Surface Modified TiO2 Nanoparticles Research Articles

Study on preparation, structure, and cooling properties of TiO2/acrylonitrile–styrene–acrylate terpolymer solar reflective nanocomposite

AbstractPreparation, characterization, and cooling properties of TiO2 /acrylonitrile–styrene‐acrylate (ASA) terpolymer solar reflective nanocomposites with various contents of titanium dioxide (TiO2) nanoparticles were investigated. The formation of nanocomposites was monitored by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and contact angle measurements. The cooling features were characterized via ultraviolet–visible–near infrared (UV–vis–NIR) spectrophotometry and heat build‐up tests. FTIR spectra show the disappearance of the vinylic absorption peak at 1636 cm−1 of the modified TiO2 which signifies good chemical interaction between the poly (butyl acrylate) chains and the nanoparticles. DLS measurements revealed relative enlargement in the diameter of nanocomposite latex particles from 107 to 184 nm as the percentage of mineral nanoparticles increased. SEM and TEM analysis revealed the formation of a core‐shell morphology with an almost uniform distribution of nanoparticles in the polymer chains. Spectral properties details obtained using UV–vis–NIR spectrophotometry revealed that surface modification of TiO2 nanoparticles resulted in a more than 7% increase in solar transmittance compared to the raw form. Nevertheless, grafting a thermoplastic shell onto the acrylic core reduced the average solar transmittance from 81.92% to 55.32%. Incorporating TiO2 nanoparticles (up to 6 wt%) into the polymer matrix led to an 18.44% further decrease in solar transmittance compared to the neat ASA. Heat build‐up tests showed enhanced cooling of 10.2, 12.7°C, 13.4°C, and 14.2°C for 0, 2, 4, and 6 wt% of used nanoparticles, respectively.Highlights In situ nanocomposites were synthesized through mini‐emulsion polymerization. Chemical bonding formed between functionalized TiO2 and polymeric matrix. ASA/TiO2 nanocomposite shields >56% of NIR light and 63% of solar light. Nanocomposites reduced heat build‐up temperature by more than 14°C during indoor test.

Self-powered, transparent, flexible, and solar-blind deep-UV detector based on surface-modified TiO2 nanoparticles

Titanium oxide (TiO2) has been widely used as a low-cost, chemically stable, and biologically inert semiconductor for many applications. However, there are a limited number of studies on the application of TiO2 for deep-UV photodetection, which has potential environmental and military applications. In this study, we introduce a facile sol–gel method followed by post-modification with acetic acid (HAc) to prepare wide-bandgap anatase TiO2 (3.83 eV) for use as a solar-blind deep-UV photoabsorber. The beneficial effects of simple post-modification on the structural, optical, and electrical properties of TiO2 were comprehensively investigated. When TiO2 nanoparticles are functionalized by an appropriate number of HAc, O vacancies in TiO2 are significantly reduced while the bandgap is increased with reduced particle size. As a result, the HAc-modified TiO2-based deep-UV photodetector exhibits high specific detectivity, fast response time, and R254:R365 rejection at zero bias. Furthermore, the device displays good stability with a nearly constant photoresponse even after one month of storage and under stringent bending strain. The average visible transmittance of the device reaches as high as 80%. The results suggest that the device can be used as an efficient TiO2-based solution-processable solar-blind deep-UV photodetector, with self-powered operability, wearability, and transparency.

Effect of TiO2 nanoparticles on the tribological properties of lubricating oil: an experimental investigation

Nano-lubricants offer improved tribological properties in many applications, such as machines and engines. The presence of nanoparticles in the lubricating oil affects its wear, friction, thermal, chemical and physical properties in many ways. Titanium dioxide (TiO2) is a promising lubricant additive for enhanced engine efficiency. This article reports the effect of 10 W-30 pure base engine oil suspended TiO2 nanoparticles. Four different volume concentrations (0.01%, 0.025%, 0.050% and 0.075%) of TiO2 nanoparticles in the base lubricating oil are used for the analysis. The tribological tests were performed at ambient temperature as well as at 75 °C using a four ball tribometer. Scanning electron microscope (SEM) and Alicona Inginite Focus G5 microscope were used to analyze the worn surface. The results show that the surface-modified TiO2 nanoparticles can remarkably improve the load-carrying capacity, the friction reducing, and anti-wear abilities of the additive oil. The diameter of the wear trace and the coefficient of friction are the tribological properties analyzed for the nano-lubricant prepared at different volume concentration (VC). It was found that the diameter of the wear scar and the coefficient of friction increase with increasing VC of TiO2 nanoparticles in the lubricating oil. The main objective of the paper is to present the recent progress and, consequently, to develop a comprehensive understanding of the tribological behavior of engine oil mixed with TiO2 nanoparticles.

