Two‐dimensional (2D) palladium nanocube array is achieved on plasma‐etched block copolymer templates, while the well‐aligned nanocubes remain active. Anisotropic nanocubes are site‐selectively assembled on various nanopatterns by capillary force. The nanocube array is proved to be easily tunable, and the dimensional commensurability plays a key role in the configurations of the nanocube assemblies. Not only catalytic nanocube array under confinement but also template for the growth of nanoscale zinc oxide (ZnO) nanorods is exemplified as the potential application of the nanoarray.
Here, a novel multi‐stimuli‐responsive fluorescence probe is developed by incorporating spiropyran group into the coumarin‐substituted polydiacetylene (PDA) vesicles. The fluorescence of PDA can be turned on upon heating, and can be quenched upon exposure to UV light irradiation or pH stimuli owing to the fluorescene resonance energy transfer (FRET) between the red‐phase PDA and the open merocyanine (MC) form of spiropyran. Moreover, we have designed and experimentally realized a set of logic gate operations for the first time based on the fluorescence modulation of the designed system upon thermal, photo, and pH stimuli. This novel type of resettable logic gates augur well for practical applications in information storage, optical recording, and sensing in complicated microenvironments.
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.
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 new and easy method of stimuli‐triggered growth and removal of a bioreducible nanoshell on nanoparticles is reported. The results show that pH or temperature could induce the aggregation of disulfide‐contained branched polymers at the surface of nanoparticles; subsequently, the aggregated polymers could undergo intermolecular disulfide exchange to cross‐link the aggregated polymers, forming a bioreducible polymer shell around nanoparticles. When these nanoparticles with a polymer shell are treated with glutathione (GSH) or d,l ‐dithiothreitol (DTT), the polymer shell could be easily removed from the nanoparticles. The potential application of this method is demonstrated by easily growing and removing a bioreducible shell from liposomes, and improvement of in vivo gene transfection activity of liposomes with a bioreducible PEG shell.
Herein, a novel photoinitiated polymerization‐induced self‐assembly formulation via photoinitiated reversible addition–fragmentation chain transfer dispersion polymerization of glycidyl methacrylate (PGMA) in ethanol–water at room temperature is reported. It is demonstrated that conducting polymerization‐induced self‐assembly (PISA) at low temperatures is crucial for obtaining colloidal stable PGMA‐based diblock copolymer nano‐objects. Good control is maintained during the photo‐PISA process with a high rate of polymerization. The polymerization can be switched between “ON” and “OFF” in response to visible light. A phase diagram is constructed by varying monomer concentration and degree of polymerization. The PGMA‐based diblock copolymer nano‐objects can be further cross‐linked by using a bifunctional primary amine reagent. Finally, silver nanoparticles are loaded within cross‐linked vesicles via in situ reduction, exhibiting good catalytic properties.
Hierarchical self‐assembly of transient composite hydrogels is demonstrated through a two‐step, orthogonal strategy using nanoparticle tectons interconnected through metal–ligand coordination complexes. The resulting materials are highly tunable with moduli and viscosities spanning many orders of magnitude, and show promising self‐healing properties, while maintaining complete optical transparency.
Hybrids with a silica network covalently bonded to a polymer are promising materials for bone repair. Previous work on synthesizing methyl methacrylate (MMA) based copolymers by reversible addition‐fragmentation chain transfer (RAFT) polymerization gives high tailorability of mechanical properties since sophisticated polymer structures can be designed. However, more flexible hybrids would be beneficial. Here, n‐butyl methacrylate (BMA) and methyl acrylate (MA) based hybrids are produced. Unlike MMA, BMA and MA hybrids do not show plastic deformation, and BMA hybrid has strain to failure of 33%. Although the new hybrids are more flexible, preosteoblast cells do not adhere on their surfaces, due to higher hydrophobicity and lower stiffness. Comonomer choice is crucial for bone regenerative hybrids.
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.
Enzymatic catalysis and control over macromolecular architectures from reversible addition‐fragmentation chain transfer polymerization (RAFT) are combined to give a new method of making polymers. Horseradish peroxidase (HRP) is used to catalytically generate radicals using hydrogen peroxide and acetylacetone as a mediator. RAFT is used to control the polymer structure. HRP catalyzed RAFT polymerization gives acrylate and acrylamide polymers with relatively narrow molecular weight distributions. The polymerization is rapid, typically exceeding 90% monomer conversion in 30 min. Complex macromolecular architectures including a block copolymer and a protein‐polymer conjugate are synthesized using HRP to catalytically initiate RAFT polymerization.
