A biopolymer functionalized two-dimensional WS2@TiO2 nanocomposite for in vitro biomedical and photocatalytic applications: facile synthesis and characterization.

Organic dyes and microorganisms in industrial wastewater have harmed both the environment and human health. In this present study, the in vitro biological and photocatalytic properties of a synthesized biogenic chitosan functionalized WS2@TiO2 hybrid nanocomposite (NC) are investigated. The chitosan-functionalized WS2@TiO2 hybrid nanocomposite (NC) was synthesized hydrothermally. Its microstructure and compositional properties were studied. The antibacterial activity against Staphylococcus aureus, and Bacillus subtilis (Gram-positive) and Klebsiella pneumoniae, and Escherichia coli (Gram-negative) was evaluated. The NC exhibits the highest antibacterial activity against K. pneumoniae at bacterial inhibition zones of 27 mm. It also showed remarkable anticancer effects in MCF-7 cells (cell inhibition of 74% at 100 µg mL-1). The biocompatibility of the composite was tested against the Vero (kidney epithelial) cell line. The results suggest that the NC had no obvious cytotoxicity. Also, the NC showed good photocatalytic performance (degradation rate of 89.43% at 150 min; K = 0.0175 min-1). The results suggest that chitosan functionalized WS2@TiO2 NCs are a potential candidate for biological and environmental applications.

Fabrication of a nanoscale 2D PEDOT pattern via the combination of colloidal lithography and vapor phase polymerization for application in transparent, highly sensitive bending sensors.

Recent advances in flexible, stretchable, and wearable electronics have necessitated the development of more diverse and complex device structures; high-resolution patterning strategies for conducting polymers are therefore urgently required to enable the fabrication of these devices. In this study, we report a nanoscale patterning strategy for conductive polymer films that utilizes a combination of vapor phase polymerization (VPP) and colloidal lithography. Here, hemispherical non-close-packed colloidal crystals are used as an effective lithographic mask for patterning oxidants on a substrate; subsequently, two-dimensional honeycomb-structured porous poly(3,4-ethylenedioxythiophene) (PEDOT) films are fabricated via VPP using the prepatterned oxidant. The resulting films closely resemble the morphology of the preceding oxidant structure; furthermore, the film porosity can be altered by adjusting the polymerization time. These patterned PEDOT films exhibit high transparency owing to the presence of voids, and high electrical sensitivity to bending stresses, which were concentrated in the narrow-patterned area. As the described fabrication methods are facile and reliable, this approach therefore provides an effective route for the fabrication of various conducting polymer frameworks in the micro- to nanoscale range.

Design and Testing of Autonomous Chargeable and Wearable Sweat/Ionic Liquid-Based Supercapacitors.

This work demonstrates ionic liquid electrolyte-inscribed sweat-based dual electrolyte functioning supercapacitors capable of self-charging through sweat electrolyte function under a non-enzymatic route. The supercapacitor electrodes are fabricated from TREN (tris(2-aminoethyl)amine), poly-3,4-ethylenedioxythiophene, and a graphene oxide mixture with copper-mediated chelate, and this polymer-GO-metal chelate film can produce excellent energy harvest/storage performance from a sweat and ionic liquid integrated electrolyte system. The fabricated device is specifically designed to reduce deterioration using a typical planar structure. In the presence of sweat with ionic liquid, the dual electrolyte mode supercapacitor exhibits a maximum areal capacitance of 3600 mF cm-2 , and the energy density is 450 mWhcm-2 , which is more than 100 times greater than that from previously reported supercapacitors. The supercapacitors were fabricated/attached directly to textile fabrics as well as ITO-PET (Indium tin oxide (ITO)-polyethylene terephthalate (PET) film to study their performance on the human body during exercise. The self-charging performance with respect to sweat wetting time for the sweat@ionic liquid dual electrolyte showed that the supercapacitor performed well on both fabric and film. These devices exhibited good response for pH effect and biocompatibility, and as such present a promising multi-functional energy system as a stable power source for next-generation wearable smart electronics.

Highly porous, soft, and flexible vapor-phase polymerized polypyrrole-styrene-ethylene-butylene-styrene hybrid scaffold as ammonia and strain sensor.