Improving the stability of nanofluids via surface-modified titanium dioxide nanoparticles for wettability alteration of oil-wet carbonate reservoirs

The main challenge of the application of nanofluids for enhanced oil recovery (EOR) in oil-wet carbonate reservoirs is maintaining their stability under high-temperature and high-salinity which is normally seen in reservoir conditions. In this work, surface-modified TiO2 nanoparticles were synthesized by N-(2-Aminoethyl)−3-Aminopropyltrimethoxysilane (AEAPTMS) as a coupling agent for surface modification of nanoparticles. Zeta potential and dynamic light scattering analyses were used to evaluate the stability of the prepared nanofluids. Results indicated that nanofluids had high stability in 90 °C and 20 wt% salinity. The influence of nanofluids on wettability alteration of carbonate rocks was studied by measuring the contact angle value. Untreated rock samples were strongly oil-wet, with water advancing and receding contact angles of 165.1° and 166.2°, respectively. After treatment with 3wt% concentration of surface-modified TiO2 nanoparticles, the rock plate wettability changed to a water-wet state, with water advancing and receding contact angles of 37.6° and 48.2°, respectively. Suggested surface-modified TiO2 nanoparticles were more effective in wettability alteration of the rock surfaces compared to the un-modified TiO2 nanoparticles. Furthermore, higher concentration of nanoparticles, higher the ability of the nanoparticles on changing the rock wettability.

Antibacterial nanocomposite films based on Poly(vinyl alcohol)/TiO2-Folic acid: Study of physicochemical, optical, and thermal characteristics

In different industries, the manufacturing of antibacterial packaging is an important challenge for researchers. The goal of this project is the fabrication of antibacterial nanocomposite (NC) films based on poly(vinyl alcohol) (PVA) and titanium dioxide-folic acid (TiO2-FA) nanoparticles (NPs). Surface modification of TiO2 NPs was done with FA (as biosafe material) molecule and ultrasonic method. Various methods characterized the structure of the prepared PVA/TiO2-FA NC films. The thermogravimetric analysis displayed that the prepared PVA/TiO2-FA NC films had higher thermal stability than the neat PVA. Morphology study of the NC films showed that the TiO2-FA NPs with spherical shape had an excellent dispersion in the PVA matrices. PVA/TiO2-FA NC films had high absorption in Ultra-violet (UV)-A and UV-B regions. Also, the prepared NC film showed the lower permeability for oxygen gas compared with neat PVA. Furthermore, it was found that under UV radiation, the PVA/TiO2-FA NC films showed better antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria.

Hydrophilic and hydrophobic films based on polyurethane cationomers containing TiO2 nanofiller

Polyurethane cationomers thin films containing (0–2 wt%) surface functionalized TiO2 as ecological water dispersions were obtained, and the structure of the cationomers have been confirmed using FTIR and NMR methods. Incorporation of the surface modified TiO2 nanoparticles caused considerable changes in the thermal, mechanical, and surface properties of the PU films. Importantly, films made with MDI isocyanate surface-modified TiO2 were hydrophobic and their free surface energy (FSE) was below 35 mJ/m2, while films containing unmodified TiO2 were hydrophilic with FSE above 48 mJ/m2. SEM observations exhibited uniform dispersion of nanoparticles in PU matrix. The activation energy of the glass transition process was calculated based on multifrequency TOPEM DSC data and the higher activation energy was found for composites with higher content of PU/TiO2 or PU/f-TiO2 due to the stronger hydrogen bonding between soft segment microdomains and hard segments after incorporation of PU/TiO2 or PU/f-TiO2. Good thermal and mechanical properties, which correspond to those of PU elastomers, are promising features for the application of the obtained cationomers as modern coating materials.

