Search

Targeting sustainable and eco-friendly polymer synthesis, we demonstrate here a synergistically catalyzed atom transfer radical polymerization (ATRP) induced and controlled by interplay between ball milling (BM) and piezoelectric nanoparticles (piezoNPs). BM-induced electron transfer can be achieved through piezoNPs deformation under impact force, serving as an external stimulus to mediate polymerization. The ppm level of copper loading is sufficient in fabrication of a polymer with well-defined molecular weight and low polydispersity. High-molecular-weight polymers ranging from 33 to 74 kDa were prepared successfully through DMSO-assisted grinding. Besides, its good performance on availability of water as liquid-assisted grinding additive, the recyclability of piezoNPs, and the formation of cross-linker-free composite resin make our ATRP approach a green and practical option alongside the existent heat-, electro-, and photo-induced methods.

Owing to the benefits of using natural or artificial light sources as a stimulus, photoinduced reversible-deactivation radical polymerization (photoRDRP) techniques have been recognized to be a powerful "green" platform for the preparation of well-defined polymers. However, the development of highly efficient visible light-induced photoRDRP processes in aqueous dispersed media remains a challenge due to light scattering and refraction by monomer droplets or colloidal particles. In this work, an efficient green photocatalyst, carbon quantum dots (CQDs), was introduced to visible light-mediated miniemulsion atom transfer radical polymerization (ATRP), leading to highly efficient polymerizations with reaction rates (80% monomer conversion within 1 h) much higher than in previous studies. This heterogeneous photocatalytic system is presumed to involve three catalytic cycles in (i) the aqueous phase, (ii) the oil-water interface, and (iii) the monomer droplets. The effect of different polymerization parameters on the polymerization reaction was investigated, including the amounts of surfactant and CQDs, CuBr

Realizing precise control over the size and functionality of nanomaterials is a prerequisite to their diverse applications in the areas of biology, environment, energy, and other emerging nanotechnologies. Herein, we demonstrate a general template strategy capable of fabricating functional noble metallic nanorods and nanopeapods. The templates are hollow silica nanotubes (HSNTs) produced from unimolecular micelles of bottlebrush copolymers. The variation of chain length and chemical composition of bottlebrush copolymers achieved through the reversible-deactivation radical polymerization dictates the length (L), inner diameter (D), and thickness (h) of HSNTs. Using such HSNTs as nanoreactors enables the fabrication of noble metals such as Au, Ag, and Pt nanorods or nanopeapods with silica shells in a space-confined manner. While the thickness and the interior space of HSNTs regulate the diffusion and intake of metal ion precursors, the formation of nanorods or nanopeapods with different lengths and diameters is well controlled. Upon etching out the silica shell, the resulting metallic nanorods are readily functionalized with polymeric ligands for excellent dispersity in aqueous and/or organic media. This feasible and versatile strategy represents a great leap forward in the controlled synthesis of one-dimensional metallic nanomaterials and hopefully promotes understanding their structure-determined physiochemical properties and board applications in medicine and catalysis.

The past few years witnessed the rapid development of bottom-up synthesis strategies for preparing various nanostructures (i.e., nanoparticles, nanorods, nanowires, etc.) with distinct morphology-dependent properties. In this study, we reported a facile and efficient synthesis method for preparing anatase titanium dioxide (TiO2) nanorings based on multiarm, starlike amphiphilic polystyrene-b-poly(acrylic acid) (PS-b-PAA) diblock copolymers as nanoreactors which were prepared via a sequential atom-transfer radical polymerization (ATRP) technique followed by the conversion of polystyrene-b-poly(tert-butyl acrylate) (PS-b-PtBA) to PS-b-PAA. The outer PAA block of nanoreactors possessed carboxylic acid groups which could coordinate with a titanium precursor followed by high-temperature calcination to form crystalline TiO2 nanorings. The living nature of ATRP enabled the precise preparation of starlike diblock copolymer nanoreactors with a controlled length of each block (i.e., PtBA and PS), thereby tailoring the inner diameter and wall thickness of the resulting TiO2 nanorings, which were inaccessible to conventional routes.

