The effect of the addition of additives such as melamine (Mel), silica nanoparticles and a phosphorus-based compound, i.e. 3-(6-oxidodibenzoc,e1,2oxaphosphinin-6-yl)propenamide (DA), on the fire and ...mechanical performance of a bisphenol A diglycidyl ether (DGEBA)-based epoxy resin cured with isophoronediamine has been investigated. A UL 94-V0 classification was achieved for epoxy resin containing DA at 2 wt% of phosphorus loading. However, addition of silica nano particles was necessary to avoid melt dripping. The incorporation of DA and Mel to the epoxy resin promoted a remarkable reduction (48% to 70%) in the heat release rate (HRR) values, a significant delay (up to 47%) in the ignition time in cone calorimetry experiments, and thus an increase (~75%) in the time to flashover. Evolved gas, thermal and fire analysis was used to propose the combined mode of action of DA, Mel and silica in the fire performance improvement of the epoxy system. Tensile and three-point bending flexural tests showed that the addition of DA increases the rigidity of the resin, resulting in a strong increase in the Young's modulus (up to 34%) and in a slight reduction in fracture strength, elongation break and toughness which is typical for non-reactive additives.
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•Self-extinguishing epoxy-silica nanocomposite at very low phosphorus loadings.•In-situ sol-gel silica in the epoxy system prevented melt dripping.•Intumescent system achieved significant reduction in heat release rate (~70%) and delay of the ignition time (~50%).
Functionalized titania are used as fillers to modify the sulfonated poly(ether ether ketone) (SPEEK) membrane for improved proton conductivity and methanol barrier property. The functionalized ...titania sol which contains proton conductive carboxylic acid groups or amino acid groups are derived from a facile chelation method using different functional additives. Then the novel SPEEK/carboxylic acid-functionalized titania (SPEEK/TC) and SPEEK/amino acid-functionalized titania (SPEEK/TNC) hybrid membranes are fabricated via in situ sol–gel method. The anti-swelling property and thermal stability of hybrid membranes are enhanced owing to the formation of electrostatic force between SPEEK and titania nanoparticles. The hybrid membranes exhibit higher proton conductivity than plain SPEEK membrane because more proton transfer sites are provided by the functionalized titania nanoparticles. Particularly, the proton conductivity of SPEEK/TNC membrane with 15% filler content reaches up to 6.24 × 10−2 S cm−1, which is 3.5 times higher than that of the pure SPEEK membrane. For methanol permeability, the SPEEK/TNC membranes possess the lowest values because the acid-base interaction between sulfonic acid groups in SPEEK and amino groups in functionalized titania leads to a more compact membrane structure.
•Carboxylic acid or amino acid functionalized titania sol are prepared.•Functionalized titania is incorporated into SPEEK through in situ sol–gel method.•The proton conductivity of hybrid membrane is 3.5 times higher than pure SPEEK.•The methanol permeability of hybrid membranes is effectively suppressed.
Interfacial polymerization (IP) has been deemed as the principal strategy to fabricate thin film composite (TFC) nanofiltration (NF) membranes. However, the separation performances of TFC membrane ...are prone to be impaired with the issue of trade-off relationship between selectivity and permeability. Herein, a combined IP and in-situ sol-gel method was proposed to synthesis novel thin film nanocomposite (TFN) NF membrane. The nano-enhanced polyamide (PA) functional layer was created by the IP reaction, while the in-situ generated silicon dioxide (SiO2) nanoparticles were formed through the hydrolysis and condensation process. The optimal separation performance was obtained by tailoring the formation process of SiO2 nanoparticles via varying the NaOH concentration. The results revealed that the in-situ generated SiO2 nanoparticles were uniformly distributed within the PA layer, which greatly enhanced the hydrophilicity due to the abundant Si-OH groups. The membrane decorated by 1 ml TEOS under 0.3 wt% NaOH condition possessed a pure water permeability up to 70.69 L m−2 h−1 bar−1 and high rejection rates against dyes (99.99 % for Congo red, 99.55 % for Coomassie blue G-250, 99.39 % for Reactive blue 19), while maintaining low salt rejections (4.92 % for NaCl, 7.14 % for Na2SO4). Meanwhile, the membrane presented an excellent long-term operational stability.
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•SiO2 nanoparticles were in-situ generated inside the polyamide membrane.•SiO2 nanoparticles were uniformly distributed on membrane surface.•The achieved membrane exhibited enhanced separation performance.•The fabrication method is simple.
