A Single-Step Synthesis of Electroactive Mesoporous ProDOT-Silica Structures.

The single-step preparation of highly ordered mesoporous silica hybrid nanocomposites with conjugated polymers was explored using a novel cationic 3,4-propylenedioxythiophene (ProDOT) surfactant (PrS). The method does not require high-temperature calcination or a washing procedure. The combination of self-assembly of the silica surfactant and in situ polymerization of the ProDOT tail is responsible for creation of the mesoporosity with ultralarge pores, large pore volume, and electroactivity. As this novel material exhibits excellent textural parameters together with electrical conductivity, we believe that this could find potential applications in various fields. This novel concept of creating mesoporosity without a calcination process is a significant breakthrough in the field of mesoporous materials and the method can be further generalized as a rational preparation of various mesoporous hybrid materials having different structures and pore diameters.

Waterborne polyacrylic/PEDOT nanocomposites for conductive transparent adhesives.

A new nanocomposite for conductive transparent adhesives (CTAs) was synthesized by emulsion polymerization of acrylate monomers dispersed with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). Polymer particles of waterborne CTAs were uniform, and the average size of the particles was 330 nm. The conductive transparent adhesive nanocomposites (CTANs) were casted onto various substrates including slide glass, indium tin oxide (ITO) glass, and PET film. Upon thermal processing at 80 degrees C, highly transparent adhesive films were obtained with surface uniformity. The stress of the CTANs was affected by the contents of PEDOT:PSS, and a 7.5 wt% CTAN film had the highest maximum stress of 0.33 MPa. Importantly, polyacrylic nanoparticles were well dispersed with conductive filler PEDOT:PSS in water because of their high dispersity in water. Therefore, the polyacrylic/PEDOT nanocomposite had a low percolation threshold of approximately 8% due to the enhanced connection between conductive channels. The CTANs with an optimum content (10 wt%) of PEDOT:PSS had high electromagnetic interference shielding effectiveness (36 dB) and transparency (75%) for application to electronics including displays and solar cells.

Synthesis and preparation of fluorinated polycarbonates enhancing the light absorption of fluorescent nanoparticles.

A new synthetic method for fluorinated polycarbonates without the use of any toxic phosgene gas is presented. The synthesis consists of a monomer synthesis followed by polymerization. The fluorinated polycarbonate (FPC) was confirmed by Fourier transform infrared spectroscopy (FT-IR) and NMR spectroscopy. The refractive index of the polymer was 1.466 determined by an Abbe refractometer. The contact angle measurement of the FPC films showed the hydrophobicity with water contact angle about 112.6 degrees. These films of varying thicknesses had over 98% transmittance. Taking advantage of the hydrophobicity and high transmittance of the FPCs, nanoparticles of FPCs were prepared directly in an aqueous solution with a reprecipitation method. Combining FPC solution with a solution containing fluorescent polymer (DTMSPV), nanoparticles with a core-shell structure were obtained easily with the reprecipitation method. The fluorescence intensity of the DTMSPV in the core-shell nanoparticles were much enhanced up to 34.1% compared to the molecularly dispersed DTMSPV solution.

Nanopatterning of mesoporous inorganic oxide films for efficient light harvesting of dye-sensitized solar cells.

Nanopatterning provides facile process to well-arrayed mesoporous inorganic oxide films at low cost by using readily available pastes and elastomeric nanostamps. The fabricated nanopattern boosted the light-harvesting efficiency of dye-sensitized solar cells (DSSCs) by a light-trapping technique. The iodine-free solid-state DSSCs showed a 40 % increase in the current density and high efficiency (7.03 %).

Highly ordered poly(thiophene)s prepared in mesoporous silica nanoparticles.

Nanostructured PEDOT was synthesized using mesoporous silica as a nano-template. The polymerization of thiophene monomers was performed with an oxidant and mesoporous silica nanoparticles. The silica particles took essential role in absorbing monomers and oxidant molecules, and growth of polymers inside their pores. As prepared polymer/silica composite was treated with HF solution to remove silica template to result in 1D wire structure and mesh type porous 3D structures from SBA-15 and KIT-6 template, respectively. The average size of the poly(thiophene) wires was 10 15 nm, which was matched well to the pores size of the silica templates, as determined from an electron microscopy. At optimized condition, the room temperature electrical conductivities of the PEDOT grown from SBA-15 and KIT-6 template were similar as 1.1 and 1.0 S/cm, respectively. However, the evolution of the PEDOT conductivity versus temperature was different depending on the templates. These results gave a unique chance to tailor made 3 dimensional structure as well as properties of conductive polymer.