The ambient stability and processability of organic solar cells (OSCs) are important factors for their commercialization. Herein, we selected four benzo[1,2-b:4,5-b']difuran (BDF) polymers and two electron acceptors to examine the role of photovoltaic materials in the ambient stability. The investigations revealed that the MoOx layer is the detrimental factor for the ambient stabilities. The penetration of MoOx into the active layer and their interactions will strengthen the interface and form a favorable contact, hence leading to the increased photovoltaic performance, in which the efficiency loss induced by air was balanced out. As such, these BDF polymer-based non-fullerene (NF) OSCs possessed very promising ambient stabilities even after ∼1000 h with the almost maintained power conversion efficiencies (PCEs). These results drive us to further investigate the ambient processability of these NF-OSCs. The PCEs from the devices processed under ambient condition only possessed 0.3-2% loss compared to those devices under inert conditions, which suggest the significant potentials of BDF polymers to develop highly efficient and stable NF-OSCs for the practical applications.

Near-infrared (NIR) photoinduced chemical processes are highly attractive for specific applications owing to the deep penetration of NIR into the nontransparent materials including biological and s...

The surface charge of nanocarriers inevitably affects drug delivery efficiency; however, the cancer cell specificity, anti-inflammatory effects, and charge-reversal points remain to be further addressed in biomedical applications. The aim of this study was to comprehensively assess the cancer cell specificity of DOX-loaded mesoporous silica-chitosan oligosaccharide-carboxymethyl chitosan nanoparticles (DOX@MSNs-COS-CMC) in MCF-7 and HeLa cells, inhibit the production of inflammatory cytokines, and improve the drug accumulation in the tumor site. Intracellular results reveal that the retention time prolonged to 48 h in both HeLa and MCF-7 cells at pH 7.4. However, DOX@MSNs-COS-CMC exhibited a cell type-dependent cytotoxicity and enhanced intracellular uptake in HeLa cells at pH 6.5, due to the clathrin-mediated endocytosis and macropinocytosis in HeLa cells in comparison with the vesicular transport in MCF-7 cells. Moreover, Pearson's correlation coefficient value significantly decreased to 0.25 after 8 h, prompting endosomal escape and drug delivery into the HeLa nucleus. After the treatment of MSNs-COS-CMC at 200 μg/mL, the inflammatory cytokines IL-6 and TNF-α level decreased by 70% and 80%, respectively. Tumor inhibition of DOX@MSNs-COS-CMC was 0.4 times higher than free DOX, alleviating cardiotoxicity and inflammation in the HeLa xenograft tumor model. Charge-reversible DOX@MSNs-COS-CMC could be a possible candidate for clinical therapy of cervical carcinoma.

Single pure organic molecular white light emitters (SPOMWLEs) are of significance as a new class of material for white lighting applications; however, few of them are able to emit white electroluminescence from organic light-emitting diodes. Herein, donor-π-acceptor conjugated emitters, 2PQ-PTZ and 4PQ-PTZ, were designed and synthesized as SPOMWLEs for white light emission considering the distinct advantages of their conformation isomers. The coexistence of conformational isomers in 2PQ-PTZ, which is the first experimental evidence of the coexisting quasi-axial and quasi-equatorial conformers, provides ideal flexibility to obtain white light emission from their simultaneous and well-separated fluorescence and thermally activated delayed fluorescence. With these remarkable properties, a 2PQ-PTZ-based white light-emitting diode (LED) with a CIE of (0.32, 0.34) and color rendering index (CRI) of 89 is demonstrated. Further, the white organic light-emitting diode (OLED) of 2PQ-PTZ exhibits a high external quantum efficiency (EQE) of 10.1%, which is the reported highest performance among SPOMWLE-based OLEDs.

