Piranha Solution Research Articles

Thermal Conductance of Epoxy/Alumina Interfaces

The interfacial thermal conductance (ITC) between filler and polymer matrix is considered as one of the important factors that limits the thermal conductivity of thermally conductive polymer composites. The effect of two different surface treatments (piranha solution and plasma) on ITC of epoxy/alumina was investigated using Time-domain thermoreflectance method (TDTR). The TDTR results show that compared with non-treated samples, the ITC of samples treated by piranha solution and plasma increased 2.9 times and 3.4 times, respectively. This study provides guidance for improving the thermal conductivity of thermally conductive polymer composites.

Surface modification and antibacterial properties of superelastic Ti-Zr-based alloys for medical application

To date, significant progress has been achieved in the development of biomedical superelastic Ti-based alloys with high mechanical properties. In view of the high probability of implant-associated infection, an urgent task is to impart bactericidal properties to the material. Herein, advanced superelastic Ti-18Zr-15Nb alloys were surface-etched in a piranha solution, and then Ag nanoparticles were deposited on their surface using a polyol process. This led to the formation of a porous surface layer with a thickness of approximately 100 nm and pore size of less than 20 nm, filled with metallic Ag nanoparticles with an average size of 14 nm. The surface-modified samples showed superior antibacterial activity against E.coli cells. The enhanced bactericidal efficiency is explained by the combination of a higher rate of Ag+ ions release and direct contact of E.coli cells with Ag nanoparticles.

Alumina and Zirconia-Reinforced Polyamide PA-12 Composites for Biomedical Additive Manufacturing.

This work aimed to prepare a composite with a polyamide (PA) matrix and surface-modified ZrO2 or Al2O3 to be used as ceramic fillers (CFs). Those composites contained 30 wt.% ceramic powder to 70 wt.% polymer. Possible applications for this type of composite include bioengineering applications especially in the fields of dental prosthetics and orthopaedics. The ceramic fillers were subjected to chemical surface modification with Piranha Solution and suspension in 10 M sodium hydroxide and Si3N4 to achieve the highest possible surface development and to introduce additional functional groups. This was to improve the bonding between the CFs and the polymer matrix. Both CFs were examined for particle size distribution (PSD), functional groups (FTIR), chemical composition (XPS), phase composition (XRD), and morphology and chemical composition (SEM/EDS). Filaments were created from the powders prepared in this way and were then used for 3D FDM printing. Samples were subjected to mechanical tests (tensility, hardness) and soaking tests in a high-pressure autoclave in artificial saliva for 14, 21, and 29 days.

Graphene effects on the structural, morphological and optical properties of PEDOT:PSS thin films

In this work, nanocomposite polymeric films were fabricated by spin coating technique on the pre-treated glass substrate for sensors application. nanocomposites consist of PEDOT:PSS polymer as a matrix phase and Graphene with different weight percentages (0.5, 1, 1.5, 2) wt% as a dispersion phase. To enhance its surface reactivity, glass substrate were etched chemically using Piranha Solution. FTIR results showed there is no chemical reaction occurred, just only hydrogen bonding arises among components. The mechanism of the proposed model suggested that the interaction achieved by three steps. XRD results showed that, with the Graphene content, the diffraction position shifted upward; from 2θ = 24° to 2θ = 26°, as well as the intensity increased. All crystalline parameters, which either derived from Bragg's Law or from Scherer's equation proved the Graphene dispersion and the increment of the crystallinity. AFM results showed that roughness increased by about 92% through the roughness average (Sa) parameter and by 45% through the density of summits (Sds) parameter. These finding matched with the SEM images, which showed that, the PEDOT:PSS films without Graphene has a comparatively smoother surface than the PEDOT: PSS with Graphene and this confirms that the mechanical strength of the prepared films improved clearly and significantly. UV‐ VIS Spectroscopy results proved that Graphene addition increased the absorbance in UV, VIS, and IR regions, and the absorbance in the UV region is higher than the other two regions, which indicates that the prepared film resists UV- degradation.

