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Photo-thermal Dual Curing of Polysilane/diarylfluorene Blends -Fabrication of Films with High and Tunable Refractive Indices-
摘要： We have developed the crosslinked films of diphenyl- or dinaphthylfluorene having acryl units with polymethylphenylsilane in the presence of a photoradical initiator upon irradiation at 405 nm with thermal treatments at around 100 oC. The photopolymerization of the acrylates effectively enhanced by the photo-thermal dual curing technique. Polysilane moieties were incorporated into the film by the termination reaction between the acrylate radicals and Si radicals generated by the slight photo-decomposition of the Si-Si bonds. We have successfully fabricated the films with high refractive indices (nD: 1.62) and the refractive index values were tunable by irradiation at 254 nm by the effective decomposition of the Si-Si bonds of the polysilanes. The reaction mechanism is discussed based on real-time FT-IR measurements. The prepared films have a high thermal stability (temperature for 5% weight loss, Td5: 300 oC).
关键词： High refractive index,Photo-thermal dual curing,Polysilane,Acryl,High thermal stability,Fluorene
更新于2025-09-23 15:22:29
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Effects of different molecular chain lengths and side groups on structure and property of UV-curable waterborne cathodic electrophoretic deposition coatings
摘要： A series of UV-curable waterborne cathodic electrophoretic deposition (CED) coatings with various structures were successfully developed by introducing modified acrylic monomer with different molecular chain lengths and side groups. The length of linear chain of the modified monomer had little effect on phase separation of acrylic polymer and easily formed homogeneous structure. Owing to the longer molecular chains, the pencil hardness decreased from 2H to H and the glass transition temperature reduced to 77.7 °C. The hard side groups of the modified monomer in CED coatings exhibited opposite characteristics resulting from the steric hindrance of the rigid groups and the crosslinking network, which were more likely to exhibit partial phase separation. Therefore, the stronger rigidity of the molecular structure improved the particle size to 122.42 nm, the smoothness of the CED cured film and surface contact angle decreased. And the morphology of the films became rough and surface contact angle decreased. Besides, the adhesive force and flexibility of the films could be excellent. The surface rust of the modified CED film is not remarkable under salt spray test. The photopolymerization rate (Rp) and the double bond conversion were evaluated. It was found that the Rp and the conversion obviously decreased with increasing rigid groups in acrylate molecular chains. However, the maximum decomposition temperature of it was higher than the other samples. The residue char yield (Yc) was 5.24 wt%. The stronger rigidity of the molecular structure had better thermal stability and mechanical properties.
关键词： Cathodic electrophoretic deposition coatings,Thermal stability,Photopolymerization rate,Molecular structure
更新于2025-09-23 15:22:29
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Novel Ca20Al26Mg3Si3O68:Ce3+,Tb3+ phosphors: preferential site occupation, color-tunable luminescence and device application
摘要： A novel luminescence material of emitting color-tunable Ca20Al26Mg3Si3O68(denoted as CAMSO):Ce3+,Tb3+ phosphors have been synthesized via the high temperature solid-phase reaction process. The crystal cell structure, photoluminescence properties and application performance such as thermal stability and LED device performance of the phosphors were researched in detail. CAMSO:Ce3+,Tb3+ phosphors showed multi-color with the different concentration of Ce3+ and Tb3+ ions. Although the concentration of Ce3+ ions was settled and there was the existence of energy transfer from Ce3+ to Tb3+ ions, it was found that Ce3+ ions’ blue light emission intensity showed abnormal increasing with the increase of Tb3+ ions doping concentration. The irregular phenomenon was discussed in detail. The phosphor CAMSO:0.2Ce3+, 0.1Tb3+ photoluminescence emission intensity motivated by 374nm at 150oC retained about 81% of that measured at room temperature, which demonstrating the good thermal and color stability of the sample. In addition, the white LED lamps were fabricated through mixing the sample CAMSO:0.2Ce3+,0.2Tb3+ and the commercial phosphor CaAlSiN3:Eu2+ and their performance has been measured. The results show that this series of phosphors could be excellent candidates for the application of UV-excited w-LEDs.
