Bergman cyclization of main-chain enediyne polymers for enhanced DNA cleavage

Cai, Y., et al. Polym. Chem., 2022, DOI:https://doi.org/10.1039/D2PY00259K

Since the discovery of the role of enediynes in natural antibiotics (such as calicheamicines) via in situ diradical-induced DNA strand cleavage, Bergman cyclization has attracted fervent attention for decades. The synthesis of main-chain enediyne polymers was accomplished, allowing to embed and control the reactivity of the diamino enediynes via polycondensation into polyimines inside their main-chain. These polymers exert a chain-length dependent DNA cleavage activity under physiological conditions, additionally tunable by modulating the stereoelectronic environment via their substitution patterns.

Hydrogen-Bonded Supramolecular Polymer Adhesives: Straightforward Synthesis and Strong Substrate Interaction

Chen, S., et al. Angew. Chem. Int. Ed., 2022, DOI:https://doi.org/10.1002/anie.202203876   

High-performance adhesives are important in view of reversible bonding/debonding chemistries, allowing to efficiently recycle and separate polymer blends and composites. We herein identify a straightforward synthetic strategy towards universal hydrogen-bonded (H-bonded) polymeric adhesives, using a side-chain barbiturate (Ba) and Hamilton wedge (HW) functionalized copolymer. Starting from a rubbery copolymer containing thiolactone derivatives, Ba and HW moieties are tethered as pendant groups via an efficient one-pot two-step amine-thiol-bromo conjugation. The presence of individual Ba or HW moieties enables strong binding to a range of substrates, outstanding compared to commercial glues and reported adhesives.

Comparing C2=O and C2=S Barbiturates: Different Hydrogen Bonding Patterns of Thiobarbiturates in Solution and the Solid State

Li, C., et al. Int. J. Macromol. Sci., 2021, DOI:https://www.mdpi.com/1422-0067/22/23/12679

Carbonyl-centered hydrogen bonds with various strength and geometries are often exploited in materials to embed dynamic and adaptive properties, with the use of thiocarbonyl groups as hydrogen-bonding acceptors remaining only scarcely investigated. We herein report a comparative study of C2=O and C2=S barbiturates in view of their differing hydrogen bonds, using the 5,5-disubstituted barbiturate B and the thiobarbiturate TB as model compounds. Differences in their association in solution were extracted via concentration- and temperature-dependent NMR experiments, as well as in Langmuir films, and Brewster angle microscopy. When embedded into a hydrophobic polymer such as polyisobutylene, a largely different rheological behavior was observed for the barbiturate-bearing PB compared to the thiobarbiturate-bearing PTB polymers, indicative of a stronger hydrogen bonding in the thioanalogue PTB.

Hydrogen-Bonds Mediated Nanomedicine: Design, Synthesis and Applications

Chen, S. P., et al. J. Macromol. Rapid Commun., 2022, DOI:https://doi.org/10.1002/marc.202200168

Hydrogen-bonds (H-bonds) bridge artificial and biological sciences, implementing dynamic properties into materials and (macro)molecules, which cannot be achieved via purely covalent bonds. In this review, the current state-of-the-art for designing novel H-bonded nanomedicines for precise diagnosis, and targeted therapeutic drugs delivery are highlighted.

Hydrogen-bonding mediated self-assembly of amphiphilic ABA triblock copolymers into well defined giant vesicles

Wang, H., et al. Polym. Chem., 2021, DOI:https://doi.org/10.1039/D1PY01061A

Giant vesicles represent an extremely useful system to mimic biomembranes. By designing a hydrogen-bonding (H-bonding) amphiphilic ABA triblock copolymer and introducing 2,6-diaminopyridine (DAP) moieties as pendant groups into the middle hydrophobic block, we demonstrate a straightforward and effective self-assembly strategy to form giant vesicles (∼3 μm in diameter) via a combination of H-bonding and amphiphilic interactions. Atomic force microscopy (AFM) studies further prove the hollow interior of these vesicular morphologies. This study provides a new opportunity for the design of supramolecular polymers, serving as polymeric vesicle scaffolds in materials design and may act as red-blood-cell-like containers in delivery and microreactor applications.

