Orthogonal Synthesis of Poly(aryl ether amide) Dendrons

Orthogonal Synthesis of Poly(aryl ether amide) Dendron

Enhancing Supercapacitor Performance Using Carbon Dots as Versatile Additives in Both Titanium Dioxide-Based Electrodes and Sodium Sulfate Electrolytes

In this work, carbon dots were synthesized from sodium polyacrylate and demonstrated as versatile, effective electrode/electrolyte additives for enhancing specific capacitance and cycling stability of supercapacitors. An addition of only 5 wt % carbon dots to the TiO2 electrode significantly improved the specific capacitance by 348%. Furthermore, the addition of carbon dots to the Na2SO4 electrolyte additionally enhanced the specific capacitance by 229%. This results in a total improvement of 797%, almost eightfold better than the pristine TiO2 electrode and the Na2SO4 electrolyte. The fabricated supercapacitor exhibited an areal-specific capacitance of 247 mF cm–2, the highest to date among other TiO2-based supercapacitors using Na2SO4 electrolytes. Moreover, it showed extraordinary rate capability and 96% retention of specific capacitance after 5000 cycles. From electrochemical analysis and contact angle measurement, it was shown that the carbon dots improved the performance of the supercapacitor by synergistically lowering the series resistance and enhancing the diffusion-controlled process, surface wettability, and pathways for ion diffusion. Ionic mobility and hydrated ionic radius were also found to be the critical factors in supercapacitors. The carbon dots proved to be potent additives for both TiO2-based electrodes and Na2SO4 electrolytes. The supercapacitor developed here has potential for electronic applications that require energy storage devices that exhibit environmental friendliness, excellent stability, straightforward fabrication, and low cost

Iron Oxide@PEDOT-Based Recyclable Photothermal Nanoparticles with Poly(vinylpyrrolidone) Sulfobetaines for Rapid and Effective Antibacterial Activity

Growing microbial resistance that renders antibiotic treatment vulnerable has emerged, attracting a great deal of interest in the need to develop alternative antimicrobial treatments. To contribute to this effort, we report magnetic iron oxide (Fe₃O₄) nanoparticles (NPs) coated with catechol-conjugated poly­(vinylpyrrolidone) sulfobetaines (C-PVPS). This negatively charged Fe₃O₄@C-PVPS is subsequently encapsulated by poly­(3,4-ethylenedioxythiophene) (PEDOT) following a layer-by-layer (LBL) self-assembly method. The obtained Fe₃O₄@C-PVPS:PEDOT nanoparticles appear to be novel NIR-irradiated photothermal agents that can achieve effective bacterial killing and are reusable after isolation of the used particles using external magnetic fields. The recyclable Fe₃O₄@C-PVPS:PEDOT NPs exhibit a high efficiency in converting photothermal heat for rapid antibacterial effects against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>. In this study, antibacterial tests for repeated uses maintained almost 100% antibacterial efficiency during three cycles and provided rapid and effective killing of 99% Gram-positive and -negative bacteria within 5 min of near-infrared (NIR) light exposure. The core–shell nanoparticles (Fe₃O₄@C-PVPS:PEDOT) exhibit the required stability, and their paramagnetic nature means that they rapidly convert photothermal heat sufficient for use as NIR-irradiated antibacterial photothermal sterilizing agents

