3-mercaptopropyl Trimethoxysilane Research Articles

Mercapto functionalized–natural zeolites/PVDF mixed matrix membrane for enhanced removal of methylene blue

Azo dye-containing wastewater is one of the most critical contaminants due to modern industrial activities, especially in the textile industry. Membrane technology has been the most prominent separation technique to alleviate these pollutants with less energy input and less raw material utilization. In this sense, zeolite-based mixed matrix membranes have offered increased filtration performance as they combine the favorable properties of polymeric membranes, molecular sieving, and the negative charge properties of zeolites. The crucial challenge is the compatibility of the inorganic filler and the polymer matrix to boost flux and rejection; otherwise, both will be dramatically compensated. Herein, low-cost natural zeolites were functionalized using mercapto silane ((3-mercaptopropyl) trimethoxysilane) agent and incorporated into porous polyvinylidene fluoride (PVDF). The resulting mixed matrix membranes showed significantly higher rejection (97.01%) and flux (37.14 L m−2h−1) compared to those of pristine PVDF membrane (rejection and flux of 82.78% and 24.05 L m−2h−1, respectively). These positive results are due to the compatibility between the mercapto-functionalized natural zeolites and PVDF matrix. In the absence of mercapto groups, the rejection could be enhanced, but the permeability decreased. In addition, the antifouling properties of the mercapto functionalized–natural zeolites/PVDF mixed matrix membrane is desirable, as indicated by the higher flux recovery ratio and lower reversible and irreversible fouling.

Synthesis of Three Novel Silane-Based Carboxylic Acids for Application in Methacrylated Epoxy-Based Oligomers and Their Ability to Improve the Properties of UV Curable Hybrid Coatings

Improvement of thermal stability of silicone-based coatings was the main objective of this study. In this study bromoacetic acid (BAA) was reacted with 3-(mercaptopropyl) trimethoxy silane (MPTS) and trimethoxy silyl propyl thioacetic acid (TSTA) was produced. Also, bromoacetic acid (BAA) was reacted with 3-(triethoxysilyl) propylamine (APTS) and triethoxysilyl propylamino acetic acid (TSPA) was synthesized. Finally, from a reaction between trimellitic anhydride (TMA) and APTS, trimellitylimidopropyl triethoxysilane (TMIS) resulted. Compounds containing carboxylic acids and trimethyl silane were obtained in all of these reactions. Furthermore, hybrid coatings based on methacrylated bisphenol A epoxy (MBAE) and the synthesized carboxylic acids were obtained by photopolymerization. Polycarbonate substrates were utilized for preparation of the transparent hybrid films. Then the solvent resistance, hardness and gel content, as well as the adhesion of the coatings, were measured as physical and mechanical properties. According to the obtained results, these properties of the hybrid coatings were improved with the increase in alkoxysilanes and sol–gel precursor contents. The surface morphology was characterized by scanning electron microscopy (SEM). The results showed that silica particles were not dispersed homogenously at the molecular level in the hybrid system. Also, the thermogravimetric analysis results indicated that alkoxysilanes enhanced the thermal oxidative stability of the hybrid coatings.

Hydrolysis and condensation kinetic studies of mercaptopropyl trimethoxysilane using in-situ Raman spectroscopy

The hydrolysis and condensation kinetic parameters of mercaptopropyl trimethoxysilane (MPTMS, HS(CH2)3Si(OCH3)3) have rarely been quantitatively studied due to the fast reaction rate with the presence of catalysts. In this work, we employed the in-situ Raman spectroscopy to monitor the hydrolysis and condensation reactions of MPTMS in real time. First, with CH3OH as the solvent and NH4OH as the catalyst, the hydrolysis kinetics of MPTMS was investigated via the initial rate method. The reaction orders with respect to MPTMS, H2O, and NH4OH are 1.0, 1.0, and 1.0, respectively. The activation energy (Ea) and pre-exponential factor (A) of MPTMS hydrolysis reaction are (28.4 ± 1.1) kJ/mol and 938.1 (mol/L)-2·min−1, respectively. Then, an ‘acid-catalyzed hydrolysis and base-catalyzed condensation’ two-step strategy was employed to decouple the hydrolysis and condensation reactions. With the hydrolysates, trihydroxy silanols HS(CH2)3Si(OH)3, as the starting reactant, the early-stage condensation reaction kinetics was studied. The reaction orders with respect to HS(CH2)3Si(OH)3 and NH4OH are 1.4 and 2.8, respectively. The activation energy (Ea) and pre-exponential factor (A) of the condensation reaction are (52.2 ± 0.4) kJ/mol and 7.5 × 1013 (mol/L)-3.2·min−1, respectively. The kinetic parameters determined in this work could provide quantitative guidance for the design and control of MPTMS reaction process.