Interactions between TiO2 nanoparticles and plant proteins: Role of hydrogen bonding

Titanium dioxide (TiO2) particles are widely employed in foods and supplements as lightening agents. A substantial fraction of the particles in commercial TiO2 ingredients fall within the nanoscale, i.e., they have diameters below 100 nm. A biocorona can form around TiO2 particles when they are incorporated into food matrices containing plant proteins. In this study, we investigated the molecular interactions between two hydrophobic plant proteins (gliadin and zein) and four types of surface-modified TiO2 nanoparticles (TCN, TCN-1, TCN-2 and TCN-3). Ultraviolet–visible absorption, fluorescence quenching, and Fourier transform infrared spectroscopy indicated that the plant proteins interacted with the surfaces of the TiO2 nanoparticles, resulting in changes in their molecular conformations. Quartz crystal microbalance analysis indicated that the mass of the hard corona increased as the number of hydroxyl groups on the surfaces of the TiO2 nanoparticles increased, which implied that hydrogen bonding played an important role in the formation of the biocorona. These results provide a better understanding of the interactions that may occur in food matrices containing both plant proteins and TiO2 nanoparticles.

Printable dielectric elastomers of high electromechanical properties based on SEBS ink incorporated with polyphenols modified dielectric particles

In this work, a recently developed 3D additive processing technology termed electrohydrodynamic (EHD) printing was employed to fabricate dielectric elastomer (DE) films by using styrene-ethylene-butylene-styrene (SEBS) inks with the addition of high dielectric titanium dioxide (TiO2) nanoparticles. In order to improve the dispersibility of TiO2 in the SEBS matrix, extracted walnut polyphenols were utilized for surface modification of TiO2 nanoparticles labelled wp-TiO2. The effect of the applied voltage on the ink jet morphology of the obtained SEBS based inks during EHD printing was analyzed. The prepared films had precision patterned shapes and their morphology was studied. It revealed that the dispersibility of TiO2 nanoparticles in the SEBS matrix and their compatibility were greatly improved using this procedure. Furthermore, the printed DE films were found to have excellent mechanical, dielectric and electromechanical properties. For the range of DEs fabricated, the SEBS/10%wp-TiO2 composite exhibited the maximum actuated area strain of 21.5% at an electric field of about 34.0 V/μm without degradation of other properties.

Surface modification of TiO2 nanoparticles with CuO for visible-light antibacterial applications and photocatalytic degradation of antibiotics

This paper investigates the synthesis and characterization of photoactive TiO2/CuO nanocomposites for the simultaneous antibacterial applications and photocatalytic removal of Amoxicilline from wastewaters. Effective removal of biological and organic contaminants from water resources has become a global challenge due to contaminants' complexity and extensive use. TiO2/CuO heterojunctions with different CuO loadings were synthesized using a straightforward precipitation method. Electron microscopy, energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), ultraviolet–visible (UV-VIS) analyses were used to characterize synthesized samples. Antibacterial activities of samples were investigated against Staphylococcus aureus. Also, the applicability of synthesized powders in the photocatalytic removal of Amoxicilline from wastewater was methodically investigated. Results showed that the photocatalytic activity of synthesized TiO2/CuO nanocomposites is highly dependent on the CuO loadings of samples. CuO loading can also increase the light absorption within the visible light region, making TiO2/CuO samples applicable in the visible light region. Results also showed that CuO loading greatly enhances the antibacterial characteristics of samples.