Bi₂S₃ Nanorods Deposited on Reduced Graphene Oxide for Potassium-Ion Batteries

Hierarchical nanocomposites with surface active bonding features serve as an efficient electrode material for high-performance Li-/Na-/K-ion batteries. Tuning the physiochemical properties of these hierarchical nanocomposites has a great impact on the extremely improved electrochemical performance, and it is attributed to the synergistic effect of heterogeneous components. Herein, we report a hydrothermally synthesized bismuth sulfide (Bi2S3) nanorod bonding on the surface of the reduced graphene oxide (rGO) matrix and investigate it as an anode material for potassium-ion batteries. This hierarchical nanocomposite anode exhibits a high initial reversible capacity (586 mA h g–1 at 100 mA g–1), long-term cycling stability (410 mA h g–1 after 1000 cycles, 70% capacity retention), and an outstanding rate capability (140 mA h g–1 at 3 A g–1). This excellent electrochemical performance of the Bi2S3/rGO nanocomposite is attributed to the presence of active sites in rGO nanosheets that not only enhances the electrical conductivity of Bi2S3 nanorods but also prevents the shuttle effect of polysulfide through the formation of the in-built C–S bond, which is confirmed by X-ray photoelectron spectroscopy. Through the ex-situ X-ray diffraction patterns analysis at different voltage regions, a phase transformation mechanism has been proposed for K-ion storage in Bi2S3 nanorods. An ex-situ high-resolution transmission electron microscopy analysis reveals the structural and morphological stability of Bi2S3 nanorods. Further, the kinetic studies confirmed that the surface dominated pseudocapacitive K-ion storage also plays a major role in improving the electrochemical performance of the Bi2S3 nanorods/rGO nanocomposite. The K-ion full cell is successfully assembled, which exhibits stable cycling performance after 100 cycles at 1 C rate

Side-Chain-Grafted Random Copolymer Brushes as Neutral Surfaces for Controlling the Orientation of Block Copolymer Microdomains in Thin Films

Random copolymers of P(S-r-MMA-r-HEMA)s with a distribution of surface reactive hydroxyl groups were synthesized to formulate neutral surface layers on a SiO2 substrate. The layers were designed to drive vertical orientation of lamellar microdomains in a top P(S-b-MMA) thin film. Copolymers with a styrene weight fraction (fSt) of 0.58 and a HEMA fraction (fHEMA) ranging from 0.01 to 0.03, with a corresponding MMA fraction (fMMA) ranging from 0.41 to 0.39, in the P(S-r-MMA-r-HEMA) copolymer showed neutral surface characteristics. The morphology of block copolymer thin films was studied by scanning electron microscopy (SEM). P(S-r-MMA-r-HEMA) copolymers prepared by both living and classical free-radical polymerizations were equally effective in demonstrating the neutrality of the surface. These side-chain-grafted random copolymer brushes showed faster grafting kinetics than the end-chain-grafted P(S-r-MMA) because of multipoint attachment to the surface. The modified surfaces had a very thin layer of random copolymer brush (5−7 nm), which is desirable for effective pattern transfer. Furthermore, neutral surfaces could be obtained even when the grafting time was reduced to 3 h. These results indicate that the composition of the random copolymer brush, rather than its PDI or molecular weights, is the most important factor in controlling the neutrality of the surface. These results also demonstrate the feasibility of using a third comonomer (C) in the random copolymer brush P(A-r-B-r-C) to alter the interfacial and surface energies of a diblock copolymer (A-b-B)

MXene-Integrated Metal Oxide Transparent Photovoltaics and Self-Powered Photodetectors

MXene-integrated photovoltaic devices can be used to create optically transparent systems to produce electrical energy. MXenes, an emerging family of two-dimensional materials, have attracted a tremendous amount of interest for their use in various applications. In particular, their optical transparency, metallic conductivity, and large-scale processing make MXenes highly applicable in transparent photovoltaic devices (TPVDs). Here we propose a Ti3C2Tx MXene-based inorganic TPVD. Reducing the sheet resistance of MXene and improving its contact with the metal oxide (NiO/TiO2) heterojunction enables the generation of electric power (30 μW cm–2) from ultraviolet light while selectively passing visible light for high-transparency (39.73%). Moreover, the photovoltaic effect induces a high photovoltage of 0.45 V to enable the TPVD to work in self-powered mode. The MXene-embedded transparent photodetector works in photovoltaic mode and has a fast response speed of 80 μs and high detectivity of 1.6 × 1010 Jones. The spacing of the MXene-transparent devices at color-neutral coordinates in color maps indicates the invisibility of the device. This work demonstrates the large-scale application of MXene as a seamless platform for transparent electronics of photovoltaics and photodetectors. Transparent photoelectric interfaces can be used for energy generation; in bioelectronics; and in windows of building, vehicles, and displays