Preparation of conductive transparent adhesive films from carbon nanomaterials and polar acrylate.

Electrically conductive optically clear adhesives (ECOCAs) were prepared using a nanostructured carbon material (CMK-3(150)) as a conductive filler. The mesoporous carbon material, CMK-3(150), was synthesized using an ordered mesoporous silica template to produce inverse replica ordered mesoporous carbon material with an approximately 10 nm pore diameter. An adhesive solution of acrylic monomers containing polar acrylate, CMK-3(150), and thermal initiator was reacted at 80 degrees C to prepare the ECOCA composite which had appropriate viscosity for further processing. The adhesive composite was adhered to various surfaces including ITO films upon thermal processing at 60 degrees C to afford a highly transparent and adhesive film. Tensile strength of the ECOCA films was increased with the contents of conductive filler up to 4 wt%. The percolation concentration of the CMK-3(150) in the composite was approximately 7 wt%, which is much less than those of typical conductive fillers. The optimum content of CMK-3(150) to assure optical clarity, tensile strength, and high conductivity was 2-3 wt%.

Conjugated Organic Photothermal Films for Spatiotemporal Thermal Engineering.

With the growth of photoenergy harvesting and thermal engineering, photothermal materials (PTMs) have attracted substantial interest due to their unique functions such as localized heat generation, spatiotemporal thermal controllability, invisibility, and light harvesting capabilities. In particular, π-conjugated organic PTMs show advantages over inorganic or metallic PTMs in thin film applications due to their large light absorptivity, ease of synthesis and tunability of molecular structures for realizing high NIR absorption, flexibility, and solution processability. This review is intended to provide an overview of organic PTMs, including both molecular and polymeric PTMs. A description of the photothermal (PT) effect and conversion efficiency (ηPT ) for organic films is provided. After that, the chemical structure and optical properties of organic PTMs are discussed. Finally, emerging applications of organic PT films from the perspective of spatiotemporal thermal engineering principles are illustrated.

Transparent Photothermal Heaters from a Soluble NIR-Absorbing Diimmonium Salt.

While numerous near-infrared (NIR) materials have emerged, most of them are strongly colored or black due to the absorption band or tails in the visible region. Here, a highly transparent and soluble NIR-absorbing ionic salt, isobutyl-substituted diimmonium borate (IDI), is synthesized and fabricated, through a solution process, as a thin film that shows a transmittance of over 93% in the whole visible region. A transparent photothermal (PT) film heater is fabricated with the IDI-doped polymer solution, which shows a photothermal conversion efficiency (ηPT ) of 75.2%. Additionally, the prepared PT heater shows a high water evaporation conversion efficiency (ηw ) of 68.8% upon exposure to a 1064 nm laser. Furthermore, the transparent IDI film affords the development of a wireless transparent actuator for the first time, generating a bending angle over 75°, with over 2700 bending cycles. The transparent IDI film creates a hot transparent Venus flytrap and a colorful or fluorescent actuator upon the addition of colorants without losing the actuation properties.

Shape-Adaptable 2D Titanium Carbide (MXene) Heater.

Prior to the advent of the next-generation heater for wearable/on-body electronic devices, various properties are required, including conductivity, transparency, mechanical reliability, and conformability. Expansion to two-dimensional (2D) structure of metallic nanowires based on network- and mesh-type geometries has been widely exploited for realizing these heaters. However, the routes led to many drawbacks such as the low-density cross-bar linking, self-aggregation of wire, and high junction resistance. Although 2D carbon nanomaterials such as graphene and reduced graphene oxide (rGO) have shown their potentials for the purpose, CVD-grown graphene with sufficiently high conductivity was limited due to its poor processability for large-area applications, while rGO fabricated with a complex reduction process involving the use of toxic chemicals suffered from a low electrical conductivity. In this study, we demonstrate a simple and robust process, utilizing electrostatic assembling of negatively charged MXene flakes on a positively treated surface of substrate, for fabricating a metal-like 2D MXene thin film heater (TFH). Our TFH showed a high optical property (>65%), low sheet resistance (215 Ω/sq), fast electrothermal response (within dozens of seconds) with an intrinsically high electrical conductivity, and mechanical flexibility (up to 180° bending). Its capability for forming a firm and stable ionic-type interface with a counterpart surface allows us to develop a shape-adaptable and patchable thread heater (TH) that can be shaped on diverse substrates even under harsh conditions of conventional sewing or weaving processes. This work suggests that our shape-adaptable MXene heaters are potentially suitable not only for wearable devices for local heating and defrosting but also for a variety of emerging applications of soft actuators and wearable/flexible healthcare monitoring and thermotherapy.

