Block Copolymer Pluronic P123 Research Articles

Electrosynthesis and Performance of Homogeneously Mesoporous Ni-Rich Ni-Pt Thin Films for Efficient Hydrogen Evolution Reaction in Acidic Media

The development of green hydrogen technology requires abundant electrocatalyst materials to (partially) replace costly platinum while maintaining the catalytic efficiency and durability. Nickel is an excellent choice for the partial replacement of Pt for water splitting, and is widely used for electrocatalysis in alkaline media. Although Ni cannot provide an activity identical to Pt, specific nanostructures aimed at a high surface-to-volume ratio, such as nanoporous structures, can significantly improve catalytic efficiency. However, in acidic media, the use of non-noble metals for electrocatalysis requires extensive durability tests to confirm the stability of the alloy. Additionally, the impact of hydrogen itself is often overlooked, as hydrogen is known to cause hydrogen embrittlement in Ni and its alloys.This contribution deals with the synthesis of a homogeneously mesoporous Ni-Pt alloy with high catalytic efficiency (Fig. 1). By electrodeposition from aqueous media, Ni-rich Ni-Pt alloy thin films are synthesised in a wide compositional range (between 60 and 99 at% Ni), depending on the deposition potential. The addition of the amphiphilic block copolymer Pluronic P-123 to the electrolyte formulation enables a micelle-assisted deposition process, resulting in films with homogeneous porosity with an approximate pore size of 10 nm irrespective of composition. Moreover, all thin films are single-phase and nanocrystalline [1], and show excellent performance under hydrogen evolution reaction (HER) in acidic media [2].As determined by Rutherford backscattering (RBS), the as-deposited Ni-Pt thin films with film thickness between 180 nm and 260 nm exhibit Pt enrichment at the surface of 1-2 nm in depth, after which Ni and Pt exhibit constant composition over depth. After hydrogen evolution in 0.5 M H2SO4, a gradient in Ni/Pt ratio over the film thickness is established, indicating preferential leaching of Ni into the electrolyte, and resulting in higher Pt content at the surface. Due to the porosity of the thin films, this leaching affects the entire film thickness. A chronopotentiometric durability test (24 h) reveals that the overpotential stabilises over time, indicating that the leaching of Ni is suppressed once a certain Pt/Ni ratio is attained in the thin films. In addition, the HER electrocatalysis is accompanied by a significant hydrogen uptake, determined by elastic recoil detection analysis (ERDA). Depending on the electrodeposition parameters, the as-deposited thin films already exhibit significant hydrogen concentrations between 2 and 10 at%. After the HER durability test, local cracking is observed by SEM, related to an excess of hydrogen in the thin films. Despite the cracking, no significant detachment of the films from the substrate is observed. The hydrogen contained in the films is assumed to be interstitial and does not affect the metallic nature of the Ni-Pt films. An X-ray photoelectron spectroscopy (XPS) post-analysis shows that the fraction of metallic Ni with respect to Ni in higher oxidation states is higher after exposure to the HER than for the as-prepared surface. Acknowledgement: Financed by the European Union – NextGenerationEU.[1] K. Eiler, J. Fornell, C. Navarro-Senent, E. Pellicer, J. Sort, Nanoscale, 2020, 12, 7749[2] K. Eiler, S. Suriñach, J. Sort, E. Pellicer, Appl. Catal. B, 2020, 265, 118597Figure 1: SEM micrograph of a mesoporous Ni93Pt7 thin film. Figure 1

Determination of drug loading efficiency of nano capsules formed by the O/W emulsification of block copolymer

The self-assembly nature of pluronic triblock copolymers have been exploited by materials scientists in the field of drug delivery. We have used Pluronic P123 block copolymer to load an antibiotic drug Amoxicillin and have analyzed the drug loading efficiency. The amphiphilic nature and micellization of Pluronic P123block copolymer was efficiently utilized and the morphology of drug loaded block copolymer is analyzed in detail and correlated with the loading efficiency. Moreover this study also focuses on the antimicrobial activities of the amoxicillin loaded Pluronic P123block copolymer. It is seen that the micelle serve as excellent payloads for the delivery of the most common drug amoxicillin.

