This study presents a new method to produce fluorescent particles. Established methods are based on the incorporation of conjugated dye molecules into dielectric polymer matrices or preparation of colloids, which are composed of fluorescent conjugated polymer. By contrast, this study presents a method where dielectric polyacrylonitrile is exposed to microwave radiation leading to an intramolecular cyclization reaction producing π‐conjugated segments, which fluoresce blue. During this conversion, the particles shrink in diameter but as an ensemble they retain their monodispersity. This work investigates the optimal reaction conditions and characterizes the optical properties.
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.
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 unique method of fabricating PS/AuNPs composite particles in ex situ mode is proposed on the basis of thermodynamically driving mechanism. It is facile and versatile as it eliminates the need for surface functionalizations and modifications of both PS microspheres and AuNPs. The PS/AuNPs composite particles take on a raspberry‐like morphology with controllable coverage according to some thermodynamic factors, which have been extensively characterized by scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. More importantly, the PS/AuNPs composite particles hold higher catalytic efficiency and better repeatability than the previously reported results, which are confirmed in two oxidation–reduction reactions of 2‐nitroaniline/NaBH4 and rhodamine B/NaBH4.
A surfactant‐free approach is proposed to synthesize nonspherical Janus particles with temperature‐dependent wettability on hydrophobic surfaces. Sub‐micrometer‐sized particles comprising poly(styrene‐co‐divinylbenzene) core and a thermally responsive poly(N‐isopropylacrylamide‐co‐methacrylic acid) shell are first synthesized to stabilize styrene droplets in water, producing a Pickering emulsion. Upon heating to 80 °C and subsequent addition of initiators to the aqueous phase, styrene droplets are polymerized and combine with the core–shell particles to construct dumbbell‐shaped nonspherical particles. The shape of the nonspherical particles is controllable by adjusting the equilibrium time of the Pickering emulsion at 80 °C, which is conducted prior to polymerization. The mechanism of formation is discussed in more detail. Since molecular surfactants or stabilizers are not used during the synthesis, the present nonspherical particles well exhibit their own temperature‐dependent amphiphilic characteristics. The aqueous dispersion containing the dumbbell‐shaped particles alters its wettability on hydrophobic polymer surfaces according to temperature changes, demonstrating its temperature‐dependent amphiphilicity change.
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.
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.
Investigation into the mussel‐inspired polymerization of dopamine has led to the realization that other compounds possessing potential quinone structures could undergo similar self‐polymerizations in mild buffered aqueous conditions. To this end, 5‐hydroxyindazole was added to a dopamine polymerization matrix in varying amounts, to study its incorporation into a polydopamine coating of silica particles. Solid‐state 13C NMR spectroscopy confirmed the presence of the indazole in the polymer shell when coated onto silica gel. SEM and DLS analysis also confirmed that the presence of the indazole in the reaction matrix yielded monodisperse polymer‐coated particles, which retained their polymer shell upon HF etching, except when high levels of the indazole were used. Characterization data and examination of incorporation mechanism suggests that the 5‐hydroxyindazole performs the function of a chain‐terminating agent. Cytotoxicity studies of the polymer particles containing 5‐hydroxyindazole showed dramatically lower toxicity levels compared to polydopamine alone.
Particles constructed by chiral polymers (defined as PCPs) have emerged as a rapidly expanding research field in recent years because of their potentially wide‐ranging applications in asymmetric catalysis, enantioselective crystallization, enantioselective release, amongst many others. The particles show considerable optical activity, due to the chirality of the corresponding polymers from which the particles are derived. This review article presents an overview on PCPs with emphasis on our group's recent achievements in the preparation of PCPs derived from optically active helical polymers and their applications. PCPs can be prepared via emulsion polymerization, precipitation polymerization, and suspension polymerization by starting from monomers. Emulsification of preformed chiral polymers and self‐assembly approaches also can lead to PCPs. Chiral polymer‐based core/shell particles, hollow particles, and magnetic particles are also covered because of their remarkable properties and significant potential applications.
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.