关键词： thermal stability,abnormal luminescence,tunable color,multi-crystallographic sites
更新于2025-09-23 15:22:29
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Synthesis and Optical Properties of Dipolar Thiazole Derivatives Incorporating Nitro and Amino Substituents
摘要： We report the synthesis of two dipolar thiazole derivatives functionalized with nitro group as electron acceptor and amino group as electron donor, in order to study their optical properties in the UV-vis range. Their structures were verified by 1H NMR, 13C NMR, HRMS and FT-IR. The resulted thiazole derivatives have good thermal stability with decomposition temperature, Td of 320.20 °C and 284 °C for compounds 1 and 2 respectively. The absorbance bands of compound 2 in the UV-vis range are more red-shifted than that of compound 1 which made compound 2 could have high potential as a great organic NLO material.
关键词： NLO,Push-pull,Thiazole derivative,Thermal stability,Dipolar thiazole
更新于2025-09-23 15:22:29
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Preparation and characterization of UV-curable fluorine-silicon block urethane acrylates for application in release films
摘要： A series of fluorine-silicon block urethane acrylates (PSi-FMPG-IPDI-HEMA) were synthesized from hydroxypropyl-terminated polysiloxane (PSi), newly-prepared fluorodiol (FMPG), isophorone diisocyanate (IPDI) and hydroxyethyl methacrylate (HEMA). Their molecular structures were characterized by Fourier transform infrared and gel permeation chromatography. The compatibility of the oligomers with HFMA was validated using UV–vis transmittance analysis. The thermal stability, water and chemical resistance, contact angles and anti-adhesive performance of the films were measured. It was found all the films had good thermal properties, and excellent water and chemical resistance. The FMPG content affected the surface energy and anti-adhesive performance of the films. The films with more FMPG presented lower surface energy, lower peel strength, and higher residual adhesion. More importantly, the release films designed based on the fluorine-silicon block urethane acrylates had tremendous application potential.
关键词： Anti-adhesive performance,Surface energy,Fluorine-silicon block urethane acrylates,Thermal stability
更新于2025-09-23 15:22:29
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Improved thermal stability of Y3Al5O12:Ce3+ phosphor by SiO2 coating
摘要： In this paper, a heterogeneous precipitation method was adopted to coat a SiO2 layer on the surface of Y3Al5O12:Ce3+ phosphor. The surface morphologies, crystal phases, defect concentrations, luminescent properties and thermal stability of coated phosphors were investigated and compared with those of uncoated phosphor. A compact and homogeneous SiO2 layer on the surface of phosphor was determined by SEM-EDS, TEM, XRD and FT-IR results. Two thermoluminescent peaks were found at 112 oC and 248 oC on the thermoluminescence spectrum. Their intensities decreased slowly with the increasing coating amounts. It indicated that their corresponding defect concentrations were gradually reduced. Improved thermal stability was obtained by SiO2 coating in spite of a slight weakening of the emission intensity. The optimum theoretical coating amount was identified as 4%. Moreover, a structural modification mechanism on improved thermal stability of SiO2 coated Y3Al5O12:Ce3+ was proposed.
关键词： Y3Al5O12:Ce3+ phosphor,thermal stability,coating,structural modification mechanism
更新于2025-09-23 15:22:29
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Experimental and computational studies on induced thermochromic effect and re-entrant smectic phase in linear double hydrogen-bonded binary liquid crystal mixtures
摘要： Design and synthesis of the hydrogen-bonded liquid crystalline (HBLC) mixtures are accomplished from diglycolic acid and 4-n-alkoxybenzoic acid (n = 9–12). Spectroscopic characterization such as UV–Vis, FT-IR, and DSC has supported the presence of molecular geometry of HBLC mixtures. Thermochromic effect is analyzed for the polarizing filter applications. Induced new phases (Smectic X and Smectic Cr) and their transitions are confirmed through DSC along with its corresponding optical textures using polarizing microscope. Furthermore, the induced re-entrant smectic ordering due to the lone pair to π* transition is reported using density functional theory (DFT) studies. Dipole moment studies (DFT) clearly give a strong evidence of the existence of nematic and smectic phases due to the monopole–dipole interaction in the present HBLC mixtures. Band gap of the present HBLCs is 5.175 eV, which is calculated by the HOMO–LUMO analysis and is validated using experimental observations. Liquid crystal parameters such as transition temperature, enthalpy values, stability factor and tilt angles are reported.