Adsorption of lead(II), cadmium(II) and dysprosium(III) from aqueous solutions using mesoporous silica modified with phosphonic acid groups

The mesoporous silica samples with different concentrations of phosphonic acid groups on the surface were obtained by direct template synthesis. The block-copolymer Pluronic P123 was used as a template, and sodium meta-silicate with diethylphosphatoethyltriethoxysilane as precursors. According to the SAXS diffractograms, mesoporous silica samples have a p6mm hexagonal symmetry. In addition, we used sol–gel method to synthesize xerogel with the same groups for comparison. All samples possess high values of specific surface area 615–730 m2/g and sorption pore volume. FTIR and potentiometric titration methods were used to investigate the surface layer of these samples. Sorption properties of the samples with phosphonic acid groups were studied in respect to a row of metal cations, among which we focused on lead(II), cadmium(II), and dysprosium(III) cations.

Synthesis, Magneto-structural Properties and Colloidal Stability Studies of Ni0.3Zn0.7Fe2O4 Nanoparticles Coated with Pluronic P123 Block Copolymer for Potential Biomedical Applications

Spinel Ni0.3Zn0.7Fe2O4 (NZFO) magnetic nanoparticles was prepared by the low temperature auto-combustion method using a glycine fuel-rich composition without any further heat treatment at high temperature. Subsequently, the synthesized MNPs were coated with Pluronic P123 (PP123) after its surface was functionalized with oleic acid (OA). The effect of the coatings on the morphology, structural and magnetic properties of NZFO nanoparticles was studied using powder X-ray diffraction (XRD), Fourier transform infrared, thermogravimetric analysis, field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM). The colloidal behaviour of coated MNPs in physiological saline medium like water or phosphate buffer saline (PBS) was also studied by zeta potential measurements. XRD results showed the formation of cubic spinel crystalline phase with and without OA–PP123 coatings. Also, after OA–PP123 coating, the crystallite size (from Scherrer formula) decreases from 55 to 53 nm. However, an enlargement in the particle size and a reduction in agglomeration were observed from FE-SEM results when the nanoparticles were coated with OA–PP123. VSM measurements showed ferromagnetic behaviour at room temperature before and after coating. The colloidal stability study of the coated sample revealed a considerable high zeta potential value at physiological pH (7.4) highlighting its potential biomedical applications.

Influence of synthesis conditions on morphological features of the SBA-15 containing only elongated and rounded/spherical grains

Mesoporous silica SBA-15 materials of high specific surface area (~700 m2 g?1) were synthesized by using block copolymer Pluronic P123 as template and tetraethoxysilane as silica source. The obtained materials were characterized by XRD, nitrogen adsorption - desorption measurements, SEM, EDS and AFM analysis. It was found that small modifications of synthesis conditions influenced the morphological features of the synthesized SBA-15 samples. The SEM analysis had shown that the SBA-15 synthesized at lower temperature and longer time of reaction (80?C, 48 h) provided elongated rod-shaped grains about 1?m long. The other sample synthesized at higher temperature and shorter time of reaction (100 ?C, 24 h) had rounded grains and grains of regular spherical shape with diameters ranging from 0.5 to 2 ?m. The EDS analysis confirmed that the particles of both synthesized samples were of the SiO2 content. In addition, the AFM analysis had shown different surface morphologies of the materials synthesized under various conditions.

