Non-ionic Surfactant F127 Research Articles

Enhancement of thermoelectric properties of La-doped SrTiO3 bulk by introducing nanoscale porosity.

Electron-doped SrTiO3 is a well-known n-type thermoelectric material, although the figure of merit of SrTiO3 is still inferior compared with p-type metal oxide-based thermoelectric materials due to its high lattice thermal conductivity. In this study, we have used a different amount of the non-ionic surfactant F127 during sample preparation to introduce nanoscale porosities into bulk samples of La-doped SrTiO3. It has been observed that the porosities introduced into the bulk sample significantly improve the Seebeck coefficient and reduce the thermal conductivity by the charge carrier and phonon scattering respectively. Therefore, there is an overall enhancement in the power factor (PF) followed by a dimensionless figure of merit (zT) over a wide scale of temperature. The sample 20 at% La-doped SrTiO3 with 600 mg of F127 surfactant (SLTO 600F127) shows the maximum PF of 1.14 mW m−1 K−2 at 647 K which is 35% higher than the sample without porosity (SLTO 0F127), and the same sample (SLTO 600F127) shows the maximum value of zT is 0.32 at 968 K with an average enhancement of 62% in zT in comparison with the sample without porosity (SLTO 0F127).

Material properties of cement paste and mortar, modified with N-doped mesoporous carbon spheres (NMCSs)

The addition of nitrogen doped mesoporous carbon spheres (NMCSs) to Portland cement-based materials was studied as an approach to produce materials of desired properties. Lower electrical resistivity and higher compressive strength were recorded in the presence of NMCSs, while the addition of a dispersion agent (Pluronic F127), caused an increase in electrical resistivity and strength reduction. This performance was related to the variation in zeta potential and hydrodynamic radius of NMCSs in alkaline medium. The zeta-potential of NMCSs was defined by the non-ionic surfactant F127. This led to a “poisoning” of the active NMCSs surface, consequently hindering the interaction of NMCSs with the cement-based material. Therefore, F127 is a non-suitable dispersing agent. In contrast, the presence of NMCSs alone enhances the desired cement-based materials properties, where reduced electrical resistivity and increased compressive strength were achieved, while cement hydration and pore network development were maintained close to NMCSs-free specimens.

Antibacterial activity of silver nanoparticles (AgNP) confined to mesostructured silica against methicillin-resistant Staphylococcus aureus (MRSA)

Prosthetic joint infection (PJI) is one of the main factors that causes joint replacement surgery failure, of which hip joint infection is the most serious. Staphylococcus aureus accounts for more than 50% of the infections caused by pathogenic microorganisms. Unfortunately, antibiotics have long been used to kill bacteria, but increasingly, multiple drug resistant pathogens (MDRP), such as methicillin-resistant Staphylococcus aureus (MRSA), have appeared and are causing a significant reduction in the efficacy of traditional antibiotics. In this study, silver nanoparticles (AgNP) confined to mesostructured silica (MS-Ag) powders were prepared to evaluate their antibacterial activity against MRSA.According to the results of thermogravimetric analysis (TGA), there was no weight loss when the temperature was greater than 600 °C. This result showed that the water, alcohol, non-ionic surfactant F127 and PUF in the silicone-containing colloid were completely removed. These results indicated that the calcination temperature for total dehydration was at least 600 °C. The as-synthesized precursor samples of MS-Ag1 were calcined directly at 400 °C, 500 °C, 550 °C and 600 °C for 2 h. The specific surface area increased over the range of 400–500 °C, and the non-ionic surfactant F127 and PUF were removed over this temperature range. Further, a transition occurred from an amorphous state to a crystalline state, and the thickness of the pore wall increased with the increasing calcination temperature over the range of 500–600 °C. Thus, the specific surface area and pore volume decreased from 526.7 m2/g and 0.84 cm3/g to 384.7 m2/g and 0.67 cm3/g, respectively.The antibacterial activity of MS-Ag powders against MRSA was verified by the disk diffusion method and time-killing curves. The minimum inhibitory concentrations (MIC) of the MS-Ag powders against MRSA were between 2.5 mg/mL and 5 mg/mL.

