In this study, a new type of functional, self‐assembled nanostructure formed from porphyrins and polyamidoamine dendrimers based on hydrogen bonding in an aqueous solution is presented. As the aggregates formed are promising candidates for solar‐energy conversion, their photocatalytic activity is tested using the model reaction of methyl viologen reduction. The self‐assembled structures show significantly increased activity as compared to unassociated porphyrins. Details of interaction forces driving the supramolecular structure formation and regulating catalytic efficiency are fundamentally discussed.
For most stimuli‐responsive polymer materials (SRPMs), such as polymer gels, micelles, and brushes, the responsive mechanism is based on the solubility or compatibility with liquid media. That basis always results in distorting or collapsing the material's appearance and relies on external liquids. Here, a novel kind of SRPMs is proposed. Unlike most SRPMs, liquid is stored within special domains rather than expelled, so it is deforming‐free and relying on no external liquid, which is referred to as self‐storage SRPMs (SS‐SRPMs). The facile and universal route to fabricate SS‐SRPMs allows for another novel family of SRPMs. Furthermore, it is validated that SS‐SRPMs can drastically respond to outside temperature like switchers, especially for optical and electrochemical responses. Those features hold prospects for applications in functional devices, such as smart optical lenses or anti‐self‐discharge electrolytes for energy devices.
The hierarchical self‐assembly of an amphiphilic block copolymer, poly(N,N‐dimethylacrylamide)‐block‐polystyrene with a very short hydrophilic block (PDMA10‐b‐PS62), in large granular nanoparticles is reported. While these nanoparticles are stable in water, their disaggregation can be induced either mechanically (i.e., by applying a force via the tip of the cantilever of an atomic force microscope (AFM)) or by partial hydrolysis of the acrylamide groups. AFM force spectroscopy images show the rupture of the particle as a combination of collapse and flow, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of partly hydrolyzed nanoparticles provide a clear picture of the granular structure.
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.
Diselenide‐containing polymers are facilely synthesized from polymers prepared by atom transfer radical polymerization (ATRP). Benefiting from the ATRP technology, this protocol provides a flexible route for controlling the polymer structure, which allows for a great variety of architectures of selenium‐containing polymer materials for applications in various fields. The oxidative and reductive responsive behavior of the obtained diselenide‐containing polymers is also investigated.
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.
Molecular bottle‐brush functionalized single‐walled carbon nanotubes (SWCNTs) with superior dispersibility in water are prepared by a one‐pot synthetic methodology. Elongating the main‐chain and side‐chain length of molecular bottle‐brushes can further increase SWCNT dispersibility. They show significant enhancement of SWCNT dispersibility up to four times higher than those of linear molecular functionalized SWCNTs.
Cationic polyelectrolytes showing an upper critical solution temperature (UCST) are synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization in water at a temperature well above the UCST. The polymerization is well controlled by the RAFT process, with excellent pseudo‐first‐order kinetics. The cloud point is highly dependent on the polyelectrolyte concentration, molecular weight, and presence of added electrolyte. Alkylation of a neutral polymer is also conducted to obtain polyelectrolytes with different hydrophobic groups, which are shown to increase the cloud point.
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.
This communication reports the first example of precision polyolefin nanoalloys where an exotic immiscible polymer is nanometrically dispersed with stability in a polyolefin matrix in a highly controlled mode. Following the preparation of polypropylene/multiwalled carbon nanotubes nanocomposites (PP/MWCNTs) by in situ Ziegler‐Natta polymerization, the hydroxyl groups on the surfaces of individual MWCNTs are used to initiate ring‐opening polymerization of ε‐caprolactone, resulting in PP/poly(ε‐caprolactone) (PCL) alloy with PCL grafted on MWCNTs. Upon phase formation, the PP/MWCNTs‐g‐PCL alloys exhibit a unique PCL dispersion morphology, which is stable and solely governed by PCL molecular weight.
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.