Synthesis and structure of pyridine-functionalized mesoporous SBA-15 organosilicas and their application for sorption of diclofenac

A series of pyridine-functionalized mesoporous silicas have been prepared for the first time via direct co-condensation of tetraethoxysilane (TEOS) and 2-(2-pyridyl)ethyltrimethoxysilane (PETS) using the block copolymer Pluronic P123 as a structure-directing agent. The obtained materials were fully characterized by a wide range of instrumental techniques and employed as adsorbents for the removal of a diclofenac which is considered a priority hazardous drug. The synthesized materials exhibit a high adsorption capacities and rapid adsorption rates. The structural and adsorption properties depend largely on the relative amount of PETS/TEOS ratio: the gradual degradation of ordered structure and porosity was observed with the increasing amount of PETS. However due to the highest loading of pyridine units the most structurally degraded material had the highest adsorption uptake (631mgg−1) indicating that the surface chemistry plays – along with porosity – an important role in governing the adsorption process. The experimental adsorption data were modelled using the Langmuir, Freundlich and Langmuir-Freundlich isotherms – among them the Langmuir-Freundlich model turned out to be the most suitable for describing adsorption behaviour of diclofenac onto the materials. The collected data show that the pyridine-functionalized mesoporous silicas can be a promising absorbent of pharmaceuticals.

Synthesis of mesoporous tungsten oxide by template-assisted sol–gel method and its photocatalytic degradation activity

In this study, mesoporous tungsten oxide nanostructure was successfully synthesized using inexpensive peroxotungstic acid as a tungsten precursor, and pluronic P123 blockcopolymer as a template. Various techniques such as differential thermal analysis, thermogravimetric analysis, Fourier transformed infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, nitrogen adsorption/desorption analysis, and UV–Vis spectroscopy were utilized to characterize the prepared tungsten oxide. Nitrogen adsorption/desorption analysis demonstrated the formation of mesoporous structure with the specific surface area of 67 m2/g and pore size of ~ 6 nm after calcination at 500 oC for 1 h. Microstuctural investigation by field emission scanning electron microscopy images revealed the existence of spherical morphology for the prepared mesoporous tungsten oxide powder. X-ray diffraction analysis confirmed the formation of orthorhombic crystalline structure. In addition, the calculated energy band gap of the calcined product was found to be 2.60 eV. Further, photocatalytic activity of the synthesized crystalline powder was verified for Rhodamine B degradation, giving rise to 79% dye removal from aqueous solution with 6 mg/L concentration under ultraviolet irradiation.

Synthesis of pore-expanded mesoporous ZIF-8/silica composites in the presence of swelling agent

The synthesis of mesoporous zeolitic imidazolate framework-8/silica composites with foam-like structure templated by Pluronic P123 (EO 20 PO 70 EO 20 ) block copolymer surfactant in the presence of swelling agent was demonstrated in this study. It was found that 1,3,5-trimethylbenzene was a suitable swelling agent, which worked effectively in the pluronic-P123-templated synthesis of zeolitic imidazolate framework-8/silica composites when a moderate amount was added. The pore diameter of the foams in resulting composites increased to 50–60 nm when the 1,3,5-trimethylbenzene /P123 weight ratio of 3/4 was used during the synthesis. In addition, the composite with enlarged diameter of foams showed superior adsorption capacity to phthalic acid (H2-PA) at 20 °C in comparison with aggregated bulk zeolitic imidazolate framework-8.

Sodium silicate as source of silica for synthesis of mesoporous SBA-15

Ordered mesoporous silica SBA-15 was prepared using hydrothermal synthesis using sodium silicate (Na2SiO3) as the silica source and amphiphilic block copolymer Pluronic P123 as the structure directing agent. The influence of the mass Na2SiO3, ripening duration, aging time and calcination temperature on the structural and mesoporous properties of silica was studied. X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscopy (SEM) and the nitrogen adsorption desorption using Brunauer Emmett Teller (BET) are some instruments used to characterize the results of investigation. From XRD analysis, SBA-15 synthesized from sodium silicate yield 2D-hexagonal symmetry (p6mm). From FTIR analysis, functional group Si-O-Si symmetric stretching modes and asymmetric Si- O-Si stretching modes were present. The sample with the highest mass of Na2SiO3 and the shortest aging time exhibited the largest surface area and large pore size. The results also showed the morphological structure could be tuned during ripening stage.