Herein, in situ vapor-phase polymerization (VPP) of pyrrole on an oxidant-impregnated styrene-ethylene-butylene-styrene (SEBS) matrix comprising a three-dimensional sugar particle assembly was used to produce a soft and porous polypyrrole (PPy)-SEBS hybrid scaffold. Characterization of the PPy-SEBS hybrid scaffold using field-effect scanning electron microscopy, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and micro-computerized tomography confirmed the successful uniform and homogenous polymerization of PPy onto the SEBS matrix with a porous morphology. The performance of the hybrid scaffold of different pore sizes as an ammonia sensor under different temperature conditions was evaluated in terms of resistance change. The results showed that the PPy-SEBS scaffolds of larger pore size had higher resistance changes under lower temperature conditions when ammonia (NH3) gas was introduced compared to those observed for smaller pore sizes under higher temperature conditions. These scaffolds showed excellent repeatability and reversibility in detecting NH3 gas with fast response and recovery times of 30 s and 10-15 min, respectively. Moreover, the larger pore size scaffolds polymerized for a longer time possessed a remarkable ability to be applied as strain sensors. These kinds of novel, soft, and porous conductive polymer composite materials produced by VPP will have huge practical applications in monitoring other toxic and non-toxic gases.

Fabrication of an electroconductive, flexible, and soft poly(3,4-ethylenedioxythiophene)-thermoplastic polyurethane hybrid scaffold by in situ vapor phase polymerization.

The inherent insolubility and brittleness of poly(3,4-ethylenedioxythiophene) (PEDOT) reduce its processability and practical applicability. Herein, we use in situ vapor phase polymerization (VPP) of 3,4-ethylenedioxythiophene (EDOT) on an oxidant-impregnated thermoplastic polyurethane (TPU) matrix comprising a three-dimensional silica particle assembly to produce a soft, flexible, and conductive TPU-PEDOT hybrid scaffold. The selective removal of silica yielded a highly porous (∼95%) skeletal structure, with the effective penetration, diffusion, and polymerization of EDOT resulting in uniform PEDOT formation both on the surface and the inner side of the TPU matrix. The mechanical and electrical properties of the obtained scaffold were investigated by bending, compression testing, and stress-strain and electrical measurements. The electrical resistance of the scaffold equaled 17 kΩ and did not change after ∼500-fold bending, whereas the observed elastic modulus was much lower (300 kPa) than that of TPU (3.3 MPa). In vitro biocompatibility was investigated by MC3T3-E1 cell culturing with cell viability evaluated using the WST assay and cell morphology examined by confocal microscopy. Thus, the soft and flexible TPU-PEDOT hybrid scaffold produced by VPP might be practically useful, implying that this preliminary investigation needs to be extended to study the behavior of muscle and nerve cells under electrical stimulation.

Synthesis of Dicyclopentadiene Oligomer Over Nanoporous Al-MCM-41 Catalysts.

One step reaction composed of DCPD oligomerization and DCPD oligomer isomerization was investigated over nanoporous Al-MCM-41 catalysts. The effects of aluminum grafting over MCM-41 on the catalyst characteristics were studied with respect to the synthesis of TCPD isomer. Physical and chemical properties of the catalysts were analyzed by N2 adsorption, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The overall number of acid sites as well as the number of Lewis acid sites increased with increasing of aluminum content over MCM-41. When utilizing MCM-41 and Al-MCM-41 as the catalyst, DCPD oligomerization reaction activity greatly increased compared to the thermal reaction. The highest TCPD isomer selectivity over the Al-MCM-41 catalyst with the highest aluminum content could be ascribed to the largest amount of acid sites. This study showed an increased level of TCPD isomer selectivity by an increasing level of Lewis acid sites through aluminum addition over MCM-41.

Synthesis of Tricyclopentadiene Over Nanoporous MCM-41 Catalysts.