Functionalized polyfluorene receives more and more attention due to its wide applications. Here, the syntheses of three novel polyfluorene‐based methacrylate macromonomers exhibiting a vast flexibility for further applications are reported. Their emissions strongly depend on the end groups and thus the macromonomers provide blue, green, and red emissions simultaneously with the same excitation light of 365 nm. Their well‐defined copolymers with 2‐(dimethylamino) ethyl methacrylate via reversible addition‐fragmentation chain transfer polymerization are investigated in detail. These copolymers exhibit high quantum yields in solid film (up to 0.8), and self‐assemble into photoluminescent nanoparticles in aqueous solutions with pure blue, green, and red emissions. By simply mixing them, perfect white light emission with high quality is obtained. These aqueous nanoparticles solutions are ready for ink‐jet printing to produce exquisite bright and colorful fluorescent pictures.
Poly‐(N‐isopropylacrylamide) (PNIPA) hydrogel films doped with uniaxially aligned liquid crystalline (LC) nanosheets adsorbed with a dye are synthesized and its anomalous photothermal deformation is demonstrated. The alignment of the nanosheet LC at the cm‐scale is easily achieved by the application of an in‐plane or out‐of‐plane AC electric field during photo‐polymerization. A photoresponsive pattern is printable onto the gel with μm‐scale resolution by adsorption of the dye through a pattern‐holed silicone rubber. When the gel is irradiated with light, only the colored part is photothermally deformed. Interestingly, the photo‐irradiated gel shows temporal expansion along one direction followed by anisotropic shrinkage, which is an anomalous behavior for a conventional PNIPA gel.
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.
Janus particles with anisotropic biofunctionalities are perfect models to mimic anisotropic architectures and directional interactions that occur in nature. It is therefore highly desirable to develop reliable and efficient methods to synthesize biofunctional Janus particles. Herein, a facile method combining seeded‐emulsion polymerization and thiol‐click chemistry has been developed to synthesize Janus particles with glucose moieties on one side. These biofunctional Janus particles show region‐selective binding of protein, which represents a big step toward biomimicry, and demonstrates the potential of the bioJanus particles for targeted drug delivery and binding.
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.
Similar to the traditional self‐assembly strategy, polymerization induced self‐assembly and reorganization (PISR) can produce a myriad of polymeric morphologies through morphology transitions. Besides the chain length ratio (R) of the hydrophobic to the hydrophilic blocks, the chain mobility in the intermediate nano‐objects, which is a requisite for morphology transition, is a determining factor in the formation of the final morphology. Although various morphologies have been fabricated, hexagonally packed hollow hoops (HHHs) with highly ordered internal structure have not, to the best of our knowledge, been prepared by PISR. In this article, the fabrication of HHHs through morphology transition from large compound vesicles to HHHs is reported. HHHs with highly regular internal structure may have significance in theoretical research and practical applications of nanomaterials.
Facile and scalable fabrication methods are attractive to prepare materials for diverse applications. Herein, a method is presented to prepare cross‐linked polymeric nanoparticles with graphene oxide (GO) nanosheets covalently attached to the surface. Alkene‐modified GO serves as a surfactant in a miniemulsion polymerization, and the alkene functionalities of GO exposed to the oil‐phase are incorporated into the polymer particle through thiol‐ene reactions, leaving the unreacted alkene functional groups of the other face of GO available for further functionalization. The surface of GO‐armored polymer particles is then modified with a small molecule fluorophore or carboxylic acid functional groups that bind to Fe2O3 and TiO2 nanoparticles. This methodology provides a facile route to preparing complex hybrid composite materials.
In this article, taurine, one of the small biomolecules associated with bone metabolism, is firstly utilized to induce the fabrication of nano‐architectured conducting polypyrrole (NCPPy) on biomedical titanium in diverse pH values of phosphate buffer solution (PBS). Accordingly, the possible mechanism for the fabrication of NCPPy is proposed, which is dependent on the states of polytaurine from the polymerization of taurine, i.e., the inability of forming polytaurine and unordered restricted space results in taurine‐incorporated and polytaurine‐incorporated tightly packed nanoparticles (pH 6.2 and 8.0), respectively, and however, ordered restricted space constructed by polytaurine chains induces the fabrication of polytaurine‐incorporated nanopillars (pH 6.8) and polytaurine‐incorporated nanowire networks (pH 7.4).
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.
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.
