Here, the preparation of a novel block copolymer consisting of a statistical copolymer N‐(2‐hydroxypropyl) methacrylamide‐s‐N‐(3‐aminopropyl) methacrylamide and a short terminal 3‐guanidinopropyl methacrylamide block is reported. This polymer structure forms neutral but water‐soluble nanosized complexes with siRNA. The siRNA block copolymer complexes are first analyzed using agarose gel electrophoresis and their size is determined with fluorescence correlation spectroscopy. The protective properties of the polymer against RNA degradation are investigated by treating the siRNA block copolymer complexes with RNase V1. Heparin competition assays confirm the efficient release of the cargo in vitro. In addition, the utilization of microscale thermophoresis is demonstrated for the determination of the binding strength between a fluorescently labeled polyanion and a polymer molecule.
Cross‐linked azobenzene liquid‐crystalline polymer films with a poly(oxyethylene) backbone are synthesized by photoinitiated cationic copolymerization. Azobenzene moieties in the film surface toward the light source are simultaneously photoaligned during photopolymerization with unpolarized 436 nm light and thus form a splayed alignment in the whole film. The prepared films show reversible photoinduced bending behavior with opposite bending directions when different surfaces of one film face to ultraviolet light irradiation.
Herein, for rate‐tunable controlled release, the authors report a new facile method to prepare multiresponsive amphiphilic supramolecular diblock copolymers via the cooperative complexation between a water‐soluble pillar[10]arene and paraquat‐containing polymers in water. This supramolecular diblock copolymer can self‐assemble into multiresponsive polymeric micelles at room temperature in water. The resultant micelles can be further used in the controlled release of small molecules with tunable release rates depending on the type of single stimulus and the combination of various stimuli.
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.
Polymeric nanosheets organized by molecular building blocks bearing specifically oriented reactive groups provide abundant and versatile strategies for tailoring structure and chemical functionality periodically over extended length scales that complement graphene. Here we report the bulk synthesis of free‐standing polymeric nanosheets via spatially confined polymerization from an elaborate 2D supramolecular system composed of two liquid‐crystalline lamellar bilayer membranes of a self‐assembled nonionic surfactant—dodecylglyceryl itaconate (DGI)—sandwiched by a water layer. By employing a covalent polymerization on the lamellar bilayer membranes, single‐bilayer‐thick (4.2 nm), and large area (greater than 100 μm2) polymeric nanosheets of bilayer membranes are achieved. The polymeric nanosheets could serve as a well‐defined 2D platform for post‐functionalization for producing advanced hybrid materials by introducing the reactions on the hydroxyl groups at the head of DGI on the outer surfaces.
An alkyne‐functionalized ruthenium(II) bis‐terpyridine complex is directly copolymerized with phenylacetylene by alkyne polymerization. The polymer is characterized by size‐exclusion chromatography (SEC), 1H NMR spectroscopy, cyclic voltammetry (CV) measurements, and thermal analysis. The photophysical properties of the polymer are studied by UV–vis absorption spectroscopy. In addition, spectro‐electrochemical measurements are carried out. Time‐resolved luminescence lifetime decay curves show an enhanced lifetime of the metal complex attached to the conjugated polymer backbone compared with the Ru(tpy)22+ model complex.
A triblock copolymer containing the complementary hydrogen bonding recognition pair ureidoguanosine–diaminonaphthyridine (UG–DAN) as pendant functional groups is synthesized using ring‐opening metathesis polymerization (ROMP). The norbornene‐based DAN monomer is shown to allow for a controlled polymerization when polymerized in the presence of a modified‐UG molecule that serves as a protecting group, subsequently allowing for the fabrication of functionalized triblock copolymers. The self‐assembly of the copolymers was characterized using dynamic light scattering and 1H NMR spectroscopy. It is demonstrated that the polymers self‐assemble via complementary hydrogen bonding motifs even at low dilutions, indicating intramolecular interactions.
Simulated‐sunlight induced atom transfer radical polymerization is used for spatial control over polymer brush growth by in situ photo‐generation of the CuI/L activator complex from its higher oxidation state CuII/L deactivator complex using dye sensitized titanium dioxide nanoparticles. The polymerization is well controlled under sunlight irradiation. Another attractive feature of this method is the possibility of creating various patterned surfaces of brushes using photomasks. When a nanoporous alumina oxide membrane is used as the template for confinement diffusion of photogenerated CuI/L catalyst, patterns with sub‐50 nm resolution are obtained.
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.
Sodium alginate (SA), acting as a trypsin inhibitor by means of electrostatic interaction, is studied. The half‐maximal inhibitory concentration (IC50 = 0.05 μg mL−1) of this natural anionic polymer is about 400 times lower than that of commercial soybean trypsin inhibitor (STI). Unlike the Ca2+‐deprivation mechanisms, its inhibition may be attributed to preventing the trypsin active site (TAS) from accessing the macromolecular substrates instead of denaturing it. SA is an efficient, innocuous, and cost‐effective inhibitory excipient that can be conveniently used in many peptide and protein dosage formulations.
Stimuli responsive surfaces that show reversible fluorescence switching behavior in response to temperature changes were fabricated. Oligo(ethylene glycol) methacrylate thermoresponsive polymers with amine end‐groups were prepared by atom transfer radical polymerization (ATRP). The polymers were patterned on silicon surfaces by electron beam (e‐beam) lithography, followed by conjugation of self‐quenching fluorophores. Fluorophore conjugated hydrogel thin films were bright when the gels were swollen; upon temperature‐induced collapse of the gels, self‐quenching of the fluorophores led to significant attenuation of fluorescence. Importantly, the fluorescence was regained when the temperature was cooled. The fluorescence switching behavior of the hydrogels for up to ten cycles was investigated and the swelling‐collapse was verified by atomic force microscopy. Morphing surfaces that change shape several times upon increase in temperature were obtained by patterning multiple stimuli responsive polymers.