Simple Approach to Medical Grade Alumina and Zirconia Ceramics Surface Alteration via Acid Etching Treatment

In order for bioceramics to be further used in composites and their applications, it is important to change the surface so that the inert material is ready to interact with another material. Medical grade alumina and zirconia ceramic powders have been chemically etched with three selected acidic mixtures. Powder samples were taken for characterization, which was the key to evaluating a successful surface change. Changes in morphology, together with chemical composition, were studied using scanning electron microscopy, phase composition using X-ray diffraction methods, and nitrogen adsorption/desorption isotherms are used to evaluate specific surface area and porosity. The application of HF negatively affected the morphology of the material and caused agglomeration. The most effective modification of ceramic powders was the application of a piranha solution to obtain a new surface and a satisfactory degree of agglomeration. The prepared micro-roughness of the etched ceramic would provide an improved surface of the material either for its next step of incorporation into the selected matrix or to directly aid in the attachment and proliferation of osteoblast cells.

Permeability enhancement of chemically modified and grafted polyamide layer of thin-film composite membranes for biogas upgrading

Membrane separations enable biogas upgrading, but their energy efficiency must still be improved for industrial upscaling. Nevertheless, UV treatment affects the permeation properties of the polyamide functional layer of reverse osmosis (RO) and nanofiltration thin film composite (TFC) membranes. In this work, after membrane activation via Piranha solution, cysteamine grafting and UV irradiation, we determined the gas permeability of dry and swelled samples. The samples exhibited higher permeability to gases (CO2, CH4 and N2) than pristine membranes, reaching a 100% increase in RO membranes grafted with cysteamine after UV activation. Permeability increased more than twofold compared to TFC RO membranes activated by diode discharge plasma, as recently reported. Separation favored smaller gas molecules, and the increase in permeability resulting from all modifications did not adversely affect selectivity. CO2/CH4 selectivity remained almost constant over the range of trans-membrane pressure difference to 400 kPa. The grafting with cysteamine to the activated functional layer at the RO membrane positively affected permeability despite the detrimental effect of activation with a Piranha solution. The same activation or cysteamine grafting method at the nanofiltration membrane led only to a very short operation time, although the pristine nanofiltration membrane was stable. The pristine nanofiltration membrane were less permeable to all gasses than all RO membranes. Mixed gas separation of model binary biogas mixtures enhanced CH4 and CO2 permeability only in membranes activated with UV radiation. Decrease of mixed gas selectivity with the growing feed pressure showed that the gas mixture is more effectively separated at lower trans-membrane pressures. Therefore, our model for describing gas mixture separations in cylindrical permeation cells can be utilized to better evaluate the mass transfer coefficient and assess the strength of the coupling effect.

Solvent-processable 0D covalent organic framework quantum dot engineered composite membranes for biogas upgrading

COF (covalent organic framework)-based composite membranes offer the opportunity for breakthroughs in separation performance through endowing COFs with easy film-forming properties. However, tough challenges of poor filler dispersity, limited functionality and interfacial compatibility severely restrict the development of COF-based composite membranes. Therefore, the careful design of physical and chemical structures for COFs is urgently needed. Here, a geometry transformation strategy, i.e. converting FCTF-1 (fluorinated covalent triazine frameworks) from 2D nanosheets to 0D quantum dots (QDs), is implemented to overcome some of the challenges. The greatly decreased filler size increases the solvent dispersibility and processability of FCTF-1 quantum dots (QD-FCTF-1), giving rise to thorough mixing between the polymer matrix and quantum dot filler. Apart from the changes in physical characteristics of filler, the geometry transformation using piranha solution introduces chemical functionality at the quantum dot edges, further strengthens the interfacial compatibility through the hydrogen bond interactions between polar hydroxy and amidine groups of QD-FCTF-1 and nitrile groups of PIM-1 (polymer of intrinsic microporosity). Moreover, these edge polar groups intensify favorable gas sorption due to their high affinity to CO2 molecules and thus significantly improve membrane gas pair selectivity. This work broadens the scope of framework-based materials and offers a new avenue for molecular separation.