Surface modification of TiO2 nanoparticles with 1,1,1-Tris(hydroxymethyl)propane and its coating application effects on castor seed oil-PECH blend based urethane systems

Surface modification of peripheral hydroxyl groups of TiO2 with trimethylolpropane (TMP) was successfully carried out and characterized. This hybrid material (TiO2-TMP) was added in percentages to a polyol blend of castor seed oil (a renewable resource and nontoxic material) and poly(epichlorohydrin)-triol (PECH-triol) {a cross-linker}. After ultrasonication of the polyol blend with TiO2-TMP, through a one-pot synthesis, the mixture was made to react with polymeric 4,4′-methylene diphenyl diisocyanate (PMDI) using 4-Methyl-2-pentanone as a reacting solvent. The synthesized PECH-triol and composite coating films structural elucidation was carried out using FTIR, 1H NMR and 13C NMR. The pristine/undoped and composite films were subjected to specific coating evaluations such as morphology (FESEM), XRD, thermal stability, mechanical property (UTM), chemical resistance, antimicrobial activity and corrosion resistance (Tafel plot). The doped composites showed improved coating properties, especially PU-TiO2-TMP (1.0 wt%), which possesses the highest percentage of TiO2-TMP nanoparticle.

Experimental investigation of base oil properties containing modified TiO2/CuO nanoparticles additives

The majority of lubricating oil properties are the product of a material being used to enhance or produce the desired properties. Different materials with various nanostructures are now being used as new additives to improve lubricants’ properties due to their peculiar characteristics. In this study, oleic acid was used to surface-modified TiO2 and CuO nanoparticles to enhance the dispersion and stability of Nanofluid. The X-ray diffraction and Fourier transform Infrared spectroscopy FT-IR used to characterize the nanoparticles. The main objective of this paper was to investigate the influence of adding TiO2 -CuO nanoparticles on the thermal-physical properties such as kinematic viscosity, viscosity index, pour point and flash point of base oil and nano-lubricating oil, which is prepared by different concentration (0, 0.2, 0.5, 0.8, and 1 %) by weight, and also the contact pressure (load – carrying capacity) was examined by using commercial portable Timken tester. The results showed increases in viscosity index and flash point of nano-lubricant oil by 7.69% and 7.07%, respectively.

Controlled growth of ultrasmall Cu2O clusters on TiO2 nanoparticles by atmospheric-pressure atomic layer deposition for enhanced photocatalytic activity

This work presents a gas-phase approach for the synthesis of Cu2O/TiO2 powder-based photocatalysts using atomic layer deposition (ALD). The process is carried out in a fluidized bed reactor working at atmospheric pressure using (trimethylvinylsilyl)-hexafluoroacetulacetonate copper(I) as the Cu-precursor and H2O vapor as the oxidizer. The saturating regime of the chemical reactions and the linear growth of ALD are achieved. In combination with the unsaturated regime, the ALD approach enables the deposition of ultrasmall Cu2O clusters with average diameters in the range of 1.3–2.0 nm, narrow particle size distributions and tunable Cu2O loadings on P25 TiO2 nanoparticles. The photocatalytic performance of Cu2O/TiO2 photocatalysts is investigated by the degradation of organic dyes, including Rhodamine B (RhB), methyl orange, and methylene blue; the results demonstrate that the surface modification of TiO2 nanoparticles by Cu2O nanoclusters significantly enhances the photocatalytic activity of TiO2. This is attributed to the efficient charge transfer between Cu2O and TiO2 that reduces the charge recombination. The photocatalytic reaction mechanism is further investigated for the degradation of RhB, revealing the dominating role of holes, which contribute to both direct hole oxidation and indirect oxidation (i.e. via the formation of hydroxyl radicals). Our approach provides a fast, scalable and efficient process to deposit ultrasmall Cu2O clusters in a controllable fashion for surface engineering and modification.

Surface modification of TiO2 nanoparticles with terephthalic acid in supercritical carbon dioxide

This paper presents a supercritical CO2 strategy for surface modification of TiO2 nanoparticles with carboxylic acids. The reaction between TiO2 nanoparticles and terephthalic acid molecules in sc-CO2 provides carboxylic acid-modified TiO2 nanoparticles with a modification efficiency much higher than the conventional solvent immersion method. From the statistical method of response surface methodology, modifier ratio 4.04 (mol/mol), temperature 401.5 K, and pressure 14.8 MPa resulted in an optimum modification rate of 25.34%. The modified TiO2 was characterized by FTIR, TG-DTA, FE-SEM, TEM-EDS, and zeta potential analysis. The results showed the surface modification of TiO2 in sc-CO2 is made of modifier molecules bonding chemically. Surface modification by terephthalic acid affects the surface electrical property of TiO2 nanoparticles in water, leading to a positive charge surface. Since this method is ecologically and environmentally friendly, it can be applied in precursor composites for the synthesis materials of biomedical application.

