Visible to Near-IR Electrochromism and Photothermal Effect of Poly(3,4-propylenedioxyselenophene)s

A new selenophene derivative, 3,4-propylenedioxyselenophene (ProDOS), was electropolymerized to a polymeric thin film which demonstrated wide spectral tunability from the visible to near-infrared (NIR) region. The anodic and cathodic peaks of the polymeric ProDOS (PProDOS) were observed at +0.22 and −0.30 V, showing a narrow band gap. In the visible region, the PProDOS film showed color change from navy blue in its dedoped state (−0.12 V vs Ag/AgCl) to highly transparent pale gray green in its doped state (0.68 V vs Ag/AgCl) with a high coloration efficiency (CE) of 273 cm2 C–1 and large transmittance change (contrast ratio of 5.7). The color change of the PProDOS film by electrochromism in the visible region was simultaneously accompanied by NIR electrochromism. Upon exposure to a NIR source (0.7 W cm–2), the doped PProDOS film resulted in a temperature rise of 10.7 °C compared to that of the bare indium tin oxide (ITO) coated glass, while the navy blue colored PProDOS film experienced a temperature rise of 10.2 °C. This photothermal effect by NIR light exposure was switchable between the colored and bleached state by simply dedoping and doping the film electrochemically, respectively. Furthermore, bleached PProDOS particles dispersed in water (0.05 mg mL–1) also showed a high photothermal effect (2 W cm–2) with a temperature rise of 13.1 °C, as compared to pure water. Compared with poly(3,4-ethylenedioxythiophene) (PEDOT), it was found that the new selenophene polymer (PProDOS) provided efficient visible to NIR electrochromism in addition to the high photothermal effect, resulting in a large temperature rise and heat conversion upon exposure to a NIR source

Flexible Conductive Polymer Patterns from Vapor Polymerizable and Photo-Cross-Linkable EDOT

We explored direct photopatterning of a vapor polymerizable and photo-cross-linkable 3,4-ethylenedioxythiopene (EDOT) to make it suitable for use in electronics applications. We prepared a conductive polymer, PEDOT-MA, using vapor phase polymerization (VPP) of the (2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methyl methacrylate (EDOT-MA) and photochemically induced a conductivity change of the PEDOT-MA film to ensure a flexible conductive pattern. The room-temperature conductivity (σRT) of the PEDOT-MA film on PET was 30−120 S/cm, depending on the oxidant layer thickness and was increased ∼30% when the PEDOT-MA film was doped with aqueous solution of p-toluenesulfonic acid. Photoreaction of PEDOT-MA decreased the σRT to 1.7 × 10−3 S/cm because of the photo-cross-linking of the side chain. The transparency of the conductive films was tuned using the vapor polymerization time to control the film thickness. The photo-cross-linking reaction of the side chain generated micropatterns having line widths of 50−0.9 μm, in which the light-exposed areas appeared as bleached and less conductive. A diffractive, flexible, conductive film with 41% of diffraction efficiency was obtained from the line-patterned film having a spacing of 0.9 μm

Supplementary document for Smartphone-based single snapshot spatial frequency domain imaging - 6137961.pdf

Supplemental Documen

Supplementary document for Smartphone-based single snapshot spatial frequency domain imaging - 6128053.pdf

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One-Step Synthetic Strategy of Hybrid Materials from Bimetallic Metal–Organic Frameworks for Supercapacitor Applications

This work reports a facile one-step method for the synthesis of new hybrid porous materials using bimetallic NiCo-MOF-74 as the starting precursor. By controlling the calcination atmosphere and temperature, the bimetallic NiCo-MOF-74 particles can be converted into a series of hybrid materials consisting of carbon, metal, and metal oxides. The direct carbonization of the bimetallic NiCo-MOF-74 particles at 800 °C under N₂ atmosphere results in the formation of graphitic carbon/Ni<i>_x</i>Co_1−<i>x</i> composites (termed NC-800). In contrast, the heat treatment of NiCo-MOF-74 in air at 350 °C (termed NC-350) yields Ni_<i>x</i>Co_1−<i>x</i>/Ni_<i>x</i>Co_1−<i>x</i>O composites (with a small trace of carbon) as the product. When evaluated as electrode materials for supercapacitors, NC-800 and NC-350 exhibit high specific capacitances of 715 and 513 F g^–1, respectively, at a high current density of 1 A g^–1. Furthermore, these hybrid materials also show good cycling stability with no visible degradation in their specific capacitance after 2,500 cycles. The excellent electrochemical performance of these hybrid materials may be attributed to (i) the synergistic effect of the graphitic carbon and binary mixed metals which can enhance the electrical conductivity of the composites, (ii) the presence of mesopores which can facilitate easy diffusion of electrolyte, and (iii) their large surface area and pore volume which can provide significantly more electroactive sites. The outstanding electrochemical properties of these MOF-derived hybrid materials indicate their promising potential as electrode materials for high-performance supercapacitors