Though great attention has been paid in constructing well‐defined nano‐structures via the self‐assembly of amphiphilic macromolecules, the self‐assembly of non‐amphiphilic macromolecules in nanodroplet has drawn less attention up to now. Recently, we prepared a temperature‐responsive PEG‐based branched polymer with disulfide bonds in its backbone via reversible addition–fragmentation chain transfer (RAFT) polymerization of 2‐(2‐methoxyethoxy) ethyl methacrylate, oligo(ethylene glycol) methacrylate, and N,N′‐cystamine bisacrylamide. Subsequently, we loaded the branched polymer into nanodroplets, and have found that the self‐assembly behaviors of this branched polymer in the nanodroplet are different from those in common solution. Bioreducible nanocapsules with tunable size can easily formed in nanodroplet even at high concentration.
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 .
Surface‐initiated photo‐induced copper‐mediated radical polymerization is employed to graft a wide range of polyacrylate brushes from silicon substrates at extremely low catalyst concentrations. This is the first time that the controlled nature of the reported process is demonstrated via block copolymer formation and re‐initiation experiments. In addition to unmatched copper catalyst concentrations in the range of few ppb, film thicknesses up to almost 1 μm are achieved within only 1 h.
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.
The chemical synthesis of a novel polyfuran, poly(2,3‐bis(hexylthio)‐[1,4]dithiino[2,3‐c]furan) ( PBDF ), substituted at the 2,3‐positions with an S‐alkylated dithiin unit, is reported. The new polymer has been characterized in terms of its electronic absorption, electrochemical, and thermal properties. Employment of the dithiin moiety provides intrinsic additional electroactivity, as well as a functional handle for substitution with alkyl groups, enhancing the processability of the polymer. The new polymer is compared with the closely related and well‐established literature compounds PEDOT and PEDTT as well‐studied, highly chalcogenated polythiophenes.
A thermally stable 2D array of spheres and their morphology control become important for the fabrication of novel nanostructures. Here, a simple method is presented for fabrication of large‐area and well‐ordered arrays of carbonized polystyrene (PS) hollow spheres with a controlled (close‐packed or non‐close‐packed hexagonal) morphology, prepared by combining the self‐assembly of PS‐grafted silica nanoparticles, etching, electron irradiation, and subsequent thermal annealing. Fine control in the 2D or 3D nanostructure of carbon materials can open up new opportunities for high‐performance nanoscale applications that require an efficient fabrication method for preparation of the porous carbon array.
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 transition‐metal catalyzed and metal‐free click polymerizations have been developed as powerful tools for the construction of functional polymers with linear and hyperbranched structures. The latter provides a thorough solution for the completely removing metallic residues from the products encountered in the former. Compared to the activated alkyne–azide metal‐free click polymerization, the activated azide–alkyne one is rarely studied. In this Communication, a perfluorophenyl‐activated azide of hexane‐1,6‐diyl‐bis(4‐azido‐2,3,5,6‐tetrafluorobenzoate) is rationally designed and facilely prepared. Through systematical optimization of the reaction conditions, an efficient metal‐free perfluorophenylazide–alkyne polycycloaddition is established, and polytriazoles with high molecular weights (up to 166 000) and excellent solubility are obtained in excellent yields (up to 93%) under mild reaction conditions. Interestingly, the regioselectivity of the reaction could be fine‐tuned by the solvents and diyne monomers. Therefore, this work provides not only a powerful tool for the preparation of functional polytriazoles, but also an attractive method for fine‐tuning their regioregularity.
In this work, activated ester chemistry is employed to synthesize biocompatible and readily functionalizable polymersomes. Via aminolysis of pentafluorophenyl methacrylate‐based precursor polymers, an N‐(2‐hydroxypropyl) methacrylamide (HPMA)‐analog hydrophilic block is obtained. The precursor polymers can be versatile functionalized by simple addition of suitable primary amines during aminolysis as demonstrated using a fluorescent dye. Vesicle formation is proven by cryoTEM and light scattering. High encapsulation efficiencies for hydrophilic cargo like siRNA are achieved using dual centrifugation and safe encapsulation is demonstrated by gel electrophoresis. In vitro studies reveal low cytotoxicity and no protein adsorption‐induced aggregation in human blood serum occurs, making the vesicles interesting candidates as nanosized drug carriers.