Surface Bioactivation of Polyether Ether Ketone (PEEK) by Sulfuric Acid and Piranha Solution: Influence of the Modification Route in Capacity for Inducing Cell Growth.

The aim of this study was to promote bioactivity of the PEEK surface using sulfuric acid and piranha solution. PEEK was functionalized by a sulfuric acid treatment for 90 s and by piranha solution for 60 and 90 s. Chemical modification of the PEEK surface was evaluated by infrared spectroscopy, contact angle analysis, cytotoxicity, cell adhesion and proliferation. The spectroscopy characteristic band associated with sulfonation was observed in all treated samples. PEEK with piranha solution 60 s showed an increase in the intensity of the bands, which was even more significant for the longer treatment (90 s). The introduction of the sulfonic acid functional group reduced the contact angle. In cytotoxicity assays, for all treatments, the number of viable cells was higher when compared to those of untreated PEEK. PEEK treated with sulfuric acid and piranha solution for 60 s were the treatments that showed the highest percentage of cell viability with no statistically significant differences between them. The modified surfaces had a greater capacity for inducing cell growth, indicative of effective cell adhesion and proliferation. The proposed chemical modifications are promising for the functionalization of PEEK-based implants, as they were effective in promoting bioactivation of the PEEK surface and in stimulating cell growth and proliferation.

Investigation and optimization of HfO2 gate dielectric on N-polar GaN: Impact of surface treatments, deposition, and annealing conditions

UV-assisted capacitance–voltage (C–V) and current–voltage (I–V) measurements were performed on ∼20 nm HfO2/GaN metal–insulator–semiconductor capacitors. The effects of surface preparation, predeposition treatment, HfO2 deposition process, and post-deposition annealing environment on interface characteristics were studied. Surface preparation by etching in diluted BHF and piranha etch prior to atomic layer deposition (ALD) suppressed the interface states compared to the baseline sample possibly due to the removal of the native oxide and impurities. UV/ozone treatment prior to HfO2 deposition reduced the interface states by one order of magnitude compared to the baseline sample possibly due to the formation of a thin Ga2O3 interlayer. In situ ALD pretreatment with tri-methyl-aluminum/N2 plasma was also found to reduce the surface states significantly compared to the baseline sample. In addition, thermal ALD improved the dielectric constant and breakdown voltage of the dielectric as compared to plasma ALD due to less surface damage. The lowest average interface trap density achieved was 1.64 × 1012 cm−2/eV with an HfO2 dielectric constant of 16 on the sample with UV/ozone and piranha treatment with in situ ALD treatment and thermal ALD deposition.

Effects of Proppant Wettability and Size on Transport and Retention of Coal Fines in Saturated Proppant Packs: Experimental and Theoretical Studies

Hydraulic fracturing is the main stimulation technique that enables the economic production of coalbed methane reservoirs. However, massive invasion and retention of coal fines in proppant packs can clog the pore spaces and lead to an impairment of fracture conductivity. In this study, the effects of proppant wettability and size on retention of coal fines in proppant packs during the dewatering stage were investigated, for their optimization to achieve a long-term and effective control of fines retention. First, a series of transport and retention experiments of coal fines were performed on saturated proppant packs with different proppant sizes and wettabilities. Herein, standard quartz sand was used as the proppant carrier, and its surface wettability was modified to either hydrophobicity or stronger hydrophilicity by treatment with fluorocarbon resin and piranha solution, respectively. The experimental results indicated that both the retained amount and the deposition rate coefficient of coal fines decreased with increasing proppant hydrophilicity (or decreasing proppant hydrophobicity) and size. For the proppants treated with piranha solution, almost no coal fines were retained in proppant packs. Second, the forces/torques acting on coal fines in the vicinity of proppants were analyzed to elucidate the underlying mechanisms responsible for the influence of proppant wettability and size on fines retention. The effective filter surface (EFS) parameter was estimated by analyzing forces/torques to evaluate the filtration performance of proppant packs. Theoretical results illustrated that the EFS value decreased with increasing proppant hydrophilicity and size. The EFS value for proppants treated with piranha solution was near zero, which was due to the chemically “unfavorable” retention condition induced by piranha solution treatment. The EFS exhibited a similar tendency to the retention of coal fines observed in experiments, which validated the model. Finally, the recommendations on fines retention control in proppant packs were provided.