Excimer Emission from Self-Assembly of Fluorescent Diblock Copolymer Prepared by Atom Transfer Radical Polymerization

Well-defined fluorescent copolymers of methyl methacrylate with 1-pyreneylmethyl methacrylate were synthesized by atom transfer radical polymerization (ATRP). The random and block copolymer could be clearly distinguished by their glass-transition temperature (Tg) values, with a single Tg value (124 °C) for the random polymer, and two Tg values (115 and 158 °C) for the block copolymer. The emission spectra of the copolymers were different in excimer emission, allowing analysis of the ordering of the two polymers, by determining the ratio between excimer emission (IE) and monomer emission (IM). The fluorescence spectra of the random copolymer exhibited both monomer and excimer emission of pyrene with a IE/IM ratio of 1.20−1.39 at a concentration of 0.001−0.05 mg/mL. The block copolymer exhibited strong excimer emission with an emission quantum yield for the excimer (ΦE) of 42%. The IE/IM ratio from the block copolymer was >25, even in a very dilute solution. The ΦE value increased to 68% when the block copolymer solution was processed to a thin film, indicating increased interactions among the pyrene block by self-assembly. In addition, nanopores were formed from the block copolymer, while no specific morphology was found from the random copolymer. The average diameter of the nanopores from block copolymer was ∼300 nm. Upon thermal annealing of the block copolymer film, a dramatic increase in excimer emission was observed to give a high ΦE value of 89%. A face-to-face pyrene assembly in the block copolymer was observed on the high-resolution transmission electron microscopy (HR-TEM) images, from which the average packing period of the well-defined pyrene block was estimated to range from 4.5 Å for pyrene block width to 5.6 Å for the width of PMMA mainchain

Hybrid Nanoarchitectonics with Conductive Polymer-Coated Regenerated Cellulose Fibers for Green Electronics

Green electronics based on biodegradable polymers have received considerable attention as a solution to electronic waste (e-waste). Herein, we describe an efficient approach to constructing green conductive fibers, comprising poly(3,4-ethylenedioxythiophene) (PEDOT) and regenerated cellulose (RC), via a wet-spinning process and vapor-phase polymerization (VPP). Eco-friendly RC fibers were prepared as a support layer by wet spinning, and the conductive PEDOT layers were coated onto the surface of the RC fibers by the oxidation of EDOT monomers. We demonstrated that the vapor-phase-polymerized PEDOT/RC composite fibers (PEDOT/RC-VPP) exhibited approximately 17 times higher electrical conductivity (198.2 ± 7.3 S/cm), compared with that of the solution-phase-polymerized PEDOT/RC composite fibers (PEDOT/RC-SPP, 11.6 ± 0.6 S/cm). Importantly, PEDOT/RC-VPP exhibited a high tensile strength of 181 MPa, good flexibility, and long-standing electrical stability under ambient air conditions. Moreover, the obtained PEDOT/RC-VPP under 50% strain turned on a green light-emitting diode (LED), indicating the flexibility and stability of green conductive fibers. This strategy can be easily integrated into various electronic textiles for the development of next-generation wearable green electronics

Controlled Chemical Vapor Deposition for Synthesis of Nanowire Arrays of Metal–Organic Frameworks and Their Thermal Conversion to Carbon/Metal Oxide Hybrid Materials