Flexible Humidity Sensor Based on Au Nanoparticles/Organosilica-Containing Polyelectrolyte Composite

A novel flexible humidity sensor incorporating gold nanoparticles (Au NPs) and a trifunctional organosilica compound has been developed through the integration of sol–gel processing, free radical polymerization, and self-assembly techniques. The trifunctional organosilica was initially synthesized by modifying (3-mercaptopropyl)trimethoxysilane (thiol-MPTMS) with 3-(trimethoxysilyl)propyl methacrylate (vinyl-TMSPMA). Subsequently, a hydrophilic polyelectrolyte, [3(methacryloylamino)propyl]trimethyl ammonium chloride (MAPTAC), was grafted onto the MPTMS-TMSPMA gel. The Au NPs were assembled onto the thiol groups present in the MPTMS-TMSPMA-MAPTAC gel network. The compositional and microstructural properties of the Au NPs/MPTMS-TMSPMA-MAPTAC composite film were investigated utilizing Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The presence of thiol groups and mesoporous silica skeletons ensured the stability of the humidity-sensing film on the substrate under highly humid conditions, while the hydrophilic groups functioned as humidity-sensitive sites. This innovative humidity sensor demonstrated high sensitivity, acceptable linearity, minimal hysteresis, and rapid response time across a broad range of working humidity levels. Based on the complex impedance spectra analysis, hydronium ions (H3O+) were determined to govern the conductance process of the flexible humidity sensor.

Improved thermal conductivity of poly(p-phenylene sulfide)/glass fiber composites via addition of polysiloxide-coated aggregated boron oxide and silane-treated graphene oxide

Poly (p-phenylene sulfide) (PPS) is a material with strong mechanical properties and chemical stability. However, PPS has a low thermal conductivity of 0.18 W/m•K, which limits its applications in fields requiring heat dissipation properties. In this work, to improve the mechanical and thermal properties, aggregated boron nitride (ABN) and graphene oxide (GO) fillers were added into the PPS/glass fiber (PPS/GF) system with proper treatment. ABN was covered with amine-functional polysiloxide and heat-treated to withstand and maintain the morphology after the composite molding process. Additionally, GO underwent 3-mercaptopropyl trimethoxysilane (MPTMS) treatment (MGO) to enhance the interface adhesion between the glass fiber filler and PPS matrix. By adding PSZABN and MGO into the PPS/GF system, the mechanical properties, storage modulus, and tensile strength were improved, and the thermal conductivity of the PPS/GF@20PSZABN@10MGO composite was 1.18 W/m•K, which is 6.55 times improved than that of pristine PPS.

Characterization of polar surface groups on siliceous materials by inverse gas chromatography and the enthalpy-entropy compensation effect.

Surface-modified porous silica is a well-established composite material. To improve its embedding and application behavior, adsorption studies of various probe molecules have been performed using the technique of inverse gas chromatography (IGC). For this purpose, IGC experiments were carried out in the infinite dilution mode on macro-porous micro glass spheres before and after surface modification with (3-mercaptopropyl)trimethoxysilane. To provide information about the polar interactions between probe molecules and the silica surface, in particular, eleven polar molecules have been injected. In summary, the free surface energy for pristine silica ( = 229mJ/m2) and for (3-mercaptopropyl)trimethoxysilane-modified silica ( = 135mJ/m2) indicates a reduced wettability after surface modification. This is due to the reduction of the polar component of the free surface energy ( ) from 191mJ/m2 to 105mJ/m2. Simultaneously, with the reduction of surface silanol groups caused by surface modification of silica and, therefore, the decrease in polar interactions, a substantial loss of Lewis acidity was observed by various IGC approaches. Experiments with all silica materials have been conducted at temperatures in the range from 90°C to 120°C to determine the thermodynamic parameters, such as adsorption enthalpy ( ) and adsorption entropy ( ), using the Arrhenius regression procedure evaluating the IGC data. With the help of the enthalpy-entropy compensation, two types of adsorption complexes are assumed between polar probe molecules and the silica surface because of different isokinetic temperatures. Identical adsorption complexes with an isokinetic temperature of 370°C have been assigned to alkanes and weakly interacting polar probes such as benzene, toluene, dichloromethane, and chloroform. Polar probe molecules with typical functional groups such as OH, CO, and CN, having the ability to form hydrogen bonds to the silica surface, exhibit a lower isokinetic temperature of 60°C. Quantum chemical calculations of the probe molecules on a non-hydroxylated and hydroxylated silica cluster supported the formation of hydrogen bonds in the case of a strong polar adsorption complex with a bonding distance of 1.7nm-1.9nm to the silica surface.