Influence of chemical etching on bond strength of translucent zirconia to resin cement

Purpose: To assess the effect of chemical pre-treatments (piranha, hot acid, and heteropolyacid) on the bond strength (μTBS) to zirconia. Materials and Methods: A total of 8 sintered zirconia blocks were randomly assigned into 4 groups; Group I: Air abrasion, Group II: Air abrasion and etching using piranha solution (3H2SO4: 1H2O2), Group III: Air abrasion and etching using hot acid solution (1HNO3: 1HF), and Group IV: Air abrasion and etching using heteropolyacid solution (2gm/50 mL). Zirconia blocks were bonded to their corresponding pre-constructed composite blocks using adhesive resin cement. For each group, each assembly was sectioned to obtain 20 microbars. All microbars were thermocyled (10,000), then the μTBS test was done with the aid of a Universal Testing machine. To determine the mode of failure, each specimen was examined under stereomicroscope (x40). One-way ANOVA and Post Hoc Tukey tests were used. Results: The piranha pre-treatment displayed the lowest bond strength (16.82 ±5.97 MPa), while heteropolyacid pre-treatment had higher bond strength (26.22 ±4.05 MPa). One-way ANOVA test indicated statistical significant difference between the studied groups (P<.001). No significant difference was observed between control and piranha groups, also between hot acid and heteropolyacid groups. However, there were statistical significant difference between the control and heteropolyacid groups, and between piranha and heteropolyacid groups. Conclusions: According to the current findings; The novel surface pre-treatment with heteropolyacid (2gm/50 mL) performed well to improve bonding to air-abraded zirconia-based ceramics. The hot acids etching pre-treatment enhanced the bonding to zirconia.

Effects of surface oxidation on the pH-dependent surface charge of oxidized aluminum gallium nitride

Hypothesis: The properties of the oxidized surface for common materials, such as silicon and titanium, are known to be markedly different from the reduced surface. We hypothesize that surface-oxidized aluminum gallium nitride ((oxidized-AlGaN)/GaN) surface charge behavior is different to unoxidized AlGaN (with ultrathin native oxide only), which can be validated via surfactant adsorption. Understanding these differences will explain why (oxidized-AlGaN)/GaN-based sensors are better performing than AlGaN ones, which has been previously demonstrated but not understood.Experiments: The surface of an AlGaN/GaN structure was oxidized with hot piranha solution and oxygen plasma. AFM force measurements and imaging were performed to probe the charge properties of the surface in aqueous solutions of varying pH containing only an acid or base, or with an added ionic surfactant: cationic cetyltrimethylammonium bromide (CTAB) or anionic sodium dodecylsulfate (SDS).Findings: The (oxidized-AlGaN)/GaN surface is positively charged at pH 4 and pH 5.5, although pH 5.5 should be close to the isoelectric point of the surface. The surface is negatively charged at pH 10 and pH 12, and sufficiently charged to attract cooperative adsorption of CTAB aggregates at pH 12. At pH 2, the evidence is inconclusive, but the surface is most likely positively charged. Compared to unoxidized AlGaN, the (oxidized-AlGaN)/GaN surface shows a wider range of surface charge magnitude over pH values between 2 and 12. This suggests that the (oxidized-AlGaN)/GaN surface has a higher surface hydroxyl group density than unoxidized AlGaN, which explains the higher sensitivity for pH sensors based on (oxidized-AlGaN)/GaN structures.

