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Dielectric property of modified barium titanate/polyamide 11 nanocomposites with different surfactants
摘要： Barium titanate/polyamide 11 (BT/PA11) nanocomposites were prepared by modifying BT nanoparticles with dry surface modification process, which had well dispersion, high dielectric constant, and low dielectric loss. Various methods were reported to improve dispersion and compatibility with complex process and high cost. Herein, three surfactants [γ-aminopropyl triethoxy silane (KH550), sorbitan monostearate (SP60), and octadecyl phosphate ester (OPE)] were chosen to modify BT nanoparticles. Then modified-BT nanoparticles were blended with PA11. The structure was characterized by Fourier transform infrared, scanning electron microscope, and wide angle X-ray diffraction. Dielectric property was studied by broadband dielectric spectroscopy. The frequency dependence and temperature dependence of dielectric constant, dielectric loss, and dielectric modulus were analyzed. In general, dielectric property has strong frequency and temperature dependence. Furthermore, dielectric spectra shows that modified BT/PA11 nanocomposites have higher dielectric constant, lower dielectric loss, fewer interface polarization, and more dipole polarization. In contrast to three surfactants, OPE-BT nanoparticles have better effects, whose dielectric constant increases from 19 to 28 at 1 Hz, and dielectric loss decreases from 0.36 to 0.23. Meanwhile, mechanical property was characterized by universal testing machine. In all, the work improves dispersion of BT nanoparticles and dielectric property with easy process and low cost. ? 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47447.
关键词： BT/PA11 nanocomposites,dielectric property,modification,surfactants
更新于2025-09-23 15:23:52
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Blue Electrogenerated Chemiluminescence from Halide Perovskite Nanocrystals
摘要： Electrogenerated chemiluminescence (ECL) has been extensively used in ultrasensitive electroanalysis because it can be generated electrochemically without using expensive optics and light sources. Visible ECL emission can be obtained with a reasonable quantum yield and stability. Blue ECL is rare and often suffers from stability and poor quantum efficiency. Blue ECL emission at 473 nm from organometallic halide perovskite nanocrystals (PNCs), CH3NH3PbCl1.08Br1.92, is reported here for the first time using tripropylamine (TPrA) as co-reactant. The blue ECL emission peak resembles its photoluminescence peak position. In addition to this blue emission peak, the ECL spectra of CH3NH3PbCl1.08Br1.92 PNCs also showed a broad ECL peak at 745 nm. Generation of the second ECL peak at 745 nm from CH3NH3PbCl1.08Br1.92 PNCs was can be explained by the existence of surface trap states on as-synthesized PNC due to incomplete surface passivation. Halide anion tunability of ECL emission from CH3NH3PbX3 (X: Cl, Br, I) PNCs is also demonstrated. The fluorescence microscopy image of single PNC and stability of selected single PNCs are presented in this with simultaneous acquisition of fluorescence spectra using 405-nm laser excitation. The photoluminescence (PL) decay was described by PL lifetime (τ) of 1.2 ns. The effect of the addition of surfactants (oleic acid and n-octylamine) on the fluorescence intensity and stability of CH3NH3PbCl1.08Br1.92 PNCs is also discussed.
关键词： Surfactants,Blue light emission,ECL (electrogenerated chemiluminescence),Photoluminescence (PL),Perovskite nanocrystals (PNCs),Photoluminescence quantum yield (PLQY)
更新于2025-09-23 15:23:52
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Formation of 45° Silicon (110) Surface Using Triton X- <i>n</i> Surfactants in Potassium Hydroxide for Infrared Applications
摘要： Silicon (Si) micromirrors are an integral feature for many micro-optomechanical systems (MOEMS). Such mirrors are generally wet etched in alkaline solution at elevated temperature. For 90? beam steering applications, 45? slanted Si (110) plane is the prime choice fabricated with the incorporation of tensioactive surfactants. Here, Triton-Si and Triton-hydroxide (OH?)/H2O interaction using varying hydrophilic chain length Triton (X-45, X-100 and X-405) were investigated. The surfactant concentration was varied from 0 to 1000 ppm in potassium hydroxide (KOH). Triton molecules were shown to adsorb preferentially on (110) than on (100) surface. Longer chain length Triton hampered OH? access to Si surface resulting in slower etch rate. In contrast, contact angle measurement suggested that shorter Triton interfaced better with Si surface. Later, Si wafers etched in Triton 10 ppm – KOH were examined. The measured output for (110)X-45, (110)X-100, (110)X-405 and polished Si wafer reference (Rq < 5?) mirrors were 0.58, 0.76, 0.72 and 1.25 mW, respectively. Subsequently, Si-SiO2 thin film in [HLHL]2-substrate configuration was fabricated. Broadband micromirror for use in 3.0–5.5 μm spectrum range was experimentally realized with reflected efficiency of 73%.