In this Communication, novel water‐soluble hyperbranched polysiloxanes (WHPSs) simultaneously containing hydroxyl and primary amine groups are developed. The polymers are constructed via melt polycondensation, that is, transesterification reaction between ethoxyl groups of (3‐aminopropyl)triethoxysilane and hydroxyl groups of dihydric alcohols, using a one‐step process under catalyst‐free conditions. Surprisingly, the resultant WHPSs can emit bright blue fluorescence in the 100% solid state under the irradiation of UV light, and their photoluminescence intensities in aqueous solutions continuously go up along with increasing concentrations. Interestingly, their hydrolyzates display more intense luminescence compared to the unhydrolyzed. The efficient and easily controllable preparation strategy provides a remarkable and versatile platform for the fabrication of neoteric fluorescent materials for various potential applications.
A novel type of emulsion gel based on star‐polymer‐stabilized emulsions is highlighted, which contains discrete hydrophobic oil and hydrophilic aqueous solution domains. Well‐defined phenol‐functionalized core‐crosslinked star polymers are synthesized via reversible addition‐fragmentation chain transfer (RAFT)‐mediated dispersion polymerization and are used as stabilizers for oil‐in‐water emulsions. Horseradish‐peroxidase‐catalyzed polymerization of the phenol moieties in the presence of H2O2 enables rapid formation of crosslinked emulsion gels under mild conditions. The crosslinked emulsion gels exhibit enhanced mechanical strength, as well as widely tunable composition.
Dynamic covalent hydrogels are facilely prepared from biocompatible polysaccharides in physiological conditions by the formation of phenylboronate ester cross‐links. This is based on the simple mixing of carboxylate‐containing polysaccharides (i.e., hyaluronic acid or carboxymethylcellulose) modified with phenylboronic acid and maltose moieties according to mild coupling reactions performed in aqueous solution. The formation of dynamic networks based on reversible boronic‐ester cross‐links is demonstrated by analyzing their rheological behavior. This study shows that these gels can adapt their structure in response to chemical stimuli such as variations in pH or addition of glucose and self‐heal.
This work demonstrates a new reactive and functional hybrid (S‐MMA‐POSS) of polyhedral oligomeric silsesquioxane (POSS) and sulfur prepared with a direct reaction between a multifunctional methacrylated POSS compound (MMA‐POSS) and elemental sulfur (S8) through the “inverse vulcanization” process. S‐MMA‐POSS is an effective building block for imparting self‐healing ability to the corresponding thermally crosslinked POSS‐containing nanocomposites through a self‐curing reaction and co‐curing reaction with conventional thermosetting resins. Moreover, S‐MMA‐POSS is also a useful precursor for preparation of materials with high transparency in mid‐infrared region.
A series of fluorene‐based conjugated polymers containing the aggregation‐induced emissive (AIE)‐active tetraphenylethene and dicarboxylate pseudocrown as a receptor exhibits a unique dual‐mode sensing ability for selective detection of lead ion in water. Fluorescence turn‐off and turn‐on detections are realized in 80%–90% and 20% water in tetrahydrofuran (THF), respectively, for lead ion with a concentration as low as 10−8 m .
Porous polymer membranes made via electrostatic complexation are fabricated from a water‐soluble poly(ionic liquid) (PIL) for the first time. The porous structure is formed as a consequence of simultaneous phase separation of the PIL and ionic complexation with an acid, which occurred in a basic solution of a nonsolvent for the PIL. These membranes have a stimuli‐responsive porosity, with open and closed pores in isopropanol and in water, respectively. This property is quantitatively demonstrated in filtration experiments, where water is passing much slower through the membranes than isopropanol.
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.
Anisometric polymer colloids are likely to behave differently when compared with centrosymmetric particles. Their study may not only shine new light on the organization of matter; they may also serve as building units with specific symmetries and complexity to build new materials from them. Polymer colloids of well‐defined complex geometries can be obtained by packing a limited number of spherical polymer particles into clusters with defined configurations. Such supracolloidal architectures can be fabricated at larger scales using narrowly dispersed emulsion droplets as templates. Assemblies built from at least two different types of particles as elementary building units open perspectives in selective targeting of colloids with specific properties, aiming for mesoscale building blocks with tailor‐made morphologies and multifunctionality. Polymer colloids with defined geometries are also ideal to study shape‐dependent properties such as the diffusion of complex particles.
A self‐healing hydrogel is prepared by crosslinking acrylamide with a host–guest macro‐crosslinker assembled from poly(β‐cyclodextrin) nanogel and azobenzeneacrylamide. The photoisomerizable azobenzene moiety can change its binding affinity with β‐cyclodextrin, therefore the crosslinking density and rheology property of the hydrogel can be tuned with light stimulus. The hydrogel can repair its wound autonomously through the dynamic host–guest interaction. In addition, the wounded hydrogel will lose its ability of self‐healing when exposed to ultraviolet light, and the self‐healing behavior can be recovered upon the irradiation of visible light. The utilizing of host–guest macro‐crosslinking approach manifests the as‐prepared hydrogel reversible and light‐switchable self‐healing property, which would broaden the potential applications of self‐healing polymers.