Photocatalytic CO2 reduction to solar fuel is a promising route to alleviate the ever-growing energy crisis and global warming. Herein, to enhance photoconversion efficiency of CO2 reduction, a series of direct Z-scheme composites consisting of β-AgVO3 nanoribbons and InVO4 nanoparticles (InVO4/β-AgVO3) are prepared via a facile hydrothermal method and subsequent in situ growth process. The prepared InVO4/β-AgVO3 composites exhibit enhanced photocatalytic activity for reduction of CO2 to CO under visible-light illumination. A CO evolution rate of 12.61 μmol·g-1·h-1 is achieved over the optimized 20% In-Ag without any cocatalyst or sacrificial agent, which is 11 times larger than that yielded by pure InVO4 (1.12 μmol·g-1·h-1). Moreover, the CO selectivity is more than 93% over H2 production from the side reaction of H2O reduction. Significantly, based on the results of electron spin resonance (ESR) and in situ irradiated XPS tests, it is proposed that the synthesized InVO4/β-AgVO3 catalysts comply with the direct Z-scheme transfer mechanism. Significantly improved photocatalytic activities for selective CO2 reduction could be primarily ascribed to effective separation of photoinduced electron-hole pairs and enhanced reducibility of photoelectrons at the conduction band of InVO4. This work provides a new insight for constructing highly efficient photocatalytic CO2 reduction systems toward solar fuel generation.

Surface modification of mesoporous silica nanoparticles (MSNs) is a promising way to enhance therapeutic efficacy and minimize side effects of anticancer drugs. In this work, MSNs with reduced particle size and optimum pore diameter were obtained and catalyzed by ammonia/triethanolamine. In view of the negatively charged carboxymethyl chitosan (CMC) and positively charged chitosan oligosaccharide (CS), the pH-triggered charge-reversal CS/CMC bilayer was designed as a stimuli-responsive switch for MSNs via the protonation and deprotonation effect. The results showed that MSNs-CS/CMC were core-shell and mesoporous in structure. Surface charge conversion and pH dependence were clearly observed in the doxorubicin hydrochloride (DOX) delivery. The intracellular uptake indicated that DOX@MSNs-CS/CMC could be distributed in the cytoplasm of MCF-7 cells and exhibited lower toxicity, which would improve the stability and prolong the retention time compared to free DOX and unmodified DOX@MSNs at pH 7.4. Moreover, the cellular uptake and internalization of DOX@MSNs-CS/CMC were enhanced to promote drug delivery into the cell nucleus at pH 6.5. The biocompatible and surface-charge-reversible MSNs-CS/CMC have the potential to prolong the retention time in the bloodstream, facilitate the endosome escape, and enrich the targeted antitumor strategy, providing an alternative platform for efficient drug delivery in breast cancer therapy.

The fabrication of micro- and nanostructures in polymers has attracted considerable attention. Here, a general method defined as secondary phase separation (SPS) is developed, which regulates the g...

A facile fabrication strategy of transparent and upconversion photoluminescent nylon 6 (PA6) nanofiber mats was developed based on PA6 nanofiber mats, carboxylic acid-functionalized upconversion nanoparticles (UCNP-COOH), and poly(methyl methacrylate) (PMMA) solution. UCNP-COOH were prepared by a solvothermal method, followed by the ligand exchange process. The electrospinning method and the spin-coating process were employed to combine PA6 nanofiber mats with UCNP-COOH and PMMA to introduce upconversion photoluminescent properties and transparency into the nanocomposite mats, respectively. The prepared UCNP-COOH/PA6/PMMA nanofiber mats are transparent and exhibit green emission, which are similar to UCNP-COOH when they were excited under 980 nm laser. The upconversion luminescent intensity of the functional nanofiber mats can be tailored by adjusting the weight fraction of UCNP-COOH as fillers. This facile strategy can be readily used to other types of intriguing nanocomposites for diverse applications.

An unconventional but robust route to synthesize anatase TiO2 colloidal nanocrystals with tunable surface chemistry and dimensions was developed via liquid crystalline polyamides (LCPAs) with pyrid...