An eco-friendly and energy-efficient protocol for the Heck reaction under solar radiation catalyzed by rice husk silica‐anchored cinchonine.Pd nanocomposite

An environmentally friendly and energy-efficient method for the carbon–carbon bond formation via cross-coupling Heck reaction using rice husk silica-anchored cinchonine.Pd nanocomposite as a heterogeneous catalyst under concentrated solar radiation is being reported. In this investigation, first, silica nanoparticles were synthesized using rice husks as available agricultural bioresources. Then, the surface of nano silica was modified by grafting (3-mercaptopropyl) trimethoxysilane, and after that, thiol-ene free radical reaction of its SH groups with alkene function of cinchonine by azobisisobutylonitrile initiator. Finally, the target nanocomposite, nano SiO2-S-Cin.Pd, was created via loading palladium nanoparticles into the mesoporous nanocomposite by its reaction by palladium acetate, followed by ethanol reduction. The structure and morphology of the nano SiO2-S-Cin.Pd nanocomposite was characterized using Fourier transform infrared spectra, X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. The catalytic ability of this nanocomposite was investigated in the arylation of olefins in both concentrated solar radiation and conventional thermal conditions. A comparison of the conventional and CSR methods for C–C bond formation in PEG, showed that the CSR approach is a better alternative route with a high energy-saving strategy. The nanocatalyst is easily removed from the mixture and has been tested on several runs without a loss of catalytic activity. The heterogeneity of the nano SiO2-S-Cin.Pd catalyst was confirmed by hot filtration test. This method has the advantages of simple methodology, easy work-up, high yields, short reaction times, and greener conditions. In addition to convenience, this technology improves product purity and offers economic and environmental benefits.

Improved Salt Spray Resistance of Silver-Plated SiO2 via Self-Assembled Mercapto Inhibitors

Highly conductive fillers are an essential raw material in the fabrication of conductive composites, paste, ink, adhesive, etc. Still, susceptibility to salt spray erosion remains a serious issue for silver-based fillers. Herein, we first prepared highly conductive silver-plated microspherical silica (Ag/pSiO2) through catechol/polyamine surface functionalization and subsequently formed a self-assembled inhibition layer on the surface of Ag/pSiO2 by using (3-mercaptopropyl)trimethoxysilane (KH590) to enhance the salt spray erosion resistance. The results suggested that the self-assembled KH590 greatly improved the salt spray erosion resistance of the Ag/pSiO2. The total shielding effectiveness (SEt) of the composites protected by KH590 was 106 dB after the salt spray erosion, which was even 16 dB higher than that before erosion. In contrast, the SEt of the composites without KH590 decreased significantly from 111 to 76 dB. Further studies revealed that the KH590 inhibitor strongly prevented the penetration of Cl– and subsequently enhanced the salt spray resistance. Considering the facile and effective preparation, this strategy could be applied in large-scale silver-based EMI shielding materials.