The objective of this study is to evaluate the catalytic potential of metal oxide/MCM-41 catalysts in dicyclopentadiene oligomerization/dicyclopentadiene oligomer isomerization. Molybdenum oxide, tungsten oxide, and titanium oxide were loaded on MCM-41 using the modified atomic layer deposition method. The amount of the acid site with weak strength has been increased through metal oxide deposition. The oligomer yield in dicyclopentadiene oligomerization/dicyclopentadiene oligomer isomerization did not change with increasing of the amount of acid site. The highest tricyclopentadiene isomer selectivity over the MoO3/MCM-41 catalyst could be attributed to having the highest overall number of acid sites among the catalysts.

A study on the electrical, optical, and physicochemical properties of poly(MMA-co-MAA)/ poly(3,4-ethylenedioxythiophene) hybrid thin films.

Poly(3,4-ethylenedioxythiophene) (PEDOT) has good properties as a conductive polymer such as high conductivity, optical transmittance, and chemical stability, while offering relatively weak physicochemical properties. The main purpose of this paper is to improve physicochemical properties such as solvent resistance and pencil hardness of PEDOT. Carboxyl groups in the poly(MMA-co-MAA) polymer chains can effectively crosslink each other in the presence of aziridine, resulting in physicochemically robust PEDOT/poly(MMA-co-MAA) hybrid conductive films. The electrical conductivity, optical properties, and physicochemical properties of the hybrid conductive film were compared by varying the solid content and poly(MMA-co-MAA) portion in the coating precursor solution. From the results, the transparency and surface resistance of the hybrid film show a tendency to decrease with increasing solid content in the coating precursor. Moreover, solvent resistance and hardness were dramatically enhanced by hybridization of PEDOT and crosslinked poly(MMA-co-MAA) due to curing reactions between carboxyl groups. The chemical composition of 30 wt-% of poly(MMA-co-MAA) (MMA:MAA mole ratio 9:1) and 3 wt-% - 5 wt-% of aziridine yields the best physicochemical properties of poly(MMA-co-MAA)/PEDOT hybrid thin films.

A selective functionalized mesoporous silica-supported Rh catalyst for effective 1-octene hydroformylation.

Through different functionalization methods, three kinds of Rh-immobilized mesoporous silicas have successfully been prepared to investigate catalytic behavior, including yield and the linear/branched ratio of aldehyde (L/B) in 1-octene hydroformylation. A conventional post grafting method and two kinds of selective bifunctionalized methods for modification of the mesoporous silica have been applied for this purpose. A relatively high L/B (> 2.0) was effectively achieved using Rh-immobilized inner pores in the MCM-41 support due to the confinement effects of the Rh complex in the nanospace. Moreover, the Rh-immobilized MCM-41 catalyst, passivated with trimethylchlorosilane (TMCS) only on the external surface, showed fairly good yields of the aldehyde (> 40%).

Removal of formaldehyde over amine functionalized SBA-15.

Amine-functionalized SBA-15 materials were synthesized by a post synthesis method. Surface area and pore size decreased by attaching functional groups to the pore surface. Furthermore, pore volume was reduced with functionalization. The carbon and nitrogen content gradually increased with the number of amine groups in the silane precursors. Among the amine-functionalized SBA-15 materials, the SBA-15/TMSPDETA showed the highest removal activity given its high reactivity with formaldehyde.

Catalytic pyrolysis of oilsand bitumen over nanoporous catalysts.

The catalytic cracking of oilsand bitumen was performed over nanoporous materials at atmospheric conditions. The yield of gas increased with application of nanoporous catalysts, with the catalytic conversion to gas highest for Meso-MFI. The cracking activity seemed to correlate with pore size rather than weak acidity or surface area.

Influence of nanopores of MCM-41 and SBA-15 confining (n-BuCp)2ZrCl2 on copolymerization of ethylene-alpha-olefin.