Hydrothermal synthesis of hierarchical flower-like Bi2WO6 microspheres with enhanced visible-light photoactivity

Three-dimensional (3D) hierarchical flower-like Bi2WO6 microspheres assembled from 2D nanosheets were successfully prepared by a simple hydrothermal route using the non-ionic surfactant F127 (EO100–PO65–EO100) as the morphology director. On the basis of the evolution of the morphologies as a function of reaction time, a possible formation mechanism for the hierarchical architecture was proposed. The photocatalytic activities of the as-prepared Bi2WO6 samples were evaluated for the degradation of Rhodamine B (RhB) under visible-light irradiation. Due to the combined effects of large surface area and efficient separation of charge carriers, the hierarchical flower-like Bi2WO6 microspheres exhibited improved photocatalytic performances.

Ordered mesoporous ternary mixed oxide materials as potential adsorbent of biomolecules

Designing a suitable mesoporous framework material for the selective adsorption or immobilization of biomolecules is a very challenging area of research. Mesoporous ternary Co–Si–Al oxide materials with large mesopore and their nanoscale ordering have been reported. The synthesis of these ternary oxides are accomplished through evaporation induced self-assembly (EISA) method using Pluronic non-ionic surfactant F127 under non-aqueous sol–gel route. N2 sorption study revealed high BET surface areas for these materials. These materials exhibited very efficient and selective adsorption for the essential biomolecules like vitamin C (ascorbic acid), vitamin B6 (pyridoxine) and vitamin B3 (nicotinic acid) from their respective aqueous solutions.

Electrospun fibrous mats as a skeleton for fabricating hierarchically structured materials as sorbents for Cu2+

Based on the combination of the electrospinning and evaporation-induced self-assembly mesopore-forming technique, a facile strategy is developed to fabricate self-standing thiol-functionalized membranes with hierarchical structures (Macro-Mesopores and binding sites). This membrane is prepared using electrospun polystyrene (PS) fibers as the skeleton and non-ionic surfactant F127 as the structure-directing agent with co-condensation of tetraethyl orthosilicate (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS). The prepared membranes were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), nitrogen sorption, mercury intrusion porosimetry, and Fourier transform infrared (FT-IR) spectra. The macropore constructed by the electrospun PS membrane ranged from 1 to 10 μm, while the highly ordered mesopore formed by F127 was around 5 nm and heavy metals binding cites of thiol groups were also presented, respectively. Using Cu2+ ions as the model bivalent cation, an excellent removal capacity of the prepared membrane was confirmed by the static sorption and dynamic filtration experiments with a high flux up to 1.30 × 104 L h−1 m−2bar−1. We find that regeneration of the membranes and the metal ion recovery can be facially realized by the treatment using acid solution. These results demonstrate that the developed strategy has significant potential for the design and fabrication of high-performance membranes with hierarchical structures and could find impactful application in the field of industrial catalysis, separation, and environmental pollution control and resources reuse.

Hierarchically structured biphenylene-bridged periodic mesoporous organosilica

Novel composites of highly ordered and stable biphenyl-bridged periodic mesoporous organosilica (PMO) materials confined within the pores of anodic alumina membranes (AAM) were successfully synthesized by evaporation-induced self-assembly (EISA). 4,4′-Bis(triethoxysilyl)biphenyl (BTEBP) was used as a precursor in combination with the ionic surfactant cetyltrimethylammonium bromide (CTAB) or triblock-copolymer F127 as structure-directing agents. The resulting mesophases were characterized by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). With ionic CTAB as a structure directing agent, samples with a mixture of the 2D-hexagonal columnar and a lamellar mesophase were obtained within the AAM channels. When using the nonionic surfactant F127, mesophases with a 2D-hexagonal circular structure were formed in the AAM channels. Additionally, a cubic Imm phase could also be obtained with the same nonionic surfactant after the addition of lithium chloride to the precursor solution. The stability of both the circular and cubic biphenylene-bridged PMO against calcination temperatures of up to 250 °C was confirmed by NMR spectroscopy. Nitrogen sorption in the porous composite membrane shows typical type IV isotherms and narrow pore size distributions. All the biphenyl PMO/AAM composites show fluorescence due to the existence of biphenyl chromophores in the stable organosilica framework.