Surface Modification of TiO2 nanoparticles using Conducting Polymer Coating: Spectroscopic, Structural, Morphological Characterization and Interaction with Dye Molecules

In the present research, the surface of titanium dioxide nanoparticles was modified using a conducting polymer coating in the presence of an oxidizing agent. The structure and morphology of as-modified polypyrrole-coated titanium dioxide nanoparticles were investigated by X-ray diffraction and Transmission electron microscopy techniques. The nitrogen adsorption-desorption performance of as-modified polypyrrole-coated titanium dioxide nanoparticles were also investigated to revealed its details of specific surface area, structural properties and pore geometries. The polypyrrole coated titanium dioxide nanoparticles were utilized for adsorption of hazardous anionic dye (Congo red) from aqueous solution. The adsorption of Congo red dye onto polypyrrole-coated titanium dioxide nano-adsorbent was confirmed by advanced instrumental techniques such as Fourier transform infrared spectroscopy, Field emission scanning electron microscopy, Energy dispersive x-ray spectroscopy and Elemental mapping analysis. The adsorption performance of polypyrrole-coated titanium dioxide nano-adsorbent was evaluated by batch experimental technique. The effects of different parameters such as pH, contact time, and dose on the adsorption tests were also determined. The highest adsorption of Congo red dye (98.75%) was achieved at pH ˜3 using 50 mg of polypyrrole-coated titanium dioxide nano-adsorbent. The reusability of polypyrrole-coated titanium dioxide nano-adsorbent was also evaluated by several adsorptions-desorption cycles. The reusability result demonstrated excellent adsorption potential of polypyrrole-coated titanium dioxide nano-adsorbent for water-treatment application.

Heteroacoagulation of lignocellulose fibers-based biotemplates and functionalized TiO2 nanoparticles to tailor film microstructures

The heterocoagulation of lignocellulose nanofibers (LCNFs) with functionalized TiO2 nanoparticles (NPs) is presented as an innovative revalorization strategy for the exploitation of lignocellulose wastes. Their use as bio-templates could be considered a promising alternative in a current biorefinery scheme, since the massive production of porous materials in numerous nanotechnological applications, could offer new alternatives of exploitation. The surface modification of TiO2 NPs by adsorption of polyetilenimine (PEI) favors its anchorage with LCNFs through a peptide bond during heterocoagulation in aqueous suspension. The functionalization of LCNFs with TiO2 NPs results in organic–inorganic core–shell nanostructures, used to shape coatings by dipping, and sinter them at low temperature (450 °C). In this process, the LCNFs were used as endo-templates for shaping stable porous coatings, when they burn during the consolidation of the inorganic structure. In this work, the successful inclusion and homogeneous distribution of biomaterials (LCNF templates) in the semiconductor inorganic microstructure is discussed in terms of dye loading (by UV–Visible Spectroscopy), photovoltaic efficiency and charge transfer (by Electrochemical Impedance Spectroscopy, EIS) in a Dye Sensitized Solar Cell (DSSC). Results confirm that the TiO2/template network yielded better photoefficiency and electron transport properties than mesoporous films assembled only from TiO2 NPs. The preparation of TiO2-based photoanodes with enhanced performance (with an efficiency value around 6%, for a thickness of 8.7 µm) allows validating the successful colloidal procedure herein employed.