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 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.
Conjugated polymers may be induced by intra‐ and/or intermolecular non‐covalent forces to fold into helical conformations. Helices formed by aromatic amide, hydrazide, and urea polymers possess a well‐organized cavity and depth, which is defined by their degree of polymerization. Driving forces may be intramolecular hydrogen bonding and/or solvophobicity, or guest induction. The resulting long helices represent a new class of unimacromolecular dynamic tubular architectures that exhibit unique properties or functions in, for example, molecular recognition, chirality transfer, and ion transporting. The recent advances are highlighted here.
A novel strategy for the incorporation of carbon dioxide into polymers is introduced. For this purpose, the Ugi five‐component condensation (Ugi‐5CC) of an alcohol, CO2, an amine, an aldehyde, and an isocyanide is used to obtain step‐growth monomers. Polymerization via thiol‐ene reaction or polycondensation with diphenyl carbonate gives diversely substituted polyurethanes or alternating polyurethane‐polycarbonates, respectively. Furthermore, the application of 1,12‐diaminododecane and 1,6‐diisocyanohexane as bifunctional components in the Ugi‐5CC directly results in the corresponding polyamide bearing methyl carbamate side chains ( = 19 850 g mol−1). The latter polymer is further converted into the corresponding polyhydantoin in a highly straightforward fashion.
A triol‐functional crosslinker combining the thermoreversible properties of Diels–Alder (DA) adducts in one molecule is designed, synthesized, and used as an ideal substitute of a traditional crosslinker to prepare thermal recyclable cross‐linked polyurethanes with excellent mechanical properties and recyclability in a very simple and efficient way. The recycle property of these materials achieved by the DA/retro‐DA reaction at a suitable temperature is verified by differential scanning calorimetry and in situ variable temperature solid‐state NMR experiments during the cyclic heating and cooling processes. The thermal recyclability and remending ability of the bulk polyurethanes is demonstrated by three polymer processing methods, including hot‐press molding, injection molding, and solution casting. It is notable that all the recycled cross‐linked polymers display nearly invariable elongation/stress at break compared to the as‐synthesized samples. Further end‐group functionalization of this single molecular DA crosslinker provides the potential in preparing a wide range of recyclable cross‐linked polymers.
Two soluble poly(phenyltriazolylcarboxylate)s (PPTCs) with high molecular weights (M w up to 26 800) are synthesized by the metal‐free 1,3‐dipolar polycycloadditions of 4,4′‐isopropylidenediphenyl diphenylpropiolate ( 1 ) and tetraphenylethene‐containing diazides ( 2 ) in dimethylformamide at 150 °C for 12 h in high yields (up to 93%). The resultant polymers are soluble in common organic solvents and are thermally stable with 5% weight loss temperatures higher than 375 °C. The PPTCs are nonemissive in solutions, but become highly luminescent upon aggregation, showing a phenomenon of aggregation‐induced emission. Their aggregates can be used as fluorescent chemosensors for high‐sensitivity detection of explosives.
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.
This study demonstrates the growth of long triisopropylsilyethynyl pentacene (TIPS‐PEN) nanofibrils in a thin film of a crystalline polymer, poly(ε‐caprolactone) (PCL). During spin‐coating, TIPS‐PEN molecules are locally extracted around the PCL grain boundaries and they crystallize into [010] direction forming long nanofibrils. Molecular weight of PCL and weight fraction (α) of TIPS‐PEN in PCL matrix are key factors to the growth of nanofibrils. Long high‐quality TIPS‐PEN nanofibrils are obtained with high‐molecular‐weight PCL and at the α values in the range of 0.03–0.1. The long nanofibrils are used as an active layer in a field‐effect organic transistor.
Electrohydrodynamic cojetting has been employed to synthesize compartmentalized microfibers from thermally responsive hydrogels. The synthesis of the hydrogels as well as their transformation into compartmentalized microcylinders is discussed. After programmable shape‐shifting, snail‐like particles are obtained that undergo functional and structural reconfiguration in response to a change in temperature.
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.
