Botryoid‐shaped reactive terpolymer nanoparticles, whose aldehyde‐functional living domains are miniaturized into small‐sized discrete “grapes” and attached onto the outwardly‐branched scaffolds of fluorinated segments, are reported. These nanostructures can be fabricated by spontaneous structural reorganization of core–shell terpolymer micelles simply by manipulating drying conditions. The miniaturized discrete living domains are stabilized by outwardly‐branched scaffolds and exhibit excellent accessibility to solution media, thus can effectively respond to solution media, which is desired in sensor‐related 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.
The precise construction of a hierarchical complex pattern on substrates is required for numerous applications. Here, a strategy to fabricate well‐defined hierarchical three dimensional (3D) patterns on polymer substrate is developed. This technique, which combines photolithography and visible light‐induced surface initiated living graft crosslinking polymerization (VSLGCP), can effectively graft 3D patterns onto polymer substrate with high fidelity and controllable height. Owing to the living nature of VSLGCP, hierarchical 3D patterns can be prepared when a sequential living graft crosslinking process is performed on the first formed patterns. As a proof‐of‐concept, a reactive two layer 3D pattern with a morphology of lateral stripe on vertical stripe is prepared and employed to separately immobilize model biomolecules, e.g., biotin and IgG. This two component pattern can specifically interact with corresponding target proteins successfully, indicating that this strategy has potential applications in the fabrication of polymer‐based multicomponent biomolecule microarrays.
This paper reports the use of polyhedral oligomeric silsesquioxane (POSS)‐based copolymers to stabilize the core/shell interface for the facile fabrication of electrospun core/shell fibers. For the poly[(propylmethacryl‐heptaisobutyl‐polyhedral oligomeric silsesquioxane)‐co‐(methyl methacrylate)] (POSS‐MMA)/poly(ε‐caprolactone) (PCL) system, the bicontinuity of hybrid core/shell fibers can be tuned by controlling the phase separation of POSS‐MMA/PCL in electrospinning solutions and therefore the size of PCL‐in‐POSS‐MMA emulsion droplets. Our results demonstrate the enhanced encapsulation capacity of POSS‐MMA copolymers as shell materials. Taking advantage of the rapid advancement of POSS‐based copolymer synthesis, this study can potentially be generalized to guide the fabrication of various other POSS‐based core/shell nano‐/microstructures by using single‐nozzle electrospinning or coaxial electrospinning.
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.
Amino‐acid‐based chiral surfactants with polymerizable moieties are synthesized, and a versatile approach to prepare particles thereof with a chiral surface functionality is presented. As an example of an application, the synthesized particles are tested for their ability as nucleating agents in the enantioselective crystallization of amino acid conglomerate systems, taking rac‐asparagine as a model system. Particles resulting from chiral surfactants with different tail groups are compared and the results demonstrate that only the chiral nanoparticles made of the polymerizable surfactant are able to act efficiently as nucleation agent in enantioselective crystallization.
Temperature‐triggered phase separation of recombinant proteins has offered substantial opportunities in the design of nanoparticles for a variety of applications. Herein, the temperature‐triggered phase separation behavior of a recombinant hydrophilic resilin‐like polypeptide (RLP) is described. The transition temperature and sizes of RLP‐based nanoparticles can be modulated based on variations in polypeptide concentration, salt identity, ionic strength, pH, and denaturing agents, as indicated via UV–Vis spectroscopy and dynamic light scattering (DLS). The irreversible particle formation is coupled with secondary conformational changes from a random coil conformation to a more ordered β‐sheet structure. These RLP‐based nanoparticles could find potential use as mechanically‐responsive components in drug delivery, nanospring, nanotransducer, and biosensor applications.
This article summarizes recent progress in the post‐functionalization of conjugated polymers by electrochemical methods. These electrochemical polymer reactions typically proceed via electrochemical doping of a conjugated polymer film, followed by chemical transformation. Examples include the quantitative oxidative fluorination of polyfluorenes and oxidative halogenation of polythiophenes, as well as the reductive hydrogenation of polyfluorenones. The degree of functionalization, otherwise known as the reaction ratio, can be controlled by varying the charge passed through the polymer, allowing the optoelectronic properties of the conjugated polymers to be tailored. Wireless bipolar electrodes with an in‐plane potential distribution are also useful with regard to the electrochemical doping and reaction of conjugated polymers and allow the synthesis of films exhibiting composition gradients. Such bipolar electrochemistry can induce multiple reaction sites during electrochemical polymer reactions.
Pure quaternary tetraalkylammonium chlorides with one long alkyl chain dissolved in various organic solvents constitute a new class of cellulose solvents. The electrolytes are prepared in high yields and purity by Menshutkin quaternization, an inexpensive and easy synthesis route. The pure molten tetraalkylammonium chlorides dissolve up to 15 wt% of cellulose. Cosolvents, including N,N‐dimethylacetamide (DMA), may be added in large excess, leading to a system of decreased viscosity. Contrary to the well‐established solvent DMA/LiCl, cellulose dissolves in DMA/quaternary ammonium chlorides without any pretreatment. Thus, the use of the new solvent avoids some disadvantages of DMA/LiCl and ionic liquids, the most extensively employed solvents for homogeneous cellulose chemistry.
A photocleavable terpolymer hydrogel cross‐linked with o‐nitrobenzyl derivative cross‐linker is shown to be capable of self‐shaping without losing its physical integrity and robustness due to spontaneous asymmetric swelling of network caused by UV‐light‐induced gradient cleavage of chemical cross‐linkages. The continuum model and finite element method are used to elucidate the curling mechanism underlying. Remarkably, based on the self‐changing principle, the photosensitive hydrogels can be developed as photoprinting soft and wet platforms onto which specific 3D characters and images are faithfully duplicated in macro/microscale without contact by UV light irradiation under the cover of customized photomasks. Importantly, a quick response (QR) code is accurately printed on the photoactive hydrogel for the first time. Scanning QR code with a smartphone can quickly connect to a web page. This photoactive hydrogel is promising to be a new printing or recording material.