Pd–Cu alloy with hierarchical network structure as enhanced electrocatalysts for formic acid oxidation

Pd–Cu alloy with hierarchical porous network structure is prepared via a facile one-pot hydrothermal reaction, by using a mixed solvent of ethylene glycol and water as the reaction media, and the block copolymer Pluronic P123 as the structure-directing agent. The Pd–Cu alloy networks are constructed by hierarchically assembled nanorods as building blocks. The structure, porosity, surface chemical state and electrochemical properties of as-prepared Pd–Cu alloy are characterized and analyzed. Owing to the superior hierarchical porous network structure, the Pt–Cu alloy catalysts present remarkably enhanced catalytic performance toward formic acid oxidation, in comparison with the commercial Pd black.

High performance perovskite solar cells with functional highly porous TiO2 thin films constructed in ambient air

In the present work we report the synthesis of highly meso- and macro-porous thin TiO2 films as efficient scaffolds for improved performance of heterojunction solid state perovskite solar cells made in Fambient air. TiO2 films were prepared using sol–gel process and Pluronic P-123 block copolymer as organic template while they were formed on conductive glass substrates by spin-coating method. The films were employed to the construction of very efficient perovskite solar cells made at ambient conditions where CH3NH3PbI3−xClx mixed halide perovskite was used as light harvester and P3HT polymer as hole conductor. The very rough and highly porous TiO2 films proved to be an excellent host material for perovskite growth. The structural properties of the TiO2 electron transport layer, thickness, particle size and porosity, strongly affected the overall conversion efficiency. The optimal structure and materials composition exhibited a notably high current density Jsc of 23.8mA/cm2, Voc of 0.995V and fill factor of 0.58. These solar cells prepared under ambient conditions yielded an average power conversion efficiency of 13.7% among the best ever recorded with P3HT polymer as hole conducting material.

Influence of ZnO addition on the structural, in vitro behavior and antimicrobial activity of sol–gel derived CaO–P2O5–SiO2 bioactive glasses

Bone formation, mineralization and bacterial growth control are challenging issues when developing biomedical materials. Mesoporous bioactive glasses (MBGs) in 70SiO2–(26−x) CaO–4P2O5–xZnO (x=0, 3 and 5mol %) were synthesized by a sol–gel method using the non-ionic block copolymer Pluronic P123 as structure directing agent. The IV type nitrogen adsorption/desorption isotherms and pore size values between 3 and 6nm confirmed the mesoporous structure of the synthesized MBGs. For the biological evaluation, the effect of CaO/ZnO substitution on the in vitro bioactivity of the prepared MBGs was studied by immersion in simulated body fluid (SBF) at 37°C for 14 and 28 days, respectively. The consequent formation of the hydroxyl apatite (HA) layer and structural discrepancies of the formed layer were studied by means of appropriate techniques such as: X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), FT-IR and Raman Spectroscopy. The rate of HA precipitation followed the order 0Zn>3Zn>5Zn. The concentration of Ca, Si, P and Zn ions released from the samples into the SBF was monitored by X-ray fluorescence (XRF). High inhibition rates of 91.3% for Bacillus subtilis and respectively 89.4% for Pseudomonas aeruginosa after 2h of incubation indicate a very good antibacterial activity of the glass with 5% ZnO.

Synthesis and catalytic cracking performance of mesoporous zeolite Y

Mesoporous zeolite Y (denoted as meso-Y) was synthesized using hydrothermal synthesis method using pluronic P123 block copolymer as template. Furthermore, stabilized Y (USY) was prepared through ion exchange and ultra-stabilization process of the meso-Y. The catalysts were prepared and characterized by XRD, SEM, TEM, N2 adsorption–desorption, NH3-TPD and Py-IR. These catalysts were evaluated by determining the micro-activity using the light diesel oil as sample. The results showed that the Meso-CAT-3 catalyst had the highest micro-activity and lowest coke yield. It could be ascribed to the mesoporous structure which is known to improve the mass transfer of the larger molecules.