关键词： wet etching,optical measurement,Silicon micromirrors,Triton X-n,surface roughness,potassium hydroxide,surfactants
更新于2025-09-23 15:23:52
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Photo-isomerization of azobenzene containing surfactants induced by near-infrared light using upconversion nanoparticles (UCNPs) as mediator
摘要： Here we report on photo-isomerization of azobenzene containing surfactants induced during irradiation with near-infrared (NIR) light in the presence of upconversion nanoparticles (UCNPs) acting as mediator. The surfactant molecule consists of charged head group and hydrophobic tail with azobenzene group incorporated in alkyl chain. The azobenzene group can be reversible photo-isomerized between two states: trans- and cis- by irradiation with light of appropriate wavelength. The trans-cis photo-isomerization is induced by UV light, while cis-trans isomerization proceeds either thermally in dark, or can be accelerated by exposing to illumination with longer wavelength typically in blue/green range. We present the application of lanthanide doped upconversion nanoparticles (UCNPs) to successfully switch azobenzene containing surfactants from cis to trans conformation in bulk solution using NIR light. Using Tm3+ or Er3+ as activator ions, the UCNPs provide emission in the spectral range of 450 nm < λem < 480 nm (for Tm3+, three and four photon induced emission) or 525 nm < λem < 545 nm (for Er3+, two photon induced emission), respectively. Especially for UCNPs containing Tm3+ a good overlap of the emission with the absorption bands of the azobenzene is present. Under illumination of the surfactant solution with NIR light (λex= 976 nm) in the presence of the Tm3+-doped UCNPs, the relaxation time of cis-trans photo-isomerization was increased by almost 13-times compared to thermal relaxation. The influence of thermal heating due to the irradiation using NIR light was shown to be minor for solvents not absorbing in NIR spectral range (e.g., CHCl3) in contrast to water, which shows a distinct absorption in the NIR.
关键词： azobenzene containing surfactants,kinetic of cis-trans isomerization,up-conversion particles
更新于2025-09-23 15:23:52
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Facile green synthesis of organosilica nanoparticles by a generic “salt route”
摘要： Colloidal silica has wide applications and the global demand of specialty silica is continually increasing. Therefore, it is significant to develop a synthetic method that is simple, versatile, energy-saving, ecologically benign, and easily scalable. Biomimetic synthesis of colloidal silica represents a promising strategy; however, it often requires the synthesis or extraction of specialized macromolecules. In this paper, we present a novel aqueous, one-pot, and green route for synthesis of organosilica nanoparticles. The reaction systems contain only water, an organosilane precursor, a salt, and a commonly used surfactant or amphiphilic polymer. The reaction was performed at ambient conditions without adding any additional solvent, energy, and harsh chemicals. The key findings include the novel identification of 5 salts (i.e. nitrite, fluoride, dibasic phosphate, acetate, and sulfite) that can catalyze organosilica condensation and the resulting formation of nano-colloids. Moreover, the presence of amphiphilic molecules is essential for salt catalysis at low salt concentrations and at nearly neutral pH. Solid-state NMR and in-situ ATR-FTIR studies confirmed that organosilica condensation is highly efficient under the mild reaction condition. In conclusion, the present study demonstrates that "soft" interaction between salts and surfactants (or polymers) can be utilized to construct an effective platform for synthesis of "hard" organosilica particles. The proposed method is generic and applicable to a wide range of commonly used surfactants (viz. non-ionic, anionic, cationic) and amphiphilic polymers, as well as to organosilanes with various hydrophobic functional groups (e.g. mercaptopropyl, vinyl, and methyl).
关键词： Salts,Microreactors,Surfactants,Organosilica nanoparticles,Biomimetic synthesis,Colloids
更新于2025-09-23 15:22:29
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Quantifying Double-Layer Potentials at Liquid–Gas Interfaces from Vibrational Sum-Frequency Generation
摘要： Vibrational sum-frequency generation (SFG) spectroscopy is demonstrated as a fast method to quantify variations of the electric double-layer potential ?0 at liquid?gas interfaces. For this, mixed solutions of nonionic tetraethyleneglycol-monodecylether (C10E4) and cationic hexadecyltrimethylammonium bromide (C16TAB) surfactants were investigated using SFG spectroscopy and a thin-film pressure balance (TFPB). Derjaguin?Landau?Verwey?Overbeek analysis of disjoining pressure isotherms obtained with the TFPB technique provides complementary information on ?0, which we apply to validate the results from SFG spectroscopy. By using a single ?0 value, we can disentangle χ(2) and χ(3) contributions to the O?H stretching modes of interfacial water molecules in the SFG spectra. Having established the latter, we show that unknown double-layer potentials at the liquid?gas interface from solutions with different C16TAB/C10E4 mixing ratios can be obtained from an analysis of SFG spectra and are in excellent agreement with the complementary results from the TFPB technique.
