Halo‐ester‐functionalized poly(ethylene glycol)s (PEGs) are successfully prepared by the transesterification of alkyl halo‐esters with PEGs using Candida antarctica lipase B (CALB) as a biocatalyst under the solventless conditions. Transesterifications of chlorine, bromine, and iodine esters with tetraethylene glycol monobenzyl ether (BzTEG) are quantitative in less than 2.5 h. The transesterification of halo‐esters with PEGs are complete in 4 h. 1H and 13C NMR spectroscopy with MALDI‐ToF and ESI mass spectrometry confirm the structure and purity of the products. This method provides a convenient and “green” process to effectively produce halo‐ester PEGs.
A linear supramolecular polymer based on the self‐assembly of an easily available copillar[5]arene monomer is efficiently prepared, which is evidenced by the NMR spectroscopy, viscosity measurement, and DOSY experiment. The single‐crystal X‐ray analysis reveals that the polymerization of the AB‐type monomer is driven by the quadruple CH•••π interactions and one CH•••O interaction.
A recent response on a publication from our team investigating solvent effects on propagation rate coefficients is commented. Among other issues, we point to the fact that the response interprets only a subset of the data provided in our original contribution.
We report the functionalization of polypyrrole (PPy) with a “sticky” biomolecule dopamine (DA), which mimics the essential component of mussel adhesive protein. PPy is one of the most promising electrically conductive polymers with good biocompatibility. The research findings reveal that the DA functionalization enhances the dispersibility and stability of PPy in water and its film adhesion to substrate surface significantly. The electrical conductivity of PPy increases to a maximum value and then decreases with the increasing DA concentration. An optimal DA to pyrrole (Py) mole ratio is found to be between 0.1 and 0.2, at which both conductivity and adhesion of DA‐functionalized PPy has been improved.
The termination mechanism of the radical polymerization of acrylates, namely the selectivity of disproportionation (Disp) and combination (Comb) between polymer end radicals, is unambiguously determined by the reaction of polyacrylate end radicals generated from corresponding “living” organotellurium ω‐end polymer. While textbooks describe the occurrence of Comb, the reaction at 25 °C exclusively gives the Disp products. Ab initio molecular dynamics suggests that the products form by two pathways: The direct disproportionation reaction and a novel stepwise process that involves the initial formation of the C–O coupling product followed by intramolecular rearrangement. The termination at high temperature and low radical concentration increases the contribution of back‐biting reaction giving mid‐chain radicals, and complex reaction pathways of the mid‐chain radicals are clarified for the first time.
The preparation of multifunctional polymers and block copolymers by a straightforward one‐pot reaction process that combines enzymatic transacylation with light‐controlled polymerization is described. Functional methacrylate monomers are synthesized by enzymatic transacylation and used in situ for light‐controlled polymerization, leading to multifunctional methacrylate‐based polymers with well‐defined microstructure.
Multivalent binding is a key for many critical biological processes and unique recognition and specificity in binding enables many of different glycans and proteins to work in a great harmony within the human body. In this study, the binding kinetics of synthetic glycopolypeptides to the dendritic cell lectin DC‐SIGN and their inhibition potential for DC‐SIGN interactions with the gp120 envelope glycoprotein of HIV‐1 (gp120) are investigated.
A new method for fabricating hydrogels with intricate control over hierarchical 3D porosity using microfiber porogens is presented. Melt electrospinning writing of poly(ε‐caprolactone) is used to create the sacrificial template leading to hierarchical structuring consisting of pores inside the denser poly(2‐oxazoline) hydrogel mesh. This versatile approach provides new opportunities to create well‐defined multilevel control over interconnected pores with diameters in the lower micrometer range inside hydrogels with potential applications as cell scaffolds with tunable diffusion and transport of, e.g., nutrients, growth factors or therapeutics.
A new class of colloidal polymeric particles consisting of polystyrene spheres grown in a poly(N‐isopropyl acrylamide) precursor scaffold is synthesized via redox‐initiated heterophase polymerization. The morphology and thermoresponsiveness of these assemblies is proven by electron microscopy investigations and temperature‐dependent measurements of the change of both the speed of sound travelling through the dispersion and the hydrodynamic particle size. Electron microscopy (EM) micrographs (transmission and scanning EM as well cryo‐scanning EM) prove the existence of colloidal clusters when the freeze‐dried copolymer is redispersed in pure water. The clusters have a size of several micrometers, contain about 800 polystyrene particles with diameter below 100 nm, and show a highly reproducible thermoresponsive behavior with a lower critical solution temperature corresponding to that of pure poly(N‐isopropyl acrylamide).
Using the third‐generation Grubbs catalyst, the living ring‐opening metathesis polymerization of ferrocene/cobalticenium copolymers is conducted with theoretical numbers of 25 monomer units for each block, and their redox and electrochemical properties allow using the Bard–Anson electrochemical method to determine the number of metallocenyl units in each block.
A heterotritopic copillar[5]arene monomer by introducing effective neutral guest moieties (methylene chains end‐capped with cyano and triazole groups) to a pillar[5]arene macrocycle is prepared. This well‐designed AB2‐type copillar[5]arene contains strong host–guest recognition motifs that are connected with relatively flexible and long linkers, thus efficiently assembles to form supramolecular hyperbranched polymer (SHP) in chloroform solution, which is characterized by various techniques including 1H NMR, DOSY, viscosity, DLS, and TEM. Particularly, this supramolecular polymer can be effectively depolymerized by adding a competitive butanedinitrile guest.