Facile one-step synthesis of micro/mesoporous material with ordered bimodal mesopores templated by protic ionic liquid as a heterogeneous catalyst support for alkylation

Nanosized hierarchical micro/mesoporous composites were successfully fabricated using non-ionic block copolymer Pluronic P123 and protic ionic liquid (butylamine acetate) as the co-templates. The obtained samples were characterized by several techniques, including small angle X-ray scattering, N2 gas sorption, scanning electron microscope and transmission electron microscopy. The result established that the final silica materials possessed a disordered population of micropores coexisting with two different mesoporous channels of 4.0 and 7.3 nm. The formation mechanism of the micro/mesoporous silica which is based on the interaction between PIL and P123 is tentatively elucidated. 12-Tungstophosphoric acid catalysts incorporated into these micro/mesoporous materials were prepared by impregnation, and their catalytic performances were investigated in the alkylation of o-xylene with styrene. Alkylation results exhibited that all the catalysts showed the high catalytic performance in terms of propane conversion and selectivity to propene.

Pluronic-P123-Templated Synthesis of Silica with Cubic Ia3d Structure in the Presence of Micelle Swelling Agent.

The syntheses of silicas with highly ordered cubic Ia3d structure templated by Pluronic P123 (EO20PO70EO20) block copolymer surfactant and sodium dodecyl sulfate (SDS) additive in the presence of swelling agents are demonstrated. It was found that the cubic Ia3d silica forms at 25 °C when a moderate amount of a swelling agent, such as 1,3,5-triisopropylbenzene (TIPB), 1,4-diisopropylbenzene (DIPB), or 1,3,5-triethylbenzene (TEB), is added. However, 1,3,5-trimethylbenzene was not found suitable, suggesting that the success of the synthesis requires a careful selection of a swelling agent. An increase in the relative amount of the swelling agent in a limited range tends to cause an increase in the unit-cell size, while a further unit cell parameter increase can be accomplished with TIPB through a concomitant decrease in the synthesis temperature and increase in the relative amount of the swelling agent. Many of the cubic Ia3d products, including those with the largest attained unit-cell sizes, were highly ordered. When TIPB was used as a swelling agent, the products typically had unusually high mesopore volumes. The latter was largely independent of the ratio of the silica precursor to the Pluronic P123 surfactant for high quality products obtained under particular conditions, which suggests that the cubic Ia3d structure forms at a nearly constant silica-to-surfactant ratio.

CO₂ adsorption on amine-functionalized periodic mesoporous benzenesilicas.

CO2 adsorption was investigated on amine-functionalized mesoporous silica (SBA-15) and periodic mesoporous organosilica (PMO) samples. Hexagonally (p6mm) ordered mesoporous SBA-15 and benzene-PMO (BPMO) samples were prepared in the presence of Pluronic P123 block copolymer template under acidic conditions. Three kinds of amine-containing organosilanes and polyethylenimine were used to functionalize SBA-15 and BPMO. Small-angle X-ray scattering and nitrogen adsorption isotherms showed that these samples featured ordered mesostructure, high surface area, and narrow pore size distributions. Solid-state (13)C- and (29)Si cross-polarization magic-angle spinning NMR spectra showed chemical linkage between amine-containing modifiers and the surface of mesoporous materials. The chemically linked amine-containing modifiers were found to be on both the inner and outer surfaces. N-[3-(trimethoxysilyl)propyl]ethylenediamine-modified BPMO (A2-BPMO) sample exhibited the highest CO2 uptake (i.e., ∼3.03 mmol/g measured on a volumetric adsorption analyzer) and the fastest adsorption rate (i.e., ∼13 min to attain 90% of the maximum amount) among all the samples studied. Selectivity and reproducibility measurements for the A2-BPMO sample showed quite good performance in flowing N2 gas at 40 mL/min and CO2 gas of 60 mL/min at 25 °C.

