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UV/thermal dual curing of tung oil-based polymers induced by cationic photoinitiator
摘要： With the increasing shortage of petroleum-based resources, the exploitation and application of the polymers derived from the renewable resources has becomes increasingly important for the industrial development. In this work, in order to promote the direct application of tung oil in the coating ?eld, the tung oil-based polymers with the excellent mechanical properties by using cationic photoinitiator as the “green” initiator were prepared. The cationic polymerization mechanism and the optimal polymerization conditions of methyl eleostearate (ME) induced by triarylsulfonium salt (TAS) are characterized via the nuclear magnetic resonance spectroscopy. The e?ects of di?erent monomers on the properties of tung oil-based polymers and the post curing behaviors of the polymers are studied by dynamic mechanical test and microtensile test. The results display that the heating treatment after UV irradiation is necessary and favorable for the cationic polymerization of ME induced by TAS. And the optimal reaction condition is 500 W of irradiation energy, 5 wt% of initiator concentration, 60 min of irradiation time, 100 °C of heating temperature and 3 h of heating time. Moreover, tung oil-based polymers with good hydrophobicity can be obtained under the optimal reaction condition. In addition, adding 20 wt% divinylbenzene and 10 wt% styrene to the tung oil can e?ectively increase the mechanical properties and glass transition temperatures (Tg) of tung oil-based polymers.
关键词： Dual curing,Triarylsulfonium salts,Cationic polymerization,Tung oil-based
更新于2025-11-14 15:14:40
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The combination of Raman imaging and LIBS for quantification of original and degradation materials in Cultural Heritage
摘要： Quantification with nondestructive techniques is not very well developed in the field of Cultural Heritage despite its interest. In the last decades, several works have been published using Raman spectroscopy for quantifying. However, depending on the methodology used, the information provided by this technique is not complete, and the results could lead to misunderstanding when dealing with unknown samples. In this work, a novel double quantification using Raman imaging (its representativeness would be higher than point-by-point analysis) and Laser Induce Breakdown Spectroscopy (LIBS) analyses is presented for analysis of Cultural Heritage samples. Several dolomitic marble samples, with some calcite impurities, covered or not by a calcium oxalate (whewellite, CaC2O4·H2O) layer were analysed in order to optimize the novel methodology. The agreement between the quantitative results from the independent analyses of the Raman Image data and the LIBS data is consistent within the uncertainty arising from both techniques. Further, the same methodology was applied on the same samples but using point-by-point Raman analysis with portable instruments, and portable LIBS information, showing again a great agreement between them and with the results obtained using the laboratory instruments.
关键词： hydrated salts,quantification,Cultural Heritage,LIBS,Raman imaging
更新于2025-09-23 15:23:52
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Amine salts assisted controllable synthesis of the YVO4:Eu3+ nanocrystallines and their Luminescence properties
摘要： The Eu3+ doped YVO4 nanocrystallines with various morphologies were successfully synthesized by an amines (TETA, ETA and EDA) assisted hydrothermal process. By rationally adjusting the adding amount of TETA, ETA and EDA, the trepang-like, globular-like and pineapple-like Eu3+ doped YVO4 nanostructures can be conventionally obtained. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD patterns indicate that these samples are all of the tetragonal structure. The SEM and TEM results show that the amines additives play an important role in morphology formation. Furthermore, the fluorescence properties of those samples are also systematically studied. Under the excitation of 280 nm, Eu3+ doped YVO4: nanostructures emit strong red fluorescence due to the transitions of 5D1-7F1 and 5D0-7FJ (J =1, 2, 3 and 4) of Eu3+ ions. The intensity of red fluorescence is related to not only the concentrations of Eu3+, but also the types of adding amines. The effective luminescence lifetimes of the trepang-like Y0.9Eu0.1VO4 nanocrystallines, the globular-lik and pineapple-like Y0.95Eu0.05VO4 nanocrystallines are 0.91 ms, 1.02 ms and 1.14 ms, respectively. It is believed that this study is beneficial to promote the development of color display industry.
关键词： hydrothermal,Amine salts,luminescence lifetimes,Eu3+ doped YVO4,fluorescence properties
更新于2025-09-23 15:23:52
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Measurement of Forces between Supported Cationic Bilayers by Colloid Probe Atomic Force Microscopy: Electrolyte Concentration and Composition
摘要： The interactions between supported cationic surfactant bilayers were measured by colloidal probe atomic force spectroscopy, and the effect of different halide salts was investigated. Di(alkylisopropylester)dimethylammonium methylsulfate (DIPEDMAMS) bilayers were fabricated by the vesicle fusion technique on muscovite mica. The interactions between the bilayers were measured in increasing concentrations of NaCl, NaBr, NaI, and CaCl2. In NaCl, the bilayer interactions were repulsive at all concentrations investigated, and the Debye length and surface potential were observed to decrease with increasing concentration. The interactions were found to follow the electrical double layer (EDL) component of DLVO theory well. However, van der Waals forces were not detected; instead, a strong hydration repulsion was observed at short separations. CaCl2 had a similar effect on the interactions as NaCl. NaBr and NaI were observed to be more efficient at decreasing surface potential than the chloride salts, with the efficacy increasing with the ionic radius.