Oxidized MWCNTs as an Oxidizing Agent and Dopant in MWCNT@Polypyrrole Composite Formation**

AbstractA new approach to the formation of composites of carbon nanotubes and polypyrrole (PPy) is proposed. Oxidized multi‐walled carbon nanotubes (ox‐MWCNTs) are used as oxidation agents in pyrrole polymerization. The polymeric phase is deposited both at the surface of the carbon nanotube to form a core‐shell structure and in the empty spaces of the MWCNT network. Each form of the polypyrrole phase exhibits different electrochemical properties. PPy deposited directly at the carbon nanotube surface as a uniform and dense layer is oxidized at less positive potentials, compared to the polymeric material deposited in the pores of the nanotube network. MWCNTs with anions incorporated into structural defects formed during their oxidation in a piranha solution also act as dopants of the oxidized form of PPy. The polymeric film deposited directly at the ox‐MWCNT surface is in its oxidized state. The redox processes involving this part of the PPy film are accompanied by the transport of cations of the supporting electrolyte. The charge transfer between ox‐MWCNTs and the deposited PPy film is confirmed by the results of the theoretical calculations of the energy states at the carbon nanotube and polypyrrole interface. A neutral PPy film located in layers remote from the surface of the nanotube is oxidized at more positive potentials. The oxidation of PPy located in the pores of the ox‐MWCNT network results in a broad voltammetric peak formation.

Towards prevention of biofilm formation: Ti6Al7Nb modified with nanocomposite layers of chitosan and Ag/Au nanoparticles

Implant-associated infections are the major concern for failure of arthroplasty operations. The functionalisation of implant surface can provide solutions to the problem by either inhibiting the adherence of the bacteria or introducing a contact-killing mechanism. This work is focused on Ti6Al7Nb biomedical alloy modification involving chemical and plasma surface activation, followed by the deposition of chitosan layers enhanced with metal nanoparticles. A benign method using chitosan as an efficient reducing and stabilizing agent was applied to produce Au and Ag nanoparticles in situ with the size of ca. 20 nm and 5 nm, respectively. Piranha solution and O2/NH3/Ar plasma were used as a surface activation method, while Au and AgNPs provide antimicrobial properties, as a viable alternative to the antibiotic-based approach. The surface topography on submicrometre scale of deposited layers was evaluated. Chitosan and chitosan–Ag NPs composite layers showed excellent hydrophilicity, characterised by wetting angles below 13°. Modified alloy showed minimal toxicity towards MG-63 cell line in vitro, acceptable corrosion resistance and release of titanium, aluminium as well as niobium ions from the resulting modified alloys. The chitosan layers were proven to uphold satisfactory Au (over 2.8 mg/dm3) and Ag (over 5.1 mg/dm3) ion dosages up to 96h.

The Control of Intramolecular Through-Bond and Through-Space Coupling in Single-Molecule Junctions

The Control of Intramolecular Through-Bond and Through-Space Coupling in Single-Molecule Junctions

Sol-gel Preparation of Silan based Zirconia Hybrid Thin Film

The sol-gel process is an innovative advanced method, initially developed to synthesize glass and ceramics at low temperature. Sol-gel process can be used to synthesis materials with a variety of shapes, such as porous membranes, thin fibers, nano-size powders and thin films. In this study, epoxy and methacrylate based silane coupling agents are used together with zirconium oxide to form a hybrid coating system on glass surface. In the experimental study, an organic–inorganic molecular hybrid compound was prepared by sol-gel method. First glasses were cleaned by traditional piranha solution (3:1 H2SO4 : H2O2) to remove contaminants. Silanization was applied to increase the adhesion of hybrid coatings on glass substrates. Glass substrate was coated with this solution by a homemade dip-coater. In this study, (3-Glycidoxypropyltrimethoxysilane, GLYMO and 3-(trimethoxysilyl)propylmethacrylate, TMSPM) were chosen as a silane. Zirconia is inorganic component of hybrid materails. Coated samples were characterized by Fouirer Transform Infrared Spectrophotometer (FTIR), Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Contact Angle Goniometer.