In Vitro and In Vivo Tumor Targeted Photothermal Cancer Therapy Using Functionalized Graphene Nanoparticles

Despite the tremendous progress that photothermal therapy (PTT) has recently achieved, it still has a long way to go to gain the effective targeted photothermal ablation of tumor cells. Driven by this need, we describe a new class of targeted photothermal therapeutic agents for cancer cells with pH responsive bioimaging using near-infrared dye (NIR) IR825, conjugated poly­(ethylene glycol)-<i>g</i>-poly­(dimethylaminoethyl methacrylate) (PEG-<i>g</i>-PDMA, PgP), and hyaluronic acid (HA) anchored reduced graphene oxide (rGO) hybrid nanoparticles. The obtained rGO nanoparticles (PgP/HA-rGO) showed pH-dependent fluorescence emission and excellent near-infrared (NIR) irradiation of cancer cells targeted in vitro to provide cytotoxicity. Using intravenously administered PTT agents, the time-dependent in vivo tumor target accumulation was exactly defined, presenting eminent photothermal conversion at 4 and 8 h post-injection, which was demonstrated from the ex vivo biodistribution of tumors. These tumor environment responsive hybrid nanoparticles generated photothermal heat, which caused dominant suppression of tumor growth. The histopathological studies obtained by H&E staining demonstrated complete healing from malignant tumor. In an area of limited successes in cancer therapy, our translation will pave the road to design stimulus environment responsive targeted PTT agents for the safe eradication of devastating cancer

Performance of NIR-Mediated Antibacterial Continuous Flow Microreactors Prepared by Mussel-Inspired Immobilization of Cs_0.33WO₃ Photothermal Agents

An antibacterial continuous flow microreactor was successfully prepared by sequential mussel-inspired surface engineering of microchannels by using catechol-grafted poly­(N-vinylpyrrolidone) and immobilization of near-infrared active Cs0.33WO3 nanoparticles inside the polydimethylsiloxane­(PDMS)-based microreactors. Excellent phothothermal antibacterial acitivity over 99.9% was accomplished toward Gram-positive and -negative bacteria upon near-infrared irradiation during continuous operation up to 30 days. This was achieved without releasing Cs0.33WO3 nanoparticles from the surface of the microchannels, confirming the robust immobilization of photothermal agents through the mussel-inspired chemistry. The cleaning of used microreactors was easily attainable by simple acid treatment to release immobilized photothermal agents from the surface of the microchannels, enabling efficient recycling of used microreactors

Light Controllable Surface Coating for Effective Photothermal Killing of Bacteria

Although the electronic properties of conducting films have been widely explored in optoelectronic fields, the optical absorption abilities of surface-coated films for photothermal conversion have been relatively less explored in the production of antibacterial coatings. Here, we present catechol-conjugated poly­(vinylpyrrolidone) sulfobetaine (PVPS) and polyaniline (PANI) tightly linked by ionic interaction (PVPS:PANI) as a novel photothermal antibacterial agent for surface coating, which can absorb broadband near-infrared (NIR) light. Taking advantage of the NIR light absorption, this coating film can release eminent photothermal heat for the rapid killing of surface bacteria. The NIR light triggers a sharp rise in photothermal heat, providing the rapid and effective killing of 99.9% of the Gram-positive and -negative bacteria tested within 3 min of NIR light exposure when used at the concentration of 1 mg/mL. Although considerable progress has been made in the design of antibacterial coatings, the user control of NIR-irradiated rapid photothermal destruction of surface bacteria holds increasing attention beyond the traditional boundaries of typical antibacterial surfaces