关键词： supported bilayers,DLVO theory,Debye length,surface potential,halide salts,colloidal probe atomic force spectroscopy
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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Electrochromic behavior of films and ?smart windows? prototypes based on π-conjugated and non–conjugated poly(pyridinium triflate)s
摘要： This study is focused on two electrochromic poly(pyridinium triflate)s. They are aromatic rigid-rod polymer PV1 and PV12 containing alkyl linkages. Electrochromic behavior of both polymers was comparatively investigated by employing a three-electrode cell and ?smart windows? prototypes. The electrochromic properties of polymer films were examined by electrochemical and spectroelectrochemical methods. Polymers with π-conjugate and non-conjugate structure demonstrate reversible redox process accompanied by a reversible color change both in three-electrode cell and electrochromic device (ECD). In general, introduction of the non-conjugated spacers to the PV12 backbone structure leads to deterioration in the optical contrast and switching time in comparison with π-conjugated PV1. The same effect was also detected for ECD. The reason behind this is thought to be a complication of electron transport in the system due to non-conjugated PV12 backbone structure.
关键词： Electrochromic polymers,Poly(pyridinium) salts,Conjugated polymer,Cyclic voltammetry,Electrochromism
更新于2025-09-23 15:22:29
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The luminescent properties of GdAlO<SUB align="right">3:Tb<SUP align="right">3+</SUP> phosphors based on molten salts addition
摘要： The (Gd1–xTbx)AlO3 (x = 0–0.12) were obtained through ammonium bicarbonate co-precipitation technology. The pure-phase (Gd1–xTbx)AlO3 with good dispersion could be obtained at relatively lower temperature of 1,000°C. Under optimum UV excitation into 275 nm, the photoluminescence (PL) spectra display a series of 5D4–7FJ transitions of Tb3+ in (Gd1–xTbx)AlO3 system with the strongest green emission at ~546 nm. The overlapping between 8S7/2–6IJ intra f-f transition of Gd3+ and 4f8–4f75d1 transition of Tb3+ at 275 nm suggesting the Gd3+ → Tb3+ energy transfer, and the quenching contents of Tb3+ was found to be ~10 at%. The luminescent property of GdAlO3:Tb3+ phosphor could be further improved with molten salt incorporation. The optimal composition of molten salts was determined to be the mixture of NaCl/Na2SO4 (5 wt% NaCl), and the mass ratio of mixture molten salts to precursor was 2:1. The relationship between the luminescent property and molten salts composition were studied in detail.
关键词： energy transfer,GdAlO3:Tb3+ phosphor,molten salts,luminescent property
更新于2025-09-23 15:22:29
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Porphyrins as Photoredox Catalysts in Csp2-H Arylations: Batch and Continuous Flow Approaches
摘要： We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different α-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron-donor in the triplet excited-state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. Scope, a two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts.
关键词： Diazonium Salts,Photoredox Catalysts,Porphyrins,Batch and Continuous Flow,Csp2-H Arylations
更新于2025-09-23 15:21:01
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Detecting Laser-Volatilized Salts with a Miniature 100-GHz Spectrometer
摘要： Rotational transitions are unique identi?ers of molecular species, including isotopologues. This article describes the rotational detections of two laser-volatilized salts, NaCl and KCl, made with a miniature Fourier transform millimeter-wave (FTmmW) cavity spectrometer that could one day be used to measure solid composition in the ?eld or in space. The two salts are relevant targets for icy moons in the outer solar system, and in principle, other molecular solids could be analyzed with the FTmmW instrument. By coupling the spectrometer to a collisionally cooling laser ablation source, (a) we demonstrate that the FTmmW instrument is sensitive enough to detect ablation products, and (b) we use the small size of the FTmmW cavity to measure ablation product signal along the carrier gas beam. We ?nd that for 532 nm nanosecond pulses, ablated molecules are widely dispersed in the carrier-gas jet. In addition to the miniature spectrometer results, we present several complementary measurements intended to characterize the laser ablation process. For pulse energies between 10 and 30 mJ, the ablation product yield increases linearly, reaching approximately 1012 salt molecules per 30 mJ pulse. Using mass spectrometry, we observe Li+, Na+, and K+ in the plumes of ablated NaCl, KCl, and LiCl, which implies dissociation of the volatilized material. We do not observe salt ions (e.g., NaCl+). However, with 800 nm femtosecond laser pulses, the triatomic ion clusters Li2Cl+, Na2Cl+, and K2Cl+ are produced. Finally, we observe incomplete volatilization with the nanosecond pulses: some of the ejecta are liquid droplets. The insights about ablation plume physics gleaned from these experiments should guide future implementations of the laser-volatilization technique.
关键词： KCl,Fourier transform millimeter-wave,FTmmW,rotational transitions,NaCl,mass spectrometry,outer solar system,icy moons,laser-volatilized salts,laser ablation
更新于2025-09-23 15:19:57
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Photoredox Arylation of Enol Acetates via Porphyrin Catalysis
摘要： Photoredox Arylation of Enol Acetates via Porphyrin Catalysis
关键词： diazonium salts,porphyrins,photoredox arylation
更新于2025-09-19 17:15:36