NF-kappa B activation correlates with disease phenotype in Crohn's disease.

BACKGROUND/AIMS: Unregulated activation of nuclear factor-κB (NF-κB) plays a critical role in the pathogenesis of Crohn's disease. In this study, we investigated the clinical characteristics and disease outcome of Crohn's disease patients with varying levels of the NF-κB activation. METHODS: Crohn's disease patients who underwent surgical bowel resection were divided into two groups, based on the activation status of NF-κB. NF-κB activation was assessed by the immunoreactivity of nuclear NF-κB during immunohistochemical staining of bowel resection specimens. We compared the demographic, clinical and histologic characteristics between groups. Furthermore, the occurrence of reoperation, readmission, and medication change due to disease flare-up were investigated according to NF-κB activation status. RESULTS: Among 83 Crohn's disease patients, 47 (56%) showed high NF-κB activity and 36 (44%) showed low NF-κB activity. Patients with high NF-κB activity had higher frequency of ileocolonic involvement (P = 0.028) and lower frequency of perianal involvement (P = 0.042) relative to those with low NF-κB activity. Total histologic scores were significantly higher in patients with high NF-κB activity than those with low NF-κB activity (P = 0.044). There was no significant difference in the frequency of reoperation, readmission, and medication change in relation to NF-κB activation status. CONCLUSIONS: Crohn's disease patients with high NF-κB activation showed specific clinical manifestations of higher frequency of ileocolonic involvement and lower frequency of perianal involvement relative to those with low NF-κB activation. High NF-κB activity was associated with higher histologic scores. However, the NF-κB activity did not affect the outcome and disease course after surgery.

Dendrimer porphyrin-coated gold nanoshells for the synergistic combination of photodynamic and photothermal therapy.

A dendrimer porphyrin (DP)-coated gold nanoshell (AuNS-DP) was prepared for the synergistic combination of photodyanmic and photothermal therapy. The resultant AuNS-DP successfully exhibited the generation of reactive oxygen species (ROS) as well as photothermal effect for the simultaneous application of photodynamic therapy (PDT) and photothermal therapy (PTT).

Photothermally Activated Pyroelectric Polymer Films for Harvesting of Solar Heat with a Hybrid Energy Cell Structure.

Photothermal effects in poly(3,4-ethylenedioxythiophene)s (PEDOTs) were explored for pyroelectric conversion. A poled ferroelectric film was coated on both sides with PEDOT via solution casting polymerization of EDOT, to give highly conductive and effective photothermal thin films of PEDOT. The PEDOT films not only provided heat source upon light exposure but worked as electrodes for the output energy from the pyroelectric layer in an energy harvester hybridized with a thermoelectric layer. Compared to a bare thermoelectric system under NIR irradiation, the photothermal-pyro-thermoelectric device showed more than 6 times higher thermoelectric output with the additional pyroelectric output. The photothermally driven pyroelectric harvesting film provided a very fast electric output with a high voltage output (Vout) of 15 V. The pyroelectric effect was significant due to the transparent and high photothermal PEDOT film, which could also work as an electrode. A hybrid energy harvester was assembled to enhance photoconversion efficiency (PCE) of a solar cell with a thermoelectric device operated by the photothermally generated heat. The PCE was increased more than 20% under sunlight irradiation (AM 1.5G) utilizing the transmitted light through the photovoltaic cell as a heat source that was converted into pyroelectric and thermoelectric output simultaneously from the high photothermal PEDOT electrodes. Overall, this work provides a dynamic and static hybrid energy cell to harvest solar energy in full spectral range and thermal energy, to allow solar powered switching of an electrochromic display.

NIR-sensitive poly(3,4-ethylenedioxyselenophene) derivatives for transparent photo-thermo-electric converters.