Preparation of Composite Hydrogels with Silica Nanoparticles by Photoinitiated Polymerization Reaction

In this study, (3-mercaptopropyl) trimethoxysilane (MPTMS) modified silica nanoparticles (SiO2-MPTMS) were successfully prepared. The average size of SiO2-MPTMS nanoparticles was measured by Dynamic Light Scattering (DLS) as 341 nm in ethanol, while Scanning Transmission Electron Microscopy (STEM) analyzes confirmed that the nanoparticles were nano-sized and revealed that their shapes were spherical. Then, 3D nanocomposite hydrogels were prepared by incorporating SiO2-MPTMS nanoparticles in various ratios (0.25, 0.50, 0.75 and 1.0 wt %) into an acrylate resin consisting of N-isopropyl acrylamide (NIPAM) and polyethylene glychol diacrylate (PEGDA; as a crosslinker) by the photoinitiated polymerization reaction with Dimethoxy-2-phenylacetophenone (DMPA; as a photoinitiator). By Thermal Gravimetric Analyzer (TGA) measurements, it was determined that the nanocomposite hydrogels maintained their thermal stability up to 330 0C and the thermal degradation steps were close to each other. Scanning Electron Microscopy (SEM) study showed that the neat and nanocomposite hydrogels’ morphological structures were in the porous and smooth scaffold, and also that the SiO2-MPTMS nanoparticles (0.50 wt %) were homogeneously distributed in the network structures of hydrogels, localized in the bonds.

Synthesis and Characterization of Zirconia-Silica PMMA Nanocomposite for Endodontic Implants.

This study aimed to enhance the mechanical properties of PMMA composites by introducing various types of fillers, including ZrO2, SiO2, and a mixture of ZrO2-SiO2 nanoparticles, which were prepared as prototypes for an endodontic implant. The ZrO2, SiO2, and mixed ZrO2-SiO2 nanoparticles were synthesized using the sol-gel method and the precursors Tetraethyl Orthosilicate, Zirconium Oxychloride, and a mixture of both precursors, respectively. Before polymerization, the as-synthesized powders were subjected to the bead milling process to obtain a well-dispersed suspension. Two scenarios for the fillers were implemented in the preparation of the PMMA composite: a mixture of ZrO2/SiO2 and ZrO2-SiO2 mixed with two different types of silane: (3-Mercaptopropyl) trimethoxysilane (MPTS) and 3-(Trimethoxysilyl) Propyl Methacrylate (TMSPMA). The observation of the characteristics of all of the investigated fillers included the use of a particle-size analyzer (PSA), a Zeta-potential analyzer, FTIR, XRF, XRD, and SEM. The mechanical properties of the MMA composites, as prepared under various scenarios, were observed in terms of their flexural strength, diametrical tensile strength (DTS), and modulus of elasticity (ME). These levels of performance were compared with a PMMA-only polymer. Each sample was measured five times for flexural strength, DTS, and ME. The results showed that the best PMMA composite was SiO2/ZrO2/TMSPMA, as revealed by measurements of the flexural strength, DTS, and ME corresponding to 152.7 ± 13.0 MPa, 51.2 ± 0.6 MPa, and 9272.8 ± 2481.4 MPa, which are close to the mechanical properties of dentin. The viability of these PMMA composites, as measured up to day 7, was 93.61%, indicating that they are nontoxic biomaterials. Therefore, it was concluded that the PMMA composite created with SiO2/ZrO2/TMSPMA can be considered to be an acceptable endodontic implant.

Sensitivity enhancement of gold nanospheres assisted CO2 laser tapered optical fiber for refractive index sensor

Tapered optical fibers (TOFs) have been intensively used as sensors due to their high sensitivity, simple structure, and excellent coupling efficiency. In this paper, we reported the successful rapid tapering of single mode and multimode fibers using CO2 laser beam at working wavelength of 10.6 μm. Clean and symmetric tapers could be produced in just 5 s using this method. Arduino-based microcontroller was included in the tapering set-up to precisely control the fiber pulling speed and distance. Smaller waist diameters that were observed in multimode than in single mode fibers generated more evanescent waves on the cladding of tapered multimode fibers (TMMFs). This implied that TMMFs performed better refractive index (RI) sensitivity, within the range of 1.3325–1.4266, than tapered single mode fibers (TSMFs). Furthermore, localized surface plasmon resonance (LSPR) effect was coupled with evanescent wave through AuNSs immobilization on the TOF surface. The AuNSs having average particle diameter of 12.70 nm was synthesized by citrate reduction route. The formation of AuNSs was confirmed by (ultraviolet–visible) UV–vis and high-resolution transmission electron microscopy (HRTEM) data. Self-assembly monolayer approach was conducted to immobilize AuNSs on the 3-mercaptopropyl trimethoxysilane (MPTMS)-functionalized surface of the TOFs. The AuNSs immobilization on TMMFs could improve the sensitivity up to 122 %. Besides sensitive to RI changes, the sensors were also excellent in terms of repeatability and reversibility performances. Finally, this paper described the amplitude modality-based RI sensing mechanism due to evanescent wave and LSPR effects.