Facilitating the formation of SnO2 film via hydroxyl groups for efficient perovskite solar cells

Interfacial engineering has been considered as an effective technique to improve the photovoltaic performance of perovskite solar cells (PSCs). Here, the interface between tin oxide (SnO2) film and fluorine-doped tin oxide (FTO) glass is dealt with a piranha solution, resulting in more hydroxyl groups on the surface of FTO glass. SnO2 film is fabricated by spin-coating SnCl2·2H2O precursor. Our results demonstrate that SnO2 film exhibits high electricalconductivity, low electron trap density, and suitable energy level. Furthermore, SnO2 film with low roughness is beneficial to fabricate high-quality perovskite film. Then, the PSCs with the structure of FTO/SnO2/Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3/Spiro-OMeTAD/Au are also fabricated. The highest power conversion efficiency (PCE) of PSCs increases from 18.28% to 19.51%, and the average PCE enhances from 17.82% to 18.89%. The optimized PSC shows the long-term stability and remains 97% of its initial PCE after 4000 h on-shelf lifetime test.

Adsorption of volatile benzene series compounds by surface-modified glass fibers: kinetics, thermodynamic adsorption efficiencies, and mechanisms.

The presence of volatile benzene series compounds (VBSCs) in the environment is continually increasing, with the potential for negative effects on human health. It is therefore important to develop new materials for the adsorption of these compounds using various modification techniques. Glass fibers are a promising adsorbent for VBSCs and offer a number of advantages. In the present work, the surfaces of glass fibers were modified using hydrogen peroxide, a sodium hydroxide solution, or Piranha solution (a mixture of concentrated sulfuric acid and hydrogen peroxide). The adsorption characteristics of the resulting specimens were investigated, employing 10 volatile benzene-based compounds, and the activated glass fibers showed significantly improved adsorption efficiencies. The fibers activated with the Piranha solution were further modified with a triethoxysilyl benzene compound to obtain an aryl-modified material that demonstrated enhanced adsorption of aniline, salicylaldehyde, benzyl alcohol, and xylene relative to that obtained from a combination of polyurethane foam and XAD-2 resin. The adsorption efficiency of benzyl alcohol by these aryl glass fibers was found to be as high as 93% and the adsorption mechanism is believed to be associated with hydrogen bonding and π-π conjugation. This study provides a reliable technique for the quantification of VBSCs and a basis for the evaluation of various adsorption materials.

High Performance, Eco-Friendly SPM Cleaning Technology Using Integrated Bench-Single Wafer Cleaning System

Batch SPM systems do not meet the current clean specification/requirements below 28nm. Single wafer SPM systems use a high volume of chemistry which runs to drain, while meeting the cleaning specifications below 28nm. The work in this paper describe the use of a batch SPM system and a single wafer clean in an integrated system, Ultra-C Tahoe which results in meeting the technical specification and using less that 80% of the SPM chemistry used in single wafer systems. The data collected shows this new system meet the specifications, whilst saving more than 80%of SPM chemistry.

Incorporation of open-pore MFI zeolite nanosheets in polydimethylsiloxane (PDMS) to isomer-selective mixed matrix membranes

A mixture of H2SO4 and H2O2 (known as piranha solution) was used to remove organic structure-directing agents (OSDA) from multilamellar MFI zeolite (ML-MFI). An aqueous solution of MFI zeolite nanosheets was obtained via exfoliation of the OSDA-free ML-MFI zeolite through sonication in water followed by purification through sedimentation. The exfoliated MFI zeolite nanosheets were characterized by various techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and porosimetry by cryogenic N2 adsorption-desorption, indicating that single-layer MFI nanosheets were obtained and the micropores were opened. MFI nanosheets/polydimethylsiloxane (PDMS) mixed matrix membranes (MMMs) were prepared by the solution casting method using the open-pore MFI zeolite nanosheets as the filler and PDMS as the continuous phase. The obtained MMMs exhibited greatly improved butane isomer permeabilities and ideal selectivities for n-butane over i-butane compared to the pure PDMS membrane. An ideal selectivity of 15.7 for n-butane/i-butane was achieved on the MMM at 1 wt% loading of MFI nanosheets, with a n-butane permeability up to 15615 Barrer.