The functionalization of zinc oxide (ZnO) nanoparticles by poly(3‐hexylthiophene) (P3HT) brush is completed by the combination of a mussel inspired biomimetic anchoring group and Huisgen cyclo‐addition “click chemistry.” Herein, the direct coupling of an azide modified catechol derivative with an alkyne end‐functionalized P3HT is described. This macromolecular binding agent is used to access core@corona ZnO@P3HT with a stable and homogeneous conjugated organic corona. Preliminary photoluminescence measurement proves an efficient electron transfer from the donor P3HT to the acceptor ZnO nanoparticles upon grafting, thus demonstrating the potential of such a combination in organic electronics.
Here, a novel method is demonstrated for the preparation of three‐arm branched microporous organic nanotube networks (TAB‐MONNs) based on molecular templating of three‐arm branched core–shell bottlebrush copolymers and Friedel–Crafts alkylation reaction. The unique three‐arm branched bottlebrush copolymers are synthesized by a combination of atom transfer radical polymerization, reversible addition‐fragmentation chain transfer polymerization, and ring‐opening polymerization techniques. In this approach, the length and diameter of branched tube units can be well‐controlled by rational molecular design. Moreover, the as‐prepared TAB‐MONNs possess a high surface area and exhibit a superior adsorption capacity for Rhodamine 6G (R6G) and p‐cresol.
Cationic imidazolium‐functionalized polyethylene is accessible by insertion copolymerization of ethylene and allyl imidazolium tetrafluoroborate (AIm‐BF4) with phosphinesulfonato palladium(II) catalyst precursors. Imidazolium‐substituted repeat units are incorporated into the main chain and the initiating saturated chain end of the linear polymers, rather than the terminating unsaturated chain end. The counterion of the allyl imidazolium monomer is decisive, with the chloride analogue (AIm‐Cl) no polymerization is observed. Stoichiometric studies reveal the formation of an inactive chloride complex from the catalyst precursor. An effect of moderate densities (0.5 mol%) of ionic groups on the copolymers' physical properties is exemplified by an enhanced wetting by water.
Diarylbutadiyne derivatives are ideal monomers for providing the π‐electron‐conjugated system of polydiacetylenes (PDAs). The geometrical parameters for diacetylene topochemical polymerization are known. However, control of the molecules under these parameters is yet to be addressed. This work shows that by simply tailoring diarylbutadiyne with amide side‐chain substituents, the arrangement of the substituents and the resulting hydrogen bond framework allows formation of π‐electron‐conjugated PDA.
The chemical control of cell division has attracted much attention in the areas of single cell‐based biology and high‐throughput screening platforms. A mussel‐inspired cytocompatible encapsulation method for achieving a “cell‐division control” with cross‐linked layer‐by‐layer (LbL) shells is developed. Catechol‐grafted polyethyleneimine and hyaluronic acid are chosen as polyelectrolytes for the LbL process, and the cross‐linking of polyelectrolytes is performed at pH 8.5. Cell division is controlled by the number of the LbL nanolayers and cross‐linking reaction. We also suggest a new measuring unit, , for quantifying “cell‐division timing” based on microbial growth kinetics.
The coordination polymerization of silyl‐protected ω‐alkenols such as ω‐alken‐α‐oxytriisopropylsilanes 1 provides poly(ω‐alkenyl‐α‐oxytriisopropylsilalne)s with a highly isospecific microstructure ([mmmm] > 95%) when a combination of [OSSO]‐type bis(phenolato) dichloro zirconium(IV) complex 2 and dried methylaluminoxane is used as the precatalyst and activator, respectively. The resulting siloxy‐substituted polymers could be efficiently transformed into the corresponding functionalized polyolefins, which contained up to 90% acetyl groups and ≈7% hydroxy groups in the terminal side chains.
Well‐defined nanogels have become quite attractive as safe and stable carriers for siRNA delivery. However, to avoid nanoparticle accumulation, they need to provide a stimuli‐responsive degradation mechanism that can be activated at the payload's site of action. In this work, the synthetic concept for generating well‐defined nanohydrogel particles is extended to incorporate disulfide cross‐linkers into a cationic nanonetwork for redox‐triggered release of oligonucleotide payload as well as nanoparticle degradation under reductive conditions of the cytoplasm. Therefore, a novel disulfide‐modified spermine cross‐linker is designed that both allows disassembly of the nanogel as well as removal of cationic charge from residual polymer fragments. The degradation process is monitored by scanning electron microscopy (SEM) and fluorescence correlation spectroscopy (FCS). Moreover, siRNA release is analyzed by agarose gel electrophoresis and a fluorescent RNA detection assay. The results exemplify the versatility of the applied nanogel manufacturing process, which allows alternative stimuli‐responsive core cross‐linkers to be integrated for triggered oligonucleotide release as well as effective biodegradation for reduced nanotoxicity.
A double‐layer hollow fiber is fabricated where an isoporous surface of polystyrene‐block‐poly(4‐vinylpyridine) is fixed on a support layer by co‐extrusion. Due to the sulfonation of the support layer material, delamination of the two layers is suppressed without increasing the number of subsequent processing steps for isoporous composite membrane formation. Electron microscope‐energy‐dispersive X‐ray spectroscopy images unveil the existence of a high sulfur concentration in the interfacial region by which in‐process H‐bond formation between the layers is evidenced. For the very first time, our study reports a facile method to fabricate a sturdy isoporous double‐layer hollow fiber.
In the last decades, metallopolymers have received great attention due to their various applications in the fields of materials and chemistry. In this article, a neutral 18‐electron exo‐substituted η4‐cyclopentadiene CpCo(I) unit‐containing polymer is prepared in a controlled/“living” fashion by combining facile click chemistry and ring‐opening metathesis polymerization (ROMP). This Co(I)‐containing polymer is further used as a heterogeneous macromolecular catalyst for atom transfer radical polymerization (ATRP) of methyl methacrylate and styrene.