Synthesis and self-aggregated nanostructures of hydrogen-bonding polydimethylsiloxane

Chen,* S.,et al. Polymer Chemistry, 2021, 28(12), 4111-4119, https://doi.org/10.1039/D1PY00513H

Gaining control over assembled nanostructures is an important aspect in nanotechnology and materials. We investigate nanostructures, including lamellae (LAM), hexagonally packed cylinders (HPC), body-centered cubic spheres (BCC) and disordered micelles (DIM), primarily influenced by the nature of H-bonding moieties (e.g., Ba, TAP, HW) attached to the PDMS polymers, proving that the immiscibility parameter and volume fraction between nonpolar PDMS and polar H-bonding moieties both are determining the final structures. We report the precise synthesis of tailored polydimethylsiloxanes (PDMS) at their α-ends, bearing a series of H-bonding moieties (e.g., barbiturate (Ba), 2,4,6-triaminopyrimidine (TAP) and Hamilton wedge (HW)), using robust copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Self-aggregated H-bonds are formed in the solid state from the obtained H-bonding PDMS, as evidenced by the temperature dependent solid-state 1H MAS NMR. We also demonstrate a thermally reversible order-disorder transition (ODT) of the observed nanostructures, induced by the H-bonding self-aggregation as observed via temperature-dependent SAXS investigations. Published with a permission of the Royal Society of Chemistry 2021.

Halogen-Bond Mediated 3D Confined Assembly of AB Diblock Copolymer and C Homopolymer Blends

Zheng, X. et al. Small, 2021, 2007570, https://doi.org/10.1002/smll.202007570

Halogen-bond driven assembly, a world parallel to hydrogen-bond, has emerged as an attractive tool for constructing (macro)molecular arrangement. An I….N bond mediated confined-assembly pathway to enable order-order phase transitions is reported here. Polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) AB diblock copolymers are chosen as halogen acceptor, while an iodotetrafluorophenoxy substituted C-type homopolymer, (poly(3-(2,3,5,6-tetrafluoro-4-iodophenoxy)propyl acrylate), PTFIPA) is designed as halogen donor, synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Formation of halogen bonding donor–acceptor pairs induce an order-to-order morphology transition sequence changing from spherical cylindrical lamellar inverse cylindrical. Subsequent selective swelling/deswelling of the P4VP domains gives rise to further internal morphology transitions, creating tailored mesoporous microparticles, disassembled nanodiscs, and superaggregates. © 2021 Wiley‐VCH GmbH

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

Shinde, K.S., et al. Journal of Polymer Science, 2020, 58 (20), 2864-2874, https://doi.org/10.1002/pol.20200404

The incorporation of functional groups into unsaturated polyolefine-polymers often represent a challenging task. We in this paper develop an approach to decorate the polymer backbone of poly(diene)s with ester as well as carboxylic groups via cyclopropanation. Predominantly cis-1,4-poly(isoprene)s are converted with ethyl or tert-butyl diazoacetate using copper(I) N-heterocyclic carbene (NHC) catalysts in modification degrees of 4 – 5 %, displaying potential for up-scaling for manufacturing of modified synthetic rubbers. Copyright 2020©, The Authors. Journal of Polymer Science published by Wiley Periodicals LLC

Engineering the morphology of hydrogen-bonded comb-shaped supramolecular polymers: from solution self-assembly to confined assembly.

Chen, S., et al. Polymer Chemistry 2020 DOI: http://dx.doi.org/10.1039/D0PY00570C.

Herein, comb-shaped hydrophobic supramolecular polymer architectures are constructed trough H-bonding interaction, subsequently challenging the formation of nanostructures under 3D confinement. Benefitting from the weak and dynamic nature of H-bonds, one building block is selectively removed while the other is maintained, affording specific nanostructures, including hollow spheres without resorting to invasive chemical degradation and cleavage. Reproduced by permission of The Royal Society of Chemistry.

„Honig“ bis „Gummi“: Die variablen Eigenschaften des Polyisobutylen. 100 Jahre Makromolekulare Chemie.

Binder, W. H., Faszination Chemie, die Informationsplattform der GDCh 2020 https://faszinationchemie.de/makromolekulare-chemie/news/honig-bis-gummi-die-variablen-eigenschaften-des-polyisobutylen-1/

Als Polyisobutylen (PIB) erstmals durch Polymerisation von Isobuten (IB) mittels Schwefelsäure hergestellt wurde, hatte der Polymerchemiker Hermann Staudinger noch acht Jahre Zeit, das Licht der Welt zu erblicken. Die uns heute vertraute (molekulare) Kettenstruktur des PIBs war damals noch unbekannt, ebenso wie sein technischer Nutzen. Seine Eigenschaften kann der Chemiker* variabel einstellen und so dient es für unterschiedliche Anwendungen: ob „kulinarisch erlebbar“ für Kaugummis, als Butylkautschuk oder in der Medizin. Reproduced with permission. Copyright athee23/pixabay.com