Solution processable bilayered gate dielectric towards flexible organic thin film transistors

In this study, we have successfully explored the potential of a new bilayer gate dielectric material, composed of Polystyrene (PS), Pluronic P123 Block Copolymer Surfactant (P123) composite thin film and Polyacrylonitrile (PAN) through fabrication of metal insulator metal (MIM) capacitor devices and organic thin film transistors (OTFTs). The conditions for fabrication of PAN and PS-P123 as a bilayer dielectric material are optimized before employing it further as a gate dielectric in OTFTs. Simple solution processable techniques are applied to deposit PAN and PS-P123 as a bilayer dielectric layer on Polyimide (PI) substrates. Contact angle study is further performed to explore the surface property of this bilayer polymer gate dielectric material. This new bilayer dielectric having a k value of 3.7 intermediate to that of PS-P123 composite thin film dielectric (k∼2.8) and PAN dielectric (k∼5.5) has successfully acted as a buffer layer by preventing the direct contact between the organic semiconducting layer and high k PAN dielectric. The OTFT devices based on α,ω-dihexylquaterthiophene (DH4T) incorporated with this bilayer dielectric, has demonstrated a hole mobility of 1.37×10−2 and on/off current ratio of 103 which is one of the good values as reported before. Several bending conditions are applied, to explore the charge carrier hopping mechanism involved in deterioration of electrical properties of these OTFTs. Additionally, the electrical performance of OTFTs, which are exposed to open atmosphere for five days, can be interestingly recovered by means of re-baking them respectively at 90°C.

Synthesis of micro/mesoporous silica material by dual-template method as a heterogeneous catalyst support for alkylation

A series of micro/mesoporous composites were synthesized using non-ionic block copolymer Pluronic P123 and protic ionic liquid (triethylamine acetate) as the co-templates.

Effect of cosolvents on the self-assembly of a non-ionic polyethylene oxide–polypropylene oxide–polyethylene oxide block copolymer in the protic ionic liquid ethylammonium nitrate

The effect of water and methanol on the self-assembled structures formed by the polyethylene oxide–polypropylene oxide–polyethylene oxide block copolymer Pluronic P123 in ethylammonium nitrate was investigated by small angle X-ray scattering (SAXS). Two ternary phase diagrams were established. The addition of water had only a minor effect on the liquid crystal structures, however methanol had a significant effect, which was attributed to methanol being a good solvent for both the PEO and PPO blocks of the polymer. No lyotropic liquid crystal phases were retained when methanol reached 25wt%. The phase behaviour did not change significantly over the temperature range from 25 to 45°C.

Preparation, optimization, characterization and cytotoxicity in vitro of Baicalin-loaded mixed micelles

The aim of this study was to develop a Baicalin (BC)-loaded mixed micelle delivery system (BC–ST–P123–MMs) with sodium taurocholate (ST) and pluronic P123 block copolymer (P123) as carrier materials to improve the solubility of BC, a poorly soluble drug. In this study, the mixed micelle system was prepared using the method of thin-film dispersion and then optimized by the homogeneous design–response surface methodology with the entrapment efficiency and drug loading as indexes. The average size and the zeta potential of the BC–ST–P123–MMs were 15.60nm and −5.26mV, respectively. Drug loading (DL, 16.94%) and entrapment efficiency (EE, 90.67%) contributed to high solubility (10.20mg/mL) of BC in water. The optimized BC–ST–P123–MMs appeared spherical with obvious core–shell structure and well dispersed without aggregation and adhesion under TEM. In addition, DSC result indicated that BC had been wrapped in BC–ST–P123–MMs and crystalline state of BC was changed. The release result in vitro showed that BC–ST–P123–MMs presented sustained release behavior compared to control group. The IC50 value of BC–ST–P123–MMs (46.18μg/mL) was lower than that of BC solution (67.14μg/mL) on Hep G2 cell lines. Cellular uptake tests illustrated that the ST–P123–MMs system as carrier could significantly enhance the uptake of drugs by tumor cells. The results demonstrated that the BC-loaded mixed micelles could improve solubility of BC and exhibited great potential for delivering drug into cancer cells.