The sodium salt of the new bis(mesitoyl)phosphinic acid (BAPO‐OH) can be prepared in a very efficient one‐pot synthesis. It is well soluble in water and hydrolytically stable for at least several weeks. Remarkably, it acts as an initiating agent for the surfactant‐free emulsion polymerization (SFEP) of styrene to yield monodisperse, spherical nanoparticles. Time‐resolved electron paramagnetic resonance (TR‐EPR) and chemically induced electron polarisation (CIDEP) indicate preliminary mechanistic insights.
Multi‐micelle aggregation (MMA) mechanism is widely acknowledged to explicate large spherical micelles self‐assembly, but the process of MMA during self‐assembly is hard to observe. Herein, a novel kind of strong, regular microspheres fabricated from self‐assembly of amphiphilic anthracene‐functionalized β‐cyclodextrin (CD‐AN) via Cu(I)‐catalyzed azide‐alkyne click reactions is reported. The obtained CD‐AN amphiphiles can self‐assemble in water from primary core–shell micelles to secondary aggregates with the diameter changing from several tens nm to around 600–700 nm via MMA process according to the images of scanning electron microscopy, transmission electron microscopy, and atomic force microscopy as well as the dynamic light scattering measurements, followed by further crosslinking through photo‐dimerization of anthracene. What merits special attention is that such photo‐crosslinked self‐assemblies are able to disaggregate reversibly into primary nanoparticles when changing the solution conditions, which is benefited from the designed regular structure of CD‐AN and the rigid ranging of anthracene during assembly, thus confirming the process of MMA.
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 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.
A novel method, epoxidation/reduction of vegetable oils, is developed to prepare bio‐based polyols for the manufacture of polyurethanes (PUs). These polyols are synthesized from castor oil (CO), epoxidized soybean oil, and epoxidized linseed oil and their molecular structures are characterized. They are used to prepare a variety of PUs, and their thermomechanical properties are compared to those of PU made with petroleum‐based polyol (P‐450). It is shown that PUs made with polyols from soybean and linseed oil exhibit higher glass transition temperatures, tensile strength, and Young's modulus and PU made with polyol from CO exhibits higher elongation at break and toughness than PU made with P‐450. However, PU made with P‐450 displays better thermal resistance because of tri‐ester structure and terminal functional groups. The method provides a versatile way to prepare bio‐polyols from vegetable oils, and it is expected to partially or completely replace petroleum‐based polyols in PUs manufacture.
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.
A facile blending strategy to fabricate multishape memory polymers (SMPs) with only one sort of phase transition material has been reported. In this work, olefin block copolymer (OBC) and styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS), which are both physically crosslinked, are blended with crystalline paraffin together. Due to the different interactions between polymer matrices and paraffin, the paraffin penetrated in OBC and SEBS exhibit separated melting transitions. It is quite interesting that merely paraffin distributed in OBC also shows two distinct melting transitions with enough OBC content in composites. Therefore, excellent quadruple shape memory effect can be achieved with a maximum of three melting transitions. Furthermore, through adjusting the polymer species and content, the mechanical and rheological properties can be conveniently tuned to a great extent. Compared with the reported strategies, this simple and controllable method sheds light on rapid design of multi‐SMPs using inexpensive raw materials, which greatly paves the way for multi‐SMPs from laboratory to factory.
The preparation of physically crosslinked hydrogels from quasi ABA‐triblock copolymers with a water‐soluble middle block and hydrophobic end groups is reported. The hydrophilic monomer N‐acryloylmorpholine is copolymerized with hydrophobic isobornyl acrylate via a one‐pot sequential monomer addition through reversible addition fragmentation chain‐transfer (RAFT) polymerization in an automated parallel synthesizer, allowing systematic variation of polymer chain length and hydrophobic–hydrophilic ratio. Hydrophobic interactions between the outer blocks cause them to phase‐separate into larger hydrophobic domains in water, forming physical crosslinks between the polymers. The resulting hydrogels are studied using rheology and their self‐healing ability after large strain damage is shown.
In this paper, a novel synthesis of polyethylene glycol (PEG)‐modified polypyrrole (PPy) nanomaterials is demonstrated by combining reversible addition‐fragmentation chain transfer polymerization and oxidative polymerization. Dye molecules with a heat‐labile linker are used as a model drug and covalently anchored onto the PEGlated PPy nanomaterials via “click chemistry.” The strong absorption of such PPy nanomaterials in the near‐infrared region endows the system excellent photothermal effect, which can be used not only as efficient photothermal agents for photothermal therapy but also good controllers of a drug‐release system by retro D–A reaction.
Scaling behavior of one‐dimensional (1D) and two‐dimensional (2D) polymers in dilute solution is discussed with the goal of stimulating experimental work by chemists, physicists, and material scientists in the emerging field of 2D polymers. The arguments are based on renormalization‐group theory, which is explained for a general audience. Many ideas and methods successfully applied to 1D polymers are found not to work if one goes to 2D polymers. The role of the various states exhibiting universal behavior is turned upside down. It is expected that solubility will be a serious challenge for 2D polymers. Therefore, given the crucial importance of solutions in characterization and processing, synthetic concepts are proposed that allow the local bending rigidity and the molar mass to be tuned and the long‐range interactions to be engineered, all with the goal of preventing the polymer from falling into flat or compact states.