The ability to tailor the size and shape of nanoparticles (NPs) enables the investigation into the correlation between these parameters and optical, optoelectronic, electrical, magnetic, and catalytic properties. Despite several effective approaches available to synthesize NPs with a hollow interior, it remains challenging to have a general strategy for creating a wide diversity of high-quality hollow NPs with different dimensions and compositions on demand. Herein, we report on a general and robust strategy to in situ crafting of monodisperse hairy hollow noble metal NPs by capitalizing on rationally designed amphiphilic star-like triblock copolymers as nanoreactors. The intermediate blocks of star-like triblock copolymers can associate with metal precursors via strong interaction (i.e., direct coordination or electrostatic interaction), followed by reduction to yield hollow noble metal NPs. Notably, the outer blocks of star-like triblock copolymers function as ligands that intimately and permanently passivate the surface of hollow noble metal NPs (i.e., forming hairy permanently ligated hollow NPs with superior solubility in nonpolar solvents). More importantly, the diameter of the hollow interior and the thickness of the shell of NPs can be readily controlled. As such, the dimension-dependent optical properties of hollow NPs are scrutinized by combining experimental studies and theoretical modeling. The dye encapsulation/release studies indicated that hollow NPs may be utilized as attractive guest molecule nanocarriers. As the diversity of precursors are amenable to this star-like triblock copolymer nanoreactor strategy, it can conceptually be extended to produce a rich variety of hairy hollow NPs with different dimensions and functionalities for applications in catalysis, water purification, optical devices, lightweight fillers, and energy conversion and storage.

Organic-inorganic nanocomposites composed of polymers and nanoparticles offer a vast design space of potential material properties, depending heavily on the properties of these two constituents and their spatial arrangement. The ability to place polymers in direct contact with functional nanoparticles via strong bonding, that is, stable chemical interaction without the dissociation of surface capping polymers, provides a means of preventing nanoparticles from aggregation and increasing their dispersibility in nanocomposites, and promises opportunities to explore new properties and construction of miniaturized devices. However, this is still a challenging issue and has not yet been largely explored. Here, we report an unconventional strategy to create in situ organic-inorganic nanocomposites comprising monodisperse ferroelectric nanoparticles directly and permanently tethered with ferroelectric polymers by capitalizing on rationally designed amphiphilic star-like diblock copolymer as nanoreactors. The diameter of ferroelectric nanoparticles and the chain length of ferroelectric polymers can be precisely tuned. The dielectric and ferroelectric properties of nanocomposites containing different sizes of ferroelectric nanoparticles were scrutinized. Such bottom-up crafting of intimate organic-inorganic nanocomposites offers new levels of tailorability to nanostructured materials and promises new opportunities for achieving exquisite control over the surface chemistry and properties of nanocomposites with engineered functionality for diverse applications in energy conversion and storage, catalysis, electronics, nanotechnology, and biotechnology.

Atom transfer radical polymerization (ATRP) of 4-vinylpyridine, t-butyl acrylate, and styrene in sequential order from a β-cyclodextrin core yielded an amphiphilic star-like triblock copolymer, poly(4-vinylpyridine)-block-poly(t-butyl acrylate)-block-polystyrene (P4VP-b-PtBA-b-PS). Subsequently, star-like triblock copolymer composed of inner hydrophilic P4VP blocks, central hydrophobic PtBA blocks, and outer hydrophobic PS blocks with well-defined molecular architecture and molecular weight of each block was judiciously exploited as nanoreactor for synthesis of precisely shaped hairy plasmonic/semiconductor Au/TiO2 core/shell nanoparticles. The resulting Au/TiO2 nanoparticles were intimately and permanently tethered with outer PS chains that enabled the superior solubility of nanoparticles in nonpolar solvents. The PS chains on the surface of these bifunctional nanoparticles were carbonized by annealing in an inert atmosphere (i.e., yielding carbon-coated Au/TiO2 nanoparticles). In comparison to a widely ...

Unimolecular core–shell and hollow polymer nanoparticles with well-defined dimensions were crafted using spherical core–shell star-like diblock copolymers as templates. Monodisperse and structurally stable star-like diblock copolymers composed of inner degradable core blocks and outer photo-cross-linkable shell blocks were synthesized via a combination of two living polymerization techniques, namely, coordination–insertion ring opening polymerization (ROP) followed by reversible addition–fragmentation chain-transfer polymerization (RAFT). Subsequently, uniform unimolecular core–shell nanoparticles were successfully produced by photo-cross-linking the shell blocks of star-like diblock copolymers. The core diameter and shell thickness of nanoparticles are determined by molecular weights of inner core block and outer shell block, respectively, thereby rendering nanoparticles with tunable structural characteristics. The cross-linking density of nanoparticles can be readily controlled by varying the exposure t...