关键词： disjoining pressure,Vibrational sum-frequency generation,electric double-layer potential,thin-film pressure balance,liquid?gas interfaces,surfactants
更新于2025-09-23 15:22:29
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Raman spectroscopy combined with advanced chemometric methods: A new approach for detergent deformulation
摘要： Deformulation of a commercial surfactant mixture using RAMAN spectroscopy and advanced chemometric tools have been investigated. Since the use of surfactants is drastically expanding, their fine identification and quantification are required for quality control and regulation. Dilution of the detergent mixtures combined with RAMAN spectroscopy for signal extraction tools allowed the extraction of the first information concerning the composition of the mixture. The raw materials identified were thus used in an experimental design to obtain a robust model for the determination of detergent composition. The combination of chemometric tools (Independent Component Analysis and Partial Least Square) and spectroscopic methods provided pertinent information for detergent composition. This methodology can easily be transposed to the industrial world.
关键词： detergents deformulation,RAMAN spectroscopy,surfactants characterization,design of experiments,Chemometrics,blind source separation methods
更新于2025-09-23 15:21:21
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Oligonucleotide Detection and Optical Measurement with Graphene Oxide in the Presence of Bovine Serum Albumin Enabled by Use of Surfactants and Salts
摘要： As graphene oxide-based oligonucleotide biosensors improve, there is a growing need to explore their ability to retain high sensitivity for low target concentrations in the context of biological fluids. Therefore, we innovatively combined assay milieu factors that could influence the key performance parameters of DNA hybridization and graphene oxide (GO) colloid dispersion, verifying their suitability to enhance oligonucleotide–GO interactions and biosensor performance. As a model system, we tested single-strand (ss) DNA detection in a complex solution containing bovine serum albumin (BSA) and salts with surfactants. A fluorescein conjugated 30-mer oligonucleotide ssDNA probe was combined with its complementary cDNA target, together with solute dispersed GO and either non-ionic (Triton X-100 and Tween-20) or anionic sodium dodecyl sulfate (SDS) surfactants. In this context, we compared the effect of divalent Mg2+ or monovalent Na+ salts on GO binding for the quench-based detection of specific target–probe DNA hybridization. GO biosensor strategies for quench-based DNA detection include a “turn on” enhancement of fluorescence upon target–probe interaction versus a “turn off” decreased fluorescence for the GO-bound probe. We found that the sensitive and specific detection of low concentrations of oligonucleotide target was best achieved using a strategy that involved target–probe DNA hybridization in the solution with a subsequent modified “turn-off” GO capture and the quenching of the unhybridized probe. Using carefully formulated assay procedures that prevented GO aggregation, the preferential binding and quenching of the unhybridized probe were both achieved using 0.1% BSA, 0.065% SDS and 6 mM NaCl. This resulted in the sensitive measurement of the specific target–probe complexes remaining in the solution. The fluorescein-conjugated single stranded probe (FAM–ssDNA) exhibited linearity to cDNA hybridization with concentrations in the range of 1–8 nM, with a limit of detection equivalent to 0.1 pmoles of target in 100 μL of assay mix. We highlight a general approach that may be adopted for oligonucleotide target detection within complex solutions.
关键词： graphene oxide,optical DNA sensor,surfactants,fluorescence quenching
更新于2025-09-23 15:21:01
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Photoresponsive Structured Liquids Enabled by Molecular Recognition at Liquida??Liquid Interfaces
摘要： Using the host-guest molecular recognition at the oil-water interface, a new-type photo-responsive nanoparticle surfactant (NPS), is designed and prepared to structure liquids. With the help of a polymeric surfactant, the interfacial host-guest interactions can be significantly enhanced, leading to a rapid formation and assembly of a NP monolayer, and offering sufficient binding energy to hold the NPs in a jammed state. The assembly of the NPSs can be reversibly manipulated via a photo-switchable jamming to unjamming transition, endowing the interface, as well as the macroscopic assemblies, with responsiveness to the external trigger (photons). This study, for the first time, opens the pathway for the construction of multi-responsive, structured all-liquid systems by introducing host?guest chemistry, showing promising potential applications in encapsulation, delivery systems, and unique microfluidic devices.
关键词： self-assembly,liquid-liquid interfaces,host-guest chemistry,Structured liquid,nanoparticle surfactants
更新于2025-09-23 15:19:57
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Self-assembling nanoprobes that display two-dimensional fluorescent signals for identification of surfactants and bacteria
摘要： The imidazolium-pyrene self-assembling nanoprobes can rapidly discriminate four types of surfactants. The surfactants disassembled the probes to turn on significant fluorescence and transform between a pyrene monomer and an excimer, generating a two-dimensional analysis map. The probes were further used to identify different bacterial species.
关键词： fluorescence,surfactants,nanoprobes,self-assembly,bacteria
更新于2025-09-19 17:15:36