Robust superhydrophobic magnetic melamine sponge inspired by lotus leaf surface for efficient continuous oil–water separation

Inspired by the oily surface layer and hierarchical structure on the lotus leaf surface, a magnetic sponge with robust superhydrophobicity (water contact angle up to 155°) and surface protection was synthesized by one-pot solvothermal method by introducing (3-Mercaptopropyl)trimethoxysilane into the melamine sponge. After hydrolysis and self-polymerization, (3-Mercaptopropyl)trimethoxysilane can grow as a low surface energy polysiloxane coating on the surface of sponges and magnetic particles. It not only provides a hydrophobic surface layer for sponges, but also this cooperation of micro-submicron-nanostructure from micron sponge skeleton, submicron Fe3O4 particles and nanoscale polysiloxane builds rough surfaces at multiple scales. Based on the triadic Koch curve model, the theory of superhydrophobic surface is elucidated in detail from the surface fractal behavior, fractal dimension, and surface composition. The sponge can be integrated into a negative pressure system as a filter element for continuous and efficient oil–water separation. The formed polysiloxane can not only provide protection for the sponge skeleton and magnetic particles, but also provide strong cross-linking between the two materials, which can effectively resist the damage to the functional structure caused by oil erosion. In addition, a conceptual diagram of a portable oil suction device similar to a vacuum cleaner was proposed. Combining the basic theory of robust superhydrophobic surface and innovatively clarifying the influence of filter element structure on oil–water separation efficiency from the perspective of interface force, it is expected to bring more practical and potential ideas for the design of a portable vacuum cleaner-like oil–water separation device.

Surface Modification of Silica Particles with Adhesive Functional Groups or Their Coating with Chitosan to Improve the Retention of Toothpastes in the Mouth.

Silica is widely used in the oral care formulations to act as an abrasive and to give the products its distinct physical properties. In this study, silica particles were synthesized using a co-condensation of tetraethyl orthosilicate with a series of functional silane compounds [(3-mercaptopropyl)trimethoxysilane, (3-glycidyloxypropyl)trimethoxysilane, and (3-acryloxypropyl)trimethoxysilane)]. The surface of the particles based on tetraethyl orthosilicate and (3-glycidyloxypropyl)trimethoxysilane was then further modified with 3-aminophenylboronic acid. Commercial Aerosil R972 Pharma silica particles were also coated with chitosan. Additionally, commercially available (3-maleimido)propyl-functionalized silica particles were used in this study. All these functionalized silica particles were incorporated into toothpaste formulations, and their retentive properties were tested on ex vivo sheep tongue mucosa models using fluorescent microscopy-based flow-through techniques. Those surfaces with chitosan, phenylboronic acid, and acryloyl groups were shown to provide a significant improvement in the retention of the oral care formulations during the retention testing. The retention of toothpastes containing silica functionalized with maleimide and thiol groups was also superior compared to that of unmodified silica particles. This study synthesized and tested a range of silica particles and demonstrated that the functionalized silica incorporated into toothpastes can significantly improve the retention of these formulations on oral mucosal surfaces.

Durability of model degraded wood treated with organosilicon compounds against fungal decay

Conservation agents used to preserve heavily degraded wooden artefacts typically act as consolidants that restore the structural integrity of an object. However, treatments that can provide both dimensional stability and improved resistance to wood-decaying organisms are desirable because even degraded wood is still susceptible to further biodegradation. Some organosilicon compounds proved effective at stabilising waterlogged wood dimensions and could serve as potential multi-purpose conservation agents. To assess whether these chemicals can also impart decay and resistance to filamentous fungi, degraded model Scots pine wood was impregnated with three different organosilicon compounds: Methyltrimethoxysilane – MTMS, (3-Mercaptopropyl) trimethoxysilane – MPTMS, and Bis(diethylamino)-3-propoxypropanol)-1,1,3,3-tetramethyldisiloxane – DEAPTMDS), and moisture properties and durability of the treated wood were measured. All three organosilicons reduced treated pine hygroscopicity and provided various degrees of protection against brown-rot and white-rot fungi. However, only DEAPTMDS completely inhibited the growth of filamentous fungi after four weeks of incubation. The results show that tested organosilicons are suitable multi-purpose conservation agents for degraded wooden objects such as waterlogged archaeological wood because they can both consolidate and protect degraded wood from further biodeterioration.