关键词： thermal stability,Nematic,DFT,re-entrant,thermochromic
更新于2025-09-23 15:22:29
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P-1.3: The conductivity modulation of amorphous zinc tin oxide thin film by Ar plasma treatment
摘要： We propose a method to form low-resistance amorphous zinc tin oxide thin film (a-ZTO) by Ar plasma. The results show that the Ar plasma treatment can effectively decrease the resistivity of the a-ZTO. The ZTO film treated with Ar plasma at suitable time and moderate operating power, exhibits a low sheet resistance of 2.3 kΩ/□. With the help of PECVD-SiOx coverage layer, the sheet resistance of Ar-plasma treated ZTO is enhanced and increases only one order of magnitude after annealing at 230 ℃. As a result, an optimized Ar plasma treatment for fabrication of low-resistance a-ZTO film is presented.
关键词： amorphous zinc tin oxide,thermal stability,Ar plasma treatment,low-resistance
更新于2025-09-23 15:22:29
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Simultaneously enhanced far-red luminescence and thermal stability in Ca3Al4ZnO10:Mn4+ phosphor via Mg2+ doping for plant growth lighting
摘要： Non-rare-earth-based Ca3Al4ZnO10:Mn4+,Mg2+ (CAZO:Mn4+,Mg2+) phosphors with admirable luminescence performance and great potential as far-red light source for plant growth light-emitting diodes (LEDs) were reported in this paper. The concentration-dependent optical properties of the as-prepared phosphors were investigated in detail. Under ultraviolet-light excitation at 358 nm, the composition-optimized CAZO:0.4%Mn4+,14%Mg2+ phosphor showed an intense broad far-red emission band in the 625-830 nm wavelength range with a maximum at 714 nm, which was due to the 2Eg→4A2g transition of Mn4+ ions. The luminescence intensity of the CAZO:0.4%Mn4+,14%Mg2+ phosphor was about 1.82 times higher than that of CAZO:0.4%Mn4+ phosphor, and the corresponding mechanism for the luminescence enhancement via Mg2+ doping was studied. Amazingly, the internal quantum efficiency of the CAZO:0.4%Mn4+ phosphor was increased from 31 to 60% after co-doping 14 mol% Mg2+. The CAZO:0.4%Mn4+,14%Mg2+ phosphor also showed enhanced thermal stability compared with the CAZO:0.4%Mn4+ counterpart. It was found that, for CAZO:0.4%Mn4+,14%Mg2+ phosphor, the emission intensity at 423 K (150 oC) was about 51% of that at 303 K (30 oC), while the corresponding activation energy was determined to be 0.245 eV.
关键词： thermal stability,plant growth,phytochrome,far-red emissions,LEDs.,Mn4+ ions
更新于2025-09-23 15:22:29
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Effect of copper doping on the crystallization behavior of TiSbTe for fast-speed phase change memory
摘要： In this study, Ti-Sb-Te (TST) alloy doped with Cu has been proposed to enhance the phase change and electrical properties of TST. The formation of Cu-Te bond was suggest to be responsible for the improved thermal stability of the Cu0.28(Ti0.09Sb0.38Te0.53)0.72 (Cu0.28TST) film. Cu0.28TST -based phase change memory cell can be triggered by a 5 ns electric pulse. Such fast speed was asscribed to its growth-dominated crystallization mechanism and the precipitation of Sb in the crystallization process. Furthermore, an endurance cycles up to 105 could be achieved in the memory cell.
关键词： nanocomposite,thermal stability,rapid transition,thin film
更新于2025-09-23 15:22:29