The effect of nanopore in mesoporous materials confining (n-BuCp),ZrCl2 and methylaluminoxane (MAO) on ethylene-1-hexene and ethylene-1-octene copolymerization was investigated on the basis of the copolymerization results, and the analysis of the supported catalyst and the copolymers. SBA-15 and MCM-41 together with amorphous silica were employed as supports, which are capable of confining (n-BuCp)2ZrCl2 and MAO in the nanopore. The copolymerization activities of MCM-41-supported (n-BuCp)2ZrCl2 were higher than those of SBA-15 and SiO2 although that its Zr content was quite lower than those of SBA-15 and SiO2. SBA-15 and MCM-41 showed a remarkable decrease in BET surface area after confining MAO and (n-BuCp)2ZrCl2 compared to SiO2, explaining an even adsorption of MAO and (n-BuCp)2ZrCl2 complexes on the nanopore surface. Temperature rising elution fractionation (TREF) results showed bimodal curves of MCM-41-supported (n-BuCp)2ZrCl2 at the C6/C2 and C8/C2 molar ratios of 0.6 and 0.5, respectively, which was attributed to the differences in ethylene and alpha-olefin concentrations along with the cylindrical nanopore of MCM-41 due to the narrow nanospace.

Synthesis of functionalized mesoporous material with various organo-silanes.

Two kinds of ordered mesoporous silicas, SBA-15 and MSU-H, have been synthesized and functionalized by direct and post synthesis method to widen their various application possibilities. In this study, phenyltrimethoxysilane (PTMS), methacryloxy-methyltrimethoxysilane (MAMTMS), 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECETMS), and N(beta-aminoethyl)-gamma-aminopropylmethyldimethoxysilane (AEAPMDMS) were used as a silane precursor for the functionalization. The post synthesis was more effective method to sustain ordered pore structure than the direct synthesis method under our experimental conditions. The surface area and pore size of mesoporous silica SBA-15 and MSU-H decreased through the functionalization process. FT-IR and XPS results confirmed the functionalized silane existence in the SBA-15/MAMTMS. These functional groups (vinyl, epoxide, and amine group) could be useful for various applications such as a linker of functional organic materials or active metal for heterogeneous catalysts. As a practical instance, rhodium immobilized on the aminated SBA-15 was investigated as a 1-octene hydroformylation.

Catalytic conversion of 1,2-dichlorobenzene over mesoporous materials from zeolite.

In this study, 1,2-dichlorobenzene (DCB), an important precursor of PCDDs and PCDFs, was chosen as a suitable model compound for the catalyzed deep oxidation of dioxin. The recently developed mesoporous materials from zeolites (MMZ) were used for the first time as a support for an oxidation catalyst. The catalytic oxidation of 1,2-dichlorobenzene over Pt/MMZ was carried out, and the catalytic activity was compared with that of Pt/gamma-Al2O3, Pt/Al-MCM-41 and Pt/Beta catalysts. Pt/MMZ showed the highest catalytic activity among the catalysts tested. Interestingly, the catalytic activity of Pt/MMZ was maintained (> 40%) at low temperatures (250 degrees C) at which the other catalysts showed extremely low activity (< 5%). The high catalytic activity of Pt/MMZ was attributed to both the sufficient acidity and mesoporosity of the MMZ support.

Influence of operation variables on fast pyrolysis of Miscanthus sinensis var. purpurascens.

Fast pyrolysis of Miscanthus was investigated in a bench-scale fluidized bed reactor for production of bio-oil. Process conditions were varied for temperature (350-550 degrees C), particle size (0.3-1.3mm), feed rate and gas flow rate. Pyrolysis temperature was the most influential parameter upon the yield and properties of bio-oil. The highest bio-oil yield of 69.2wt.% was observed at a temperature of 450 degrees C which corresponded to the end of the thermal composition of hemicellulose and cellulose. In the bio-oil, the water content was 34.5wt.%, and the main compounds in the organic fraction were phenolics and oxygenates. With increasing temperature, the amount of oxygenates in the bio-oil decreased gradually while that of water and aromatics increased rapidly. The bio-oil yield was not significantly affected by particle sizes or feed rates. The use of product gases as a fluidizing medium aided in increasing bio-oil yield.

Clean bio-oil production from fast pyrolysis of sewage sludge: effects of reaction conditions and metal oxide catalysts.