Cadmium telluride (CdTe) tetrapods were synthesized via multiple injections of the Te precursor by utilizing bifunctional ligands. Subsequently, tetrapod-shaped semiconducting inorganic-organic nanocomposites (i.e., P3HT-CdTe tetrapod nanocomposites) were produced by directly grafting conjugated polymer ethynyl-terminated poly(3-hexylthiophene) (i.e., P3HT-≡) onto azide-functionalized CdTe tetrapods (i.e., CdTe-N3) via a catalyst-free click chemistry. The intimate contact between P3HT and CdTe tetrapod rendered the effective dispersion of CdTe tetrapods in nanocomposites and facilitated their efficient electronic interaction. The success of coupling reaction was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The grafting density of P3HT chains on the CdTe tetrapods was estimated by thermogravimetric analysis. The photophysical properties of P3HT-CdTe tetrapod nanocomposites were studied using UV-vis and photoluminescence spectroscopies. These intimate semiconducting conjugated polymer-tetrapod nanocomposites may offer a maximized interface between conjugated polymers and tetrapods for efficient charge separation and enhanced charge transport regardless of their orientation for potential application in hybrid solar cells with improved power conversion efficiency.

A series of novel amphiphilic 21-arm, starlike diblock copolymers, poly(acrylic acid)-b-poly(3-hexylthiophene) (PAA-b-P3HT), based on β-cyclodextrin (β-CD) with well-defined molecular architectures and ratio of two chemically distinct blocks were prepared, for the first time, via a combination of quasi-living Grignard metathesis method (GRIM), click reaction, and atom transfer radical polymerization (ATRP). The starlike PAA-b-P3HT diblock copolymers consist of hydrophilic coil-like PAA cores and hydrophobic rodlike P3HT shells with narrow molecular weight distribution and well-defined molecular weight of each block. Owing to the compact structure, the amphiphilic starlike PAA-b-P3HT formed a unimolecular micelle. Emulsion based on these novel amphiphilic starlike, coil–rod diblock copolymers were readily produced by cross-linking hydrophilic coil-like PAA cores with a bifunctional cross-linker, ethylenediamine.

A series of novel amphiphilic multiarm, star-like block copolymers, poly(acrylic acid)-b-polystyrene (PAA-b-PS) based on β-cyclodextrin (β-CD) with well-defined molecular architectures, molecular weight, and ratio of two dissimilar blocks were prepared by sequential atom transfer radical polymerization (ATRP). β-CD with 21 hydroxyl groups was esterified by the reaction of its hydroxyl end groups with 2-bromoisobutyryl bromide, producing star-like heptakis[2,3,6-tri-O-(2-bromo-2-methylpropionyl]-β-cyclodextrin) (denoted 21-Br-β-CD). Subsequently, 21-Br-β-CD was utilized to initiate sequential ATRP of tert-butyl acrylate (tBA) and styrene (St). A series of 21-arm, star-like diblock copolymers, poly(tert-butyl acrylate)-b-polystyrene (PtBA-b-PS) were thus obtained. Finally, the ester groups of tBA in star-like PtBA-b-PS were selectively hydrolyzed by trifluoroacetic acid (TFA), thereby yielding amphiphilic 21-arm, star-like diblock copolymer PAA-b-PS with narrow molecular weight distribution (polydispersity ...

in which the macromonomers are copolymerized.Itiswell-knownthatcontrolledpolymerizationssuchasanionic,ATRP, and RAFT are powerful tools for the synthesis of linearpolymerswithwell-controlledmolecularweightandpolydispersity,and it is possible to make topological tailoring on polymer by thereactionsofanionwithsomefunctionalcompoundsormodificationof the end groups.