Nanocomposites containing mixed transition metal oxides demonstrate significant promise as materials for supercapacitors, specifically due to their enhanced surface area, synergistic effect of ...multiple metal cations, excellent electrical conductivity, and improved electrochemical properties. In this study, we synthesized a nanocomposite with a nanograss array morphology consisting of SnO2/CoFe2O4/Fe3O4 using an in-situ sol-gel method. For comparison, we synthesized a composite (CoFe2O4/Fe3O4) without SnO2. Through a systematic characterization employing various analytical techniques, we examined the structural, morphological, and textural attributes of the resulting composites. The results reveal that the phase percentages of CoFe2O4, SnO2, and Fe3O4 were 38%, 33%, and 29% in the SnO2/CoFe2O4/Fe3O4 composite. Also, the nanograss array of SnO2/CoFe2O4/Fe3O4 is composed of nano-sized primary particles, while CoFe2O4/Fe3O4 showed spherical-like nanoparticle morphology. The BET surface area of the SnO2/CoFe2O4/Fe3O4 composite was found to be seven times higher than that of CoFe2O4/Fe3O4. We also evaluated the electrochemical performance of the SnO2/CoFe2O4/Fe3O4 composite as a cathode material for battery-type supercapacitors. The synergistic combination of SnO2 and CoFe2O4/Fe3O4 in the SnO2/CoFe2O4/Fe3O4 electrode resulted in a high specific capacity of 465C g−1 at 1 A g−1, which is 2.5 times higher than the CoFe2O4/Fe3O4 electrode. Additionally, the SnO2/CoFe2O4/Fe3O4 electrode exhibited a remarkable rate capability of 87% at 10 A g−1 and excellent cyclic performance with 96% capacity retention after 5000 cycles. A hybrid supercapacitor was fabricated, featuring a cathode composed of a composite electrode consisting of SnO2/CoFe2O4/Fe3O4 and an anode comprising activated carbon (AC). This fabricated SnO2/CoFe2O4/Fe3O4//AC HSC device configuration exhibited impressive performance characteristics, boasting a notable energy density of 38.4 Wh kg−1 at 1468.2 W kg−1. These findings underscore the significant impact of SnO2 on the physio/electrochemical properties of the CoFe2O4/Fe3O4 composite. The outstanding electrochemical performance of this electrode underscores its potential for application in next-generation hybrid supercapacitors.
•TiO2-MWCNTs nanocomposite was synthesized by using simple in situ sol-gel method at room temperature.•TiO2-MWCNTs nanocomposite shows red shift.•Photodegradation of methyl orange under UV light and ...sunlight carried out successfully also.•TiO2-MWCNTs nanocomposite show photo inactivation of bacteria under visible light.•Synthesized nanocomposite is useful for various applications.
Visible light photoactive titania-multiwalled carbon nanotubes (TiO2-MWCNTs) nanocomposites were synthesized by in situ sol-gel method, in this TiO2 nanoparticles were decorated on the surface of MWCNTs. The XRD analysis shows good crystalline nature of synthesized nanocomposite. UV–vis DRS study confirms the red shift of nanocmposites with respect to the increasing content of MWCNTs. The photocatalytic activity has investigated by degradation of methyl orange dye under ultraviolet as well as sunlight irradiation and photo-inactivation of Bacillus subtilis under visible light irradiation. The MWCNTs exist in the nanocomposite was able to absorb a high amount of photon energy in the sunlight, driving effectively photochemical degradation reactions. In the photodegradation of methyl orange dye under sunlight as well as photo-inactivation of Bacillus substilis under visible light, significant enhancement in the degradation/inactivation reaction rate was observed with the TiO2-MWCNTs (0.5wt.%), nanocomposite as compared to TiO2 NPs. The COD study confirms the environmentally benign nature of photodegraded dye solution. This work provides new insight for the fabrication of sunlight/visible active TiO2-MWCNTs nanocomposite photocatalyst for degradation of organic compounds and photo-inactivation of bacteria.
Fabrication of novel composite proton exchange membranes (PEMs) with efficient proton transfer sites and homogeneous structure is crucial to PEM fuel cells but remains challenging. In this study, ...organic polydopamine sol is synthesized by a facile self-polymerization method and functionalized by abundant −PO3H2 groups, then the composite membrane is fabricated by mixing the functionalized polydopamine sol with Nafion followed by polycondensation of sol. The electrostatic interactions between functionalized polydopamine (FDPA) networks and Nafion matrix confer the composite membrane with excellent interfacial compatibility and enhanced physical, chemical stabilities. Due to the introduction of −PO3H2 groups, the hydrogen-bonded water bridges can be easily constructed and the energy penalty for proton transfer is greatly reduced. Meanwhile, the tradeoff effect between proton conductivity and fuel permeability is surmounted. The composite membrane displays the highest proton conductivity of 0.0314 S cm−1 (80 °C, 40% RH) and selectivity of 7.94 × 104 S s cm−3 (25 °C), which is 15.2 times and 4.5 times higher than those of the recast Nafion, respectively. Compared with recast Nafion, a 58.4% increase in maximum power density is achieved for the Nafion/FDPA-10 composite membrane.