Electrochromism, photothermal effect, and thermoelectric properties of hexyl-derivatized poly(3,4-ethylenedioxyselenophene) are investigated by precisely controlling the morphology. These properties are clearly demonstrated by controlling the applied electrical potential of the polymer films. Especially, the doped polymer film at -0.1 V reveals the highest photothermal conversion efficiency and a power factor of 42.5% and 354.7 µW m(-1) K(-2) , respectively. Efficient visible to near-infrared absorption, photon to heat, and heat to electric conversion has been realized in one film that could benefit in exploiting multifunctional film displays, invisible NIR sensors, photodynamic theragnosis, and thermoelectric devices.

Noninvasive photodetachment of stem cells on tunable conductive polymer nano thin films: selective harvesting and preserved differentiation capacity.

Viable mesenchymal stem cells (MSCs) were efficiently and selectively harvested by near-infrared (NIR) light using the photothermal effect of a conductive polymer nano thin film. The poly(3,4-ethylenedioxy thiophene) (PEDOT)-coated cell culture surfaces were prepared via a simple and fast solution-casting polymerization (SCP) technique. The absorption of PEDOT thin films in the NIR region was effectively triggered cell harvesting upon exposure to an NIR source. By controlling the NIR absorption of the PEDOT film through electrochemical doping or growing PEDOT with different thin film thickness from 70 to 300 nm, the proliferation and harvesting of MSCs on the PEDOT surface were controlled quantitatively. This light-induced cell detachment method based on PEDOT films provides the temporal and spatial control of cell harvesting, as well as cell patterning. The harvested stem cells were found to be alive and well proliferated despite the use of temperature increase by NIR. More importantly, the harvested MSCs by this method preserved their intrinsic characteristics as well as multilineage differentiation capacities. This PEDOT surfaces could be used for repetitive culture and detachment of MSCs or for efficient selection or depletion of a specific subset from heterogeneous population during culture of various tissue-derived cells because there were no photodegradation and photobreakage in the PEDOT films by NIR exposure.

Electroactive subwavelength gratings (ESWGs) from conjugated polymers for color and intensity modulation.

Subwavelength gratings with electroactive polymers such as poly(3-hexylthiophene) (P3HT) and poly(3,4-propylenedioxythiophene-phenylene) (P(ProDOT-Ph)) controlled the color intensity for various visible colors of diffracted light in a single device. Under the illumination of a white light, at a fixed angle of incidence, the color intensity of the diffracted light was reversibly switched from the maximum value down to 15% (85% decrease) by applying -2 to 2 V due to electrochemical (EC) reaction. All spectral colors including red, green, and blue were generated by changing the angle of incidence, and the intensity of each color was modulated electrochemically at a single EC device. With electroactive subwavelength gratings (ESWGs) of P3HT, the maximum modulation of the color intensity was observed in the red-yellow quadrant in the CIE color plot, whereas for the ESWGs of P(ProDOT-Ph), the maximum modulation of the color intensity was observed in the yellow-green and green-blue quadrants. Both ESWGs showed a memory effect, keeping their color and intensity even after power was turned off for longer than 40 hours.

Room temperature solid-state synthesis of a conductive polymer for applications in stable I2-free dye-sensitized solar cells.

A solid-state polymerizable monomer, 2,5-dibromo-3,4-propylenedioxythiophene (DBProDOT), was synthesized at 25 °C to produce a conducting polymer, poly(3,4-propylenedioxythiophene) (PProDOT). Crystallographic studies revealed a short interplane distance between DBProDOT molecules, which was responsible for polymerization at low temperature with a lower activation energy and higher exothermic reaction than 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) or its derivatives. Upon solid-state polymerization (SSP) of DBProDOT at 25 °C, PProDOT was obtained in a self-doped state with tribromide ions and an electrical conductivity of 0.05 S cm⁻¹, which is considerably higher than that of chemically-polymerized PProDOT (2×10⁻6 S cm⁻¹). Solid-state ¹³C NMR spectroscopy and DFT calculations revealed polarons in PProDOT and a strong perturbation of carbon nuclei in thiophenes as a result of paramagnetic broadening. DBProDOT molecules deeply penetrated and polymerized to fill nanocrystalline TiO2 pores with PProDOT, which functioned as a hole-transporting material (HTM) for I2-free solid-state dye-sensitized solar cells (ssDSSCs). With the introduction of an organized mesoporous TiO2 (OM-TiO2) layer, the energy conversion efficiency reached 3.5 % at 100 mW cm⁻², which was quite stable up to at least 1500 h. The cell performance and stability was attributed to the high stability of PProDOT, with the high conductivity and improved interfacial contact of the electrode/HTM resulting in reduced interfacial resistance and enhanced electron lifetime.