Metal–organic frameworks (MOFs) can serve as high-surface-area templates to generate hierarchically ordered nanoporous carbon electrodes for high-performance supercapacitor devices. Here we describe a simple chemical approach to synthesize dense three-dimensional (3D) arrays of core–shell ZnO@ZIF-8 and Co­(CO₃)_0.5(OH)·0.11H₂O@ZIF-67 nanowires on a conductive carbon cloth. Annealing the core–shell structures at high temperatures converted the MOF shell into a composite of nanoporous carbon (NC) mixed with conductive metal oxides. The conformal nature of the MOF-coating process generates a NC film with continuous conductive paths from the outer surfaces of the nanowires down to the flexible carbon electrode. Carbonization of ZIF-67 transforms the material into conductive <i>sp</i>² type carbon mixed with Co₃O₄ nanostructures. Because Co₃O₄ is a faradic metal oxide with a high theoretical capacitance, these Co₃O₄/NC hybrid heterostructure arrays are a promising candidate material for use in an electrochemical supercapacitor device. The Co₃O₄/NC hybrid electrodes had good performance and exhibited a high areal capacitance of 1.22 F·cm^–2 at 0.5 mA·cm^–2. Conformal deposition of MOFs via the chemical vapor method offers a promising new platform to design conductive, ultrahigh surface area electrodes that preserve the 3D morphology for applications in supercapacitors and electrocatalysis

Highly Fluorescent Conjugated Polyelectrolyte for Protein Sensing and Cell-Compatible Chemosensing Applications

Using a highly fluorescent, water-soluble polymer derived from a triazine-bridged copolymer (DTMSPV), we explored the tunable fluorescence properties of the water-soluble DTMSPV by solvent polarity to function as a fluorescence sensory probe for protein sensing. The green-blue fluorescence from DTMSPV was significantly enhanced in the presence of bovine serum albumin through hydrophobic interactions. Meanwhile, complete quenching of the fluorescence from DTMSPV occurred in the presence of hemoglobin through iron complexation with the polyelectrolyte. In addition, the DTMSPVs were highly fluorescent and permeated into living mesenchymal stem cells (MSCs), enabling effective imaging of the MSCs. This permeation into stem cells is crucial to the detection of Al³⁺ in living MSCs. The interaction between the triazine units in DTMSPV with the Al³⁺ ions allows for the detection of Al³⁺ in living cells. Thus, a strong fluorescence from living MSCs pretreated with DTMSPV was quenched as a function of the Al³⁺ concentration, confirming that DTMSPV is a cell-permeable fluorescent polymer that can function as a versatile probe to detect Al³⁺ in living cells

Hollow Microspherical and Microtubular [3 + 3] Carbazole-Based Covalent Organic Frameworks and Their Gas and Energy Storage Applications

Covalent organic frameworks (COFs) are a family of crystalline porous networks having applications in various fields, including gas and energy storage. Despite respectable progress in the synthesis of such crystalline materials, examples of the use of template-free methods to construct COFs having hollow nano- and microstructures are rare. Furthermore, all reported methods for synthesizing these hollow structural COFs have involved [4 + 2] and [3 + 2] condensations. Herein, we report the synthesis of hollow microspherical and microtubular carbazole-based COFs through template-free, one-pot, [3 + 3] condensations of the novel triamine 9-(4-aminophenyl)-carbazole-3,6-diamine (Car-3NH2) and triformyl linkers with various degrees of planarity. Depending upon the monomer’s planarity, a unique morphological variety was observed. A time-dependent study revealed that each COF formed through an individual mechanism depended on the degree of planarity of the triformyl linker; it also confirmed that the hollow structures of these COFs formed through inside-out Ostwald ripening. Our COFs exhibited high Brunauer–Emmett–Teller surface areas (up to ca. 1400 m2 g–1), excellent crystallinity, and high thermal stability. Moreover, the CO2 uptake capacities of these COFs were excellent: up to 61 and 123 mg g–1 at 298 and 273 K, respectively. The high surface areas facilitated greater numbers of strong interactions with CO2 molecules, leading to high CO2 uptake capacities. Moreover, the prepared COFs exhibited redox activity because of their redox-active triphenylamine and pyridine groups, which can be utilized in electrochemical energy storages. Accordingly, such hollow COFs having high surface areas appear to be useful materials for industrial and biological applications