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•Polydopamine sol is prepared facilely and functionalized by −PO3H2 groups.•Organic polydopamine is introduced into Nafion through in situ sol-gel method.•The composite membrane records a 15.2-fold proton conductivity enhancement.•The tradeoff between proton conductivity and fuel permeability is surmounted.
Poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)-silica mixed matrix membranes (MMMs) were synthesized through the in-situ sol–gel method. The effects of the acid–base catalysis conditions and silica ...loading weight on the gas separation performance of the membranes were investigated. The functional groups, crystalline structure, thermal stability, and morphology of the MMMs were examined using Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA), respectively. The results indicate that using the in-situ sol–gel method to synthesize PPO-silica MMMs is beneficial for improving the adhesion between the silica and polymer and for the dispersion of the silica. The additives significantly enhanced the thermal stability of the membranes. Compared with pure PPO membranes, the PPO-silica MMMs prepared with 10 wt.% acid-silica loading exhibited the best H2/CO2 separation properties: H2 permeability was enhanced from 82.1 to 548.7 Barrer, and an H2/CO2 separation ratio of approximately 3.56 was observed.
•Non-defect PPO-silica MMMs were successfully prepared by the in-situ method.•Silica exhibited a good interaction with PPO.•Acid-catalyzed silica significantly improved the gas separation performance of MMMs.•The obtained membranes demonstrated high H2 permeability and H2/CO2 selectivity.
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•A novel approach to prepare organic-inorganic composite PES membrane was proposed.•The modifier P(PEG-PDMS-KH570)@SiO2 was obtained via in-situ sol-gel process.•SiO2 nanoparticles, ...PEG and PDMS segments were enriched on membrane surfaces.•A multi-defense antifouling performance was achieved for composite PES membrane.•The PES/T@SiO2∼4% membrane exhibited superior and sustainable antifouling ability.
In this work, an original amphiphilic copolymer P(PEG-PDMS-KH570) combined with SiO2 nanoparticles (SiO2 NPs) was utilized to prepare polyether sulfone (PES) nanocomposite ultrafiltration (UF) membrane with enhanced antifouling performance. The enrichment of the organic-inorganic modifier P(PEG-PDMS-KH570)@SiO2 were realized at the same time as the formation of PES UF membrane via sol-gel non-solvent induced phase separation (NIPS) process. The interaction between the copolymer P(PEG-PDMS-KH570) and SiO2 NPs furnished a stable and effective antifouling PES UF membrane. Surface morphology, chemical composition characterization and wetting property measurements confirmed the segregation and distribution of the nanocomposite modifier. The multi-defense mechanism from fouling resistance to fouling release of the nanocomposite membranes was investigated by setting bovine serum albumin (BSA) aqueous solution as a model foulant. The antifouling properties of the modified membranes, especially for the PES/T@SiO2∼4% membrane, were effectively improved. The flux decline rate of PES/T@SiO2∼4% membrane was as low as 15.6%, and the flux recover ratio was up to 99.0%. Moreover, the modified membranes also possessed remarkable antifouling stability. Results of this work provide a facile method to construct a hierarchical and heterogeneous membrane surface that could achieve the multi-defense mechanism in efficient water treatment.
•Titania sol functionalized by abundant zwitterions is facilely synthesized.•Nano-sized TiO2 is introduced into separation layer by in situ sol-gel method.•The water flux and salt rejection are ...increased simultaneously.•The antifouling performance of composite membranes is effectively enhanced.
The construction of a compact separation layer with selective channel and hydrophilic surface is a promising way to fabricate the composite nanofiltration membranes with both high selectivity and antifouling performance. In this study, a strategy that incorporating zwitterion functionalized titania (ZTi) into membrane surface through facile in-situ sol-gel process is proposed. The titania sol is firstly prepared using tetrabutyl titanate as the precursor and then functionalized by abundant zwitterions based on the chelation reaction. Finally, the ZTi is introduced into polyamide (PA) on the surface of porous polyethersulfone (PES) by in-situ sol-gel method during interfacial polymerization. The physical and chemical structure of the membrane surface is tuned by varying the loading level of titania. Due to the good interfacial compatibility between inorganic ZTi and PA polymer, the optimized PA-ZTi/PES membrane shows a high water flux of 283.5 L m−2 h−1 MPa−1 and a high Na2SO4 rejection ratio of 92.7%, which overcomes the trade-off effect between permeability and selectivity. Moreover, the PA-ZTi/PES series membranes also show superior antifouling performance with flux recovery ratios of 92.9% (against bovine serum albumin) and 95.6% (against humic acid).
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