One pot synthesis of thiol-functional nanoparticles

Polysorbate 80 (PS80) was reacted with 3-mercaptopropyl trimethoxysilane (SiSH) via a photoinitiated thiol-ene reaction. The resulting conjugate was co-condensed with SiSH to form stable aqueous solutions of thiol-functional nanoparticles (TFNs).

Fabrication and evaluation of dodecyl imide maleopimaric acid glycidyl methacrylate ester modified silica with multiple retention mechanisms for reversed phase liquid chromatography

As green, less toxic, and abundant ligands with rich functional groups, natural products are widely used in synthesis of chromatographic stationary phases. In this work, dodecyl imide maleopimaric acid glycidyl methacrylate ester (C12-MPAGN) was prepared from maleopimaric acid through the imidization and ring-opening based esterification reaction. By using “thiol-ene” click chemistry, it was chemically bonded to the silica and (3-mercaptopropyl) trimethoxysilane (γ-MPS) was used as the coupling agent to obtain dodecyl imide maleopimaric acid glycidyl methacrylate ester bonded silica stationary phase (Sil-C12-MPAGN). Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopies (SEM), and elemental analysis (EA) were utilized to verify that the Sil-C12-MPAGN stationary phase was successfully prepared with C12-MPAGN immobilized on the silica surface. In order to evaluate the chromatographic performance and retention mechanisms of the Sil-C12-MPAGN column and compared with C18 column, a variety of compounds were used, including stander mixture of Tanaka, alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), phenols and flavonoids. Based on these multiple interactions, including hydrophobic, hydrogen-bonding, and π-π interactions, high selectivity and superior separation performance were demonstrated by the Sil-C12-MPAGN column for probe molecules what had previously been mentioned. In addition, the quantitative determination of paclitaxel content in Yew bark extract was conducted with this column, which was found that the concentration was 83.67 mg/L, respectively. In short, the present study proposes a new strategy for introducing rosin to liquid chromatography with high selectivity and separation performance.

Fabrication of Woven Jute Fiber Epoxy Bio-Composites through the Epoxy/Thiol-Ene Photopolymerization Technique

An eco-friendly epoxy/thiol-ene photopolymerization (ETEP) process was employed to prepare epoxy bio-composites using a commercial biobased epoxy resin and a woven jute fabric as reinforcement. In this process the components of the thiol-ene system, an allyl-functionalized ditertiary amine curing agent, a multifunctional thiol and a radical photoinitiator, were added to the epoxy resin to produce a polyether-polythioether crosslinked co-network. Moreover, the jute fibers were functionalized with thiol groups using the 3-mercaptopropyl (trimethoxysilane) with the purpose of creating a chemically bonded polymeric matrix/fiber system. The obtained bio-composites prepared with the thiol-functionalized cellulose fibers exhibited an increase up to 52% and 40% in flexural modulus and strength with respect to the non-functionalized counterparts. Under the three-point bending loadings, the composites displayed higher deformation at break and toughness due to the presence of polythioethers in the co-network. The prepared bio-composites developed in this work are excellent candidates to extend the use of cellulose fibers for structural applications.

One pot synthesis of hybrid silica aerogels with improved mechanical properties and heavy metal adsorption: Synergistic effect of in situ epoxy-thiol polymerization and sol-gel process

