Synthesis and self-aggregated nanostructures of hydrogen-bonding polydimethylsiloxane

Chen,* S.et al. Polymer Chemistry, 2021, ASAP, 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

Nitrogen-doped graphene stabilized copper nanoparticles for Huisgen [3+2] cycloaddition “click” chemistry.

Siva Prasanna Sanka, R. V., et al. Chemical Communications 2019, 55 (44), 6249-6252, DOI: http://dx.doi.org/10.1039/C9CC02057H.

Nitrogen-doped reduced graphene oxide (NRGO) stabilized copper nanoparticles are designed to assist Cu(i)-catalyzed Huisgen [3+2] cycloaddition “click” chemistry (CuAAC). The CuAAC at low temperature without any external additive (oxidizing/reducing agent) with high stability and recyclability is achieved. Reproduced by permission of The Royal Society of Chemistry.

The CuAAC: Principles, Homogeneous and Heterogeneous Catalysts, and Novel Developments and Applications.

Neumann, S., et al. Macromolecular Rapid Communications 2019, 1900359, DOI: https://doi.org/10.1002/marc.201900359.

The copper-catalyzed azide/alkyne cycloaddition reaction (CuAAC) has emerged as the most useful ?click? chemistry. Polymer science has profited enormously from CuAAC by its simplicity, ease, scope, applicability and efficiency. The CuAAC with a focus on homogeneous and heterogeneous catalysts, ligands, anchimeric assistance, and basic chemical principles, ligand design and acceleration are discussed. Reproduced by permission of WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of Ring Expansion-Controlled Radical Polymerization System by AFM Observation.

Narumi, A., et al. ACS Macro Letters 2019, 8 (6), 634-638, DOI: https://doi.org/10.1021/acsmacrolett.9b00308.

We here present a direct link between the reaction mechanisms for the ring-expansion “vinyl” polymerization system and atomic force microscopy (AFM) observations. The relationship between the molecular chain lengths and the cyclic versus linear morphologies is highlighted. Reproduced with permission. Copyright 2019©, American Chemical Society.

Synthesis and Aggregation of Polymer-Amyloid β Conjugates.

Evgrafova, Z., et al. Macromolecular Rapid Communications 2019, 1900378, DOI: https://doi.org/10.1002/marc.201900378.

The synthesis of polymer-peptide conjugates composed of the amyloidogenic Alzheimer peptide, Aβ1-40, and poly(oligo(ethylene glycol)m acrylates) (m = 2,3) with different molecular weights (Mn = 1400-6600 g mol-1) is presented. Aggregation of these Aβ1-40 conjugates is accelerated upon attaching the polymer. Reproduced with permission. Copyright 2019©, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CuAAC-Based Click Chemistry in Self-Healing Polymers.

Döhler, D., et al. Accounts of Chemical Research 2017, 50 (10), 2610-2620, DOI: http://dx.doi.org/10.1021/acs.accounts.7b00371.

Click chemistry has emerged as a significant tool for materials science, organic chemistry, and bioscience. The use of the CuAAC in self-healing systems, most of all the careful design of copper-based catalysts linked to additives as well as the chemical diversity of substrates, has led to an enormous potential of applications of this singular reaction. The examples reported here describe chemical concepts to realize more efficient and faster click reactions in self-healing polymeric materials, via enhanced chain diffusion in (hyper)branched polymers, autocatalysis, or internal chelation concepts enable efficient click cross-linking already at 5 °C. We have designed special CuAAC click methods for chemical reporting and visualization systems based on the detection of ruptured capsules via a fluorogenic click reaction and we have prepared polymeric Cu(I)–biscarbene complexes to detect (mechanical) stress within self-healing polymeric materials via a triggered fluorogenic reaction, thus using a destructive force for a constructive chemical response. Reproduced with permission. Copyright 2017©, American Chemical Society.