Fast pyrolysis of sewage sludge was carried out under different reaction conditions, and its effects on bio-oil characteristics were studied. The effect of metal oxide catalysts on the removal of chlorine in the bio-oil was also investigated for four types of catalysts. The optimal pyrolysis temperature for bio-oil production was found to be 450 degrees C, while much smaller and larger feed sizes adversely influenced production. Higher flow and feeding rates were more effective but did not greatly affect bio-oil yields. The use of the product gas as the fluidizing medium gave an increased bio-oil yield. Metal oxide catalysts (CaO and La2O3) contributed to a slight decrease in bio-oil yield and an increase in water content but were significantly effective in removal of chlorine from the bio-oil. The fixed catalyst bed system exhibited a higher removal rate than when metal oxide-supported alumina was used as the fluidized bed material.

Bio-oil production from fast pyrolysis of waste furniture sawdust in a fluidized bed.

The amount of waste furniture generated in Korea was over 2.4 million tons in the past 3 years, which can be used for renewable energy or fuel feedstock production. Fast pyrolysis is available for thermo-chemical conversion of the waste wood mostly into bio-oil. In this work, fast pyrolysis of waste furniture sawdust was investigated under various reaction conditions (pyrolysis temperature, particle size, feed rate and flow rate of fluidizing medium) in a fluidized-bed reactor. The optimal pyrolysis temperature for increased yields of bio-oil was 450 degrees C. Excessively smaller or larger feed size negatively affected the production of bio-oil. Higher flow and feeding rates were more effective for the production of bio-oil, but did not greatly affect the bio-oil yields within the tested ranges. The use of product gas as the fluidizing medium had a potential for increased bio-oil yields.

The preparation and low-k application of asymmetric functionalized cyclodextrin templated nanoporous silsesquioxane films.

Several kinds of Asymmetric Functionalized Cyclodextrin (AFCD), as a porogen, have been introduced for the first time to investigate their potential in the field of low-k applications. The novel AFCD templated films were compared in terms of their pore forming efficiency and the pore structure, such as pore size and pore size distribution. Of the AFCDs, btCD and tbsCD showed fairly good pore forming efficiencies. The pore diameter generating form of AFCD was larger than that of conventional CD (tCD) at a high porogen loading (> 30 wt%), which might have been due to the micelle-like assembled behavior of the AFCD porogen as a supramolecular surfactant. Ultra low-k films (k < 1.5) can be effectively made using the AFCD porogen. Mechanical properties, such as hardness and elastic modulus, decrease with increasing AFCD porogen loading.

Synthesis of nanoporous material from zeolite USY and catalytic application to bio-oil conversion.

A highly ordered nanoporous aluminosilicate (MMZ(USY)) was synthesized using commercially available zeolite USY as the framework source and cetyltrimethylammonium bromide as the template. The aluminosilicate was characterized by XRD, N2 adsorption, ICP-AES and TPD. The catalytic performance of the MMZ(USY) material in the conversion of bio-oil was compared with that of Al-MCM-41, which was synthesized using a direct sol-gel method. The highly accessible nanopores, hydrothermal stability and the intermediate acidic properties of MMZ(USY) correlated with the catalytic performance in the conversion of the bio-oil. The MMZ(USY) used in this study showed excellent activity, selectivity and stability for the production of desirable organic compounds, such as phenolics, with a high degree of deoxygenation.

Positional isomerization of butene-2 over nanoporous MCM-48 catalysts.

Positional isomerization of butene-2 to butene-1 was investigated over nanoporous MCM-48 catalysts. The effects of the method and the amount of aluminum incorporation into MCM-48 on the catalyst characteristics were studied, with respect to the butene-2 isomerization reaction. Incorporation of aluminum into MCM-48 using a post-synthetic grafting method (P) or direct sol-gel method (D) increases the total acid amount due to the increase in the Lewis acidity level. From the results of butene-2 isomerization, the yield of butene-1 was increased although the selectivity of butene-1 was decreased due to an increase of byproducts such as i-butene, cracked fraction, and C5+ hydrocarbons. This trend is nearly identical over both catalyst preparation methods; the effect of Al incorporation method on the butene-1 yield and the selectivity appeared negligible. The maximum yield of butene-1 was 27.1 wt% by feeding pure butene-2 in the reaction condition as follows: a temperature of 450 degrees C, atmospheric pressure, and with the WHSV at 70 h(-1).