Hybrid material features strongly depend on the synergy between the individual components used during synthesis. To address the current challenges preventing silica aerogels from serving as potential candidates in sustainable chemistry and engineering, we used a novel in situ sulfur-doping synthesis method for silica aerogels to improve the mechanical strength and heavy metal ion adsorption. In this study, three-dimensional monolithic silica aerogels were synthesized using an adaptable one-pot epoxy–thiol reaction to polymerize (3-glycidyloxypropyl)trimethoxysilane and (3-mercaptopropyl)trimethoxysilane, followed by the sol–gel process and supercritical drying. The synergy between the epoxy and thiol groups in the silane precursors with an optimized precursor-to-solvent ratio is crucial for enhancing compressive strength. The cross-linked aerogels had a strong silica hybrid network with high porosity (∼85%–91%), comparable bulk density, and high compressive modulus (∼6.3–20.81 MPa, which is over three orders of magnitude higher than that of traditional tetraethoxysilane-based silica aerogels). The prepared aerogels were then used to remove heavy metals, with Pd2+ being adsorbed approximately 100% of the time. The maximum adsorption capacity fitted using the Langmuir adsorption model was 689.65 mg/g. The proposed method offers a new strategy for synthesizing in situ sulfur-doped silica aerogels with enhanced mechanical properties for heavy metal removal.

Influence of sulfonated SBA - 15 on fuel cell performance of sulfonated polysulfone electrolyte membranes

The prepared mesoporous SBA-15 (Santa Barbara Amorphous-15) was sulfonated and used as filler for the preparation of sulfonated polysulfone based composite electrolyte membranes. The SBA-15 and polysulfone were sulfonated using 3-mercaptopropyl trimethoxysilane and trimethylsilyl chlorosulfonate, respectively. The different weight percentages (1, 3, and 5 wt%) of sulfonated SBA-15 (SSBA-15) were used to prepare composite electrolyte membranes. Water uptake, ion exchange capacity, swelling ratio and proton conductivity of the composite membranes were studied for assessing the suitability of the electrolyte membranes for use in fuel cells. Characterization techniques such as FT-IR, XRD, SEM, TEM and Brunauer–Emmett– Teller were used to study the physico-chemical properties of the electrolyte membranes. TEM and BET analysis showed that SBA -15 retained its mesoporous structure even after sulfonation process. The prepared membranes were then tested in an in-house built single-cell fuel cell using hydrogen as fuel and oxygen as the oxidant. The fuel cell study showed that the presence of Sulfonated SBA-15 in the polymer matrix provided additional ion exchange sites and retained water for proton transfer which resulted in higher power density of 815 mW/cm2 with SPSU + 3% SSBA-15 membrane as compared with Nafion 117®.

Facile and Compact Electrochemical Paper-Based Analytical Device for Point-of-Care Diagnostic of Dual Carcinogen Oxidative Stress Biomarkers through a Molecularly Imprinted Polymer Coated on Graphene Quantum-Dot Capped Gold.

Nanoscale imprinting significantly increases the specific surface area and recognition capabilities of a molecularly imprinted polymer by improving accessibility to analytes, binding kinetics, and template removal. Herein, we present a novel synthetic route for a dual molecularly imprinted polymer (dual-MIP) of the carcinogen oxidative stress biomarkers 3-nitrotyrosine (3-NT) and 4-nitroquinolin-N-oxide (4-NQO) as coatings on graphene quantum-dot capped gold nanoparticles (GQDs-AuNPs). The dual-MIP was successfully coated on the GQDs-AuNPs core via a (3-mercaptopropyl) trimethoxysilane (MPTMS) linkage and copolymerization with the 3-aminopropyltriethoxysilane (APTMS) functional monomer. In addition, we fabricated a facile and compact three-dimensional electrochemical paper-based analytical device (3D-ePAD) for the simultaneous determination of the dual biomarkers using a GQDs-AuNPs@dual-MIP-modified graphene electrode (GQDs-AuNPs@dual-MIP/SPGE). The developed dual-MIP device provides greatly enhanced electrochemical signal amplification due to the improved electrode-specific surface area, electrocatalytic activity, and the inclusion of large numbers of dual-imprinted sites for 3-NT and 4-NQO detection. Quantitative analysis used square wave voltammetry, with an oxidation current appearing at -0.10 V for 4-NQO and +0.78 V for 3-NT. The dual-MIP sensor revealed excellent linear dynamic ranges of 0.01 to 500 μM for 3-NT and 0.005 to 250 μM for 4-NQO, with detection limits in nanomolar levels for both biomarkers. Furthermore, the dual-MIP sensor for the simultaneous determination of 3-NT and 4-NQO provides high accuracy and precision, with no evidence of interference from urine, serum, or whole blood samples.