Synthesis of methanol blocking PVA-TiO2 cation exchange membrane for direct methanol alkaline fuel cell

Polyvinyl alcohol (PVA) based cation exchange membrane has been synthesized for direct methanol alkaline fuel (DMAFC) cells by phase inversion technique coupled with chemical reaction. Nanocomposite membranes have been prepared by adding different amounts of titanium dioxide (TiO2) nanoparticles into the sulfonated PVA solution. PVA was sulfonated by sulfosuccinic acid solution. Sodium ion conducting membranes are formed by a typical chemical reaction induced phase inversion process, using a nonsolvent bath of sodium hydroxide (NaOH) and sodium sulfate (Na2SO4). The phase inversion technique coupled with chemical reaction significantly modified the chemical structure; improved thermal, mechanical, and surface properties of the sulfonated PVA based nanocomposite membrane. The mechanical and thermal properties of the membrane were investigated by UTM and TGA respectively. The chemical structure of membranes was analyzed by FTIR spectrometer. The presence of the TiO2 nanoparticles and sodium ions in the composite membrane was analyzed with the EDX technique. The surface morphology of membranes was studied by SEM micrographs. Moreover, water uptake, sodium ion conductivity, and methanol permeability of the membrane were altered with varying amounts of TiO2. Surface modified TiO2 nanoparticles enhanced the ionic conductivity of the composite membrane to the range of 10-−2 S/cm. Furthermore, the value of the methanol permeability was obtained in the order of 10-7 cm2/s.

Investigating Catechol Surface Modification of TiO2 for the Development of High Performance Photoelectrochemical Biosensors

DNA biosensors are chemical sensors which are used to detect concentrations of specific DNA sequences or register DNA related biological events. There is significant interest in research into the design and optimization of DNA biosensors as they allow for rapid detection of cancers and infectious diseases 1,2. Photoelectrochemical (PEC) techniques can be applied to achieve high performance DNA biosensors with low cost and ultra-sensitivity. In this work, we explored the surface modification of TiO2 nanoparticles (NP) with various catechol molecules and used them to fabricate photoelectrodes for signal-off PEC DNA biosensors. Catechol modification provided dual functionality to the TiO2 NP photoelectrodes: it enhanced their PEC response and provided a molecular linker for attaching probes that capture target DNA.The surface modification of TiO2 NPs was done by adding aqueous solutions of catechol molecules to a suspension of TiO2. Adsorption of catechol on TiO2 took place very rapidly, indicated by a quick change in the colour of the suspension. The catechol-modified TiO2 suspensions were dropdeposited on indium tin oxide coated polyethylene terephthalate (ITO/PET) substrates and oven baked to produce photoelectrodes for the PEC DNA biosensor. Seven catechol molecules were used for surface modification: Caffeic acid (CA), 3,4-Dihydroxybenzaldehyde (DHBA), 3,4-Dihydroxybenzoic acid (DHB), 3,4-Dihydroxy-L-phenylalanine (DOPA), 3,4-Dihydroxyphenylacetic acid (DHPL), 2,3,4-Trihydroxybenzaldehyde (THBA), 2,3,4-Trihydroxybenzoic acid (THB). The photoelectrodes were optically characterized via ultraviolet/visible (UV/vis) spectroscopy and incident photon-to-electron conversion efficiency (IPCE). Additionally, the PEC current of the photoelectrodes were measured using chronoamperometry under white light excitation.Compared against unmodified TiO2, the UV/Vis spectroscopy and IPCE displayed increased light absorption in the visible range and red-shifting for the catechol-modified TiO2 photoelectrodes. This correlated to a great improvement in photocurrent generation. CA-modified TiO2 resulted in the largest increase in photocurrent, over 20 times from the unmodified TiO2 and therefore it was used as the basis for our PEC DNA biosensor. Single stranded DNA (ssDNA) probes were deposited onto the photoelectrodes, followed by target ssDNA deposition. The difference in PEC current after probe deposition and target deposition indicated the concentration of target DNA. A calibration curve was plotted with PEC current density as a function of target DNA concentration, which decreased logarithmically and ranged from 100 nM – 100 fM. A limit of detection (LOD) of 2.38 pM was estimated at a signalto-noise ratio of 3Sx/y (where Sx/y is the root-mean-square error (RMSE)).It is evident from our investigation that functionalizing TiO2 with catechol ligands greatly improves its optical properties which lead to a greater PEC current generation. In particular, high PEC current resulting from the combination of CA and TiO2 can form the basis for high-performance signal-off PEC DNA biosensors with a high dynamic range and low LOD. 1. Beltrán, A. P. & García, M., DNA biosensors and biomarkers to cancer detection. International Journal of Biosensors and Bioelectronics, 4(1), 20-21 (2018)2. Chua, A., Yean, C. Y., Ravichandran, M., Lim, B. & Lalitha, P., A Rapid DNA Biosensor for the Molecular Diagnosis of Infectious Disease. Biosensors and Bioelectronics, 26(9), 3825-3831 (2011)