A versatile surfactant-mediated synthetic route to gold/polyaniline derivative core/shell nanocomposites

This article describes a versatile two-step method for gold/polyaniline derivative core/shell nanocomposites with the aid of nonionic surfactant F127. First, F127 and monomer were introduced to gold colloids followed by the addition of oxidant to initiate the polymerization of monomer to afford a conducting polymer shell around each gold nanoparticle. Experimental parameters, such as kinds and concentrations of surfactant and monomer, gold core size and shape, reaction time, were systematically investigated to disclose the underground mechanisms involved in the formation of gold/polymer core/shell nanocomposites. Furthermore, Fourier transform infrared, ultraviolet–visible, X-ray diffraction, and X-ray photoelectron spectroscopy techniques were used to characterize the gold/polymer core/shell nanocomposites. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3903–3912, 2010

Luminescent Eu(iii) hybrid materials for sensor applications

In this work we use the sol-gel technique to develop different luminescent Eu(III) porous materials from a bis(trialkoxysilyl) organic precursor synthesized from the amide of the DPA (2,6-pyridinedicarboxylic acid) with APTES (aminopropyltriethoxysilane) in the presence or absence of the non-ionic surfactant F-127. The emission spectrum of the luminescent Eu(III) complex obtained was used to sense and compare the environment of the lanthanide in the amorphous matrices as well as the accessibility of the material by means of the quenching of its luminescence by Cu(II). Solid devices were built to test and compare their performances as potential sensors of Cu(II) in terms of the values of the Stern-Volmer constants in the quenching experiments. Templated materials with F127 showed the best response (K(SV) = 1.2 10(5) M(-1)) when compared with the results obtained for the non-templated ones at different synthesis conditions permitting the in situ detection of Cu(II) in solution down to the 0.05 ppm level.

Enhanced mesoporosity and capacitance property of spherical carbon aerogel prepared by associating Mg(OH) 2 with non-ionic surfactant

Non-ionic surfactant F127 (PEO 106–PPO 70–PEO 106) has been employed to enhance the mesoporosity of carbon aerogel (CA) for electric double layer capacitor application. Field emission scanning electron microscopy images exhibit that CA spheres prepared with F127 possess much coarser surface and smaller diameter. Furthermore, nitrogen sorption measurements show that the total pore volume of CA prepared with 0.6 wt.% F127 is 0.90 cm 3 g −1 and the ratio of its mesopore volume to the total pore volume (mesoporosity) could reach 86%. The specific capacitance of this CA electrode is approximately 130.8 F g −1 in 4 M KOH, which is 45% higher than that of CA solely catalyzed by Mg(OH) 2. The high specific capacitance of the CA is believed to be associated with its enhanced mesoporosity as well as the high pore volume. It also performs well in the galvanostatic charge/discharge measurement for supercapacitor.

Chemical optimisation of a sol–gel procedure for the development of fluorescence Cu(II) nanosensors

A template-assisted sol–gel procedure was developed and optimised for the preparation of silica thin films embedding the fluorescent dye 3-(dansylamido)-propyl-triethoxysilane (DNS-APTES) for Cu(II) sensing purposes. The different parameters involved (solution composition, nature of the template, deposition and annealing conditions, post-synthesis deposition of additional coatings, etc.) were independently changed in order to evaluate their effect on the final microstructure, composition and sensor performances of the films. The optimisation procedure encompassed also the choice of the suitable parameters to ensure stability of the sensing films and to avoid the leaching of the fluorescent dye. Films prepared by using the non-ionic surfactant F127, without an additional coating and with a post-deposition annealing at 100 °C for 2 h, were proven to be the best performing ones, characterised by the largest and fastest fluorescence quenching. In particular, the presence of a template was demonstrated to play a major role in determining the efficiency of the sensing device. The surface and in-depth composition of thin films was analysed by X-Ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS). The sensing performances of the films were tested by titration experiments with Cu 2+.