliphatic or fluorinated monomers. Single chain collapse and subsequently crosslinking via copper-catalyzed azide–alkyne click reactions in selective and non-selective solvents yields internally structured SCNPs with hydrodynamic radii of 2.5–5.8 nm. Reproduced with permission from the Royal Society of Chemistry

Cai, Y. et.al., Macromol. Rapid Commun., 2023, 202300440,  https://doi.org/10.1002/marc.202300440

Crosslinking chemistries occupy an important position in polymer modification with a particular importance when triggered in response to external stimuli. Enediyne (EDY) moieties are used as functional entities in this work, known to undergo a pericyclic Bergman cyclization (BC) to induce a triggered crosslinking of polyurethanes (PU) via the intermediately formed diradicals. Diamino-EDYs, where the distance between the enyne-moieties is known to be critical to induce a BC, are placed repetitively as main-chain structural elements in isophorone-based PUs to induce reinforcement upon heating, compression, or stretching. A 7-day compression under room temperature results in a ≈69% activation of the BC, together with the observation of an increase in tensile strength by 62% after 25 stretching cycles. Purely heat-induced crosslinking contributes to 191% of the maximum tensile strength in comparison to the virgin PU. The BC herein forms an excellent crosslinking strategy, triggered by heat or force in PU materials. © 2023 The Authors. Macromolecular Rapid Communications published by Wiley‐VCH GmbH

Li, C. et. al., Macromol. Raid Commun., 2023,  2300464,  https://doi.org/10.1002/marc.202300464 

Hydrogen bonds (H-bonds) are highly sensitive to the surrounding environments owing to their dipolar nature, with polar solvents kown to significantly weaken H-bonds. Herein, the stability of the H-bonding motif ureidopyrimidinone (UPy) is investigated, embedded into a highly polar polymeric ionic liquid (PIL) consisting of pendant pyrrolidinium bis(trifluoromethylsulfonyl)imide (IL) moieties, to study the influence of such ionic environments on the UPy H-bonds. The content of the surrounding IL is changed by addition of an additional low molecular weight IL to further boost the IL content around the UPy moieties in molar ratios of UPy/IL ranging from 1/4 up to 1/113, thereby promoting the polar microenvironment around the UPy-H-bonds. Variable-temperature solid-state MAS NMR spectroscopy and FT-IR spectroscopy demonstrate that the UPy H-bonds are largely present as (UPy-) dimers, but sensitive to elevated temperatures (>70 °C). Subsequent rheology and DSC studies reveal that the ILs only solvate the polymeric chains but do not interfere with the UPy-dimer H-bonds, thus accounting for their high stability and applicability in many material systems. © 2023 The Authors. Macromolecular Rapid Communications published by Wiley‐VCH GmbH