In-situ coating TiO2 surface by plant-inspired tannic acid for fabrication of thin film nanocomposite nanofiltration membranes toward enhanced separation and antibacterial performance

A major issue hindering development of thin film nanocomposite (TFN) nanofiltration (NF) membrane is the interfacial defects induced by nanomaterial aggregation in top layer. Although various nanomaterials surface modification strategies have been developed to eliminate the interfacial defects, they usually involve extra modification steps and complex post-treatments. Inspired by the substrate-independent coating ability of tannic acid (TA) and the fact that the phenolic hydroxyl groups in TA can react with acyl chloride group in trimesoyl chloride, a TA coating solution containing TiO2 nanoparticles was used as an aqueous phase of interfacial polymerization to prepare interfacial modified TFN NF membranes in this study. Surface modification of TiO2 nanoparticles and interfacial polymerization can be carried out in a single step without any extra pre-modification step. It was found that the TA coating on TiO2 nanoparticles surface could decrease TiO2 aggregations and enhance interfacial compatibility between TiO2 and polyester matrix. The TFN NF membrane prepared at a TiO2 loading of 0.020 wt% exhibited a pure water flux of 28.8 L m-2 h−1 (284% higher than that of the controlled TFC membrane), and possessed enhanced NaCl and Na2SO4 rejections of 57.9% and 94.6%, respectively, breaking through the trade-off between permeability and selectivity.

Autonomous Self-Healing of Electrical Degradation in Dielectric Polymers Using In Situ Electroluminescence

Summary Dielectric polymers are ubiquitous as electrical insulation in electrical power systems and electronic devices. Electrical treeing is typically regarded as an irreversible degradation process of dielectric polymers subjected to high electric stresses, which significantly limits their lifespan and endangers the reliability of electronics and electrical power systems. Here, we report self-healing polymers consisting of microcapsules that are capable of completely restoring the dielectric properties as a direct response to electrical tree degradation. We design the microcapsules with a relatively higher dielectric constant than polymer matrix to guide the propagation of electrical trees. The electroluminescence generated in situ during electrical treeing of polymers triggers crosslinking of the healing agents released from the capsules to repair the electrically damaged areas under ambient conditions. Notably, the breakdown strength of the mended region is largely enhanced upon healing, which was initiated at different locations. The integration of autonomous healing capability into dielectric materials opens new avenues to smart polymers for electronics and energy applications.

Surface Modification of Nanocrystalline TiO2 Materials with Sulfonated Porphyrins for Visible Light Antimicrobial Therapy

Highly-active, surface-modified anatase TiO2 nanoparticles were successfully synthesized and characterized. The morphological and optical properties of the obtained (metallo)porphyrin@qTiO2 materials were evaluated using absorption and fluorescence spectroscopy, scanning electron microscopy (SEM) imaging, and dynamic light scattering (DLS). These hybrid nanoparticles efficiently generated reactive oxygen species (ROS) under blue-light irradiation (420 ± 20 nm) and possessed a unimodal size distribution of 20–70 nm in diameter. The antimicrobial performance of the synthetized agents was examined against Gram-negative and Gram-positive bacteria. After a short-term incubation of microorganisms with nanomaterials (at 1 g/L) and irradiation with blue-light at a dose of 10 J/cm2, 2–3 logs of Escherichia coli, and 3–4 logs of Staphylococcus aureus were inactivated. A further decrease in bacteria viability was observed after potentiation photodynamic inactivation (PDI), either by H2O2 or KI, resulting in complete microorganism eradication even when using low material concentration (from 0.1 g/L). SEM analysis of bacteria morphology after each mode of PDI suggested different mechanisms of cellular disruption depending on the type of generated oxygen and/or iodide species. These data suggest that TiO2-based materials modified with sulfonated porphyrins are efficient photocatalysts that could be successfully used in biomedical strategies, most notably, photodynamic inactivation of microorganisms.