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Fluorescent brightening agent VBL-based waterborne polyurethane dye (VBL-WPU) was synthesized by incorporation of VBL into waterborne polyurethane chains. The expected structure of polymeric fluorescent brightening agent was confirmed by FT-IR and UV-vis spectra. The molecular weight, average particle sizes and the contents of VBL segments in VBL-WPU were investigated. This polymeric dye exhibited intriguing optical behaviors. The absorption and emission maxima of VBL-WPU showed obviously hypsochromic shift in comparison with those of VBL. The fluorescence intensity of the polymer was prominently enhanced comparing with VBL because of the changes of micro-circumstance of VBL. Furthermore, the fluorescence of VBL-WPU was not sensitive to hydroquinone quencher.  相似文献
A novel ion-bonded discotic complex was prepared from 2,3,6,7,10,11-hexakis(N,N-dimethylaminopropylaminocarbonylmethoxy)triphenylene (HDTP) and 4′-dodecyloxybiphenyl-4-carboxylic acid (DBC) by ionic self-assembly (ISA) route and characterized by Fourier transform infrared (FTIR) spectrum. We found that the complex can self-assemble into stable gels in aromatic hydrocarbons. Nanofibers with diameters of 50–130 nm were observed in the gels by transmission electron micrograph (TEM). The FTIR data in conjunction with UV–vis and fluorescence spectra suggested that the aggregation of the complex into elongated fibers in solution was induced by a directional extended network of hydrogen bonds and π–π interactions. Based on the experiment analysis, we proposed a tentative model of the self-assembly of this two-component gel-phase material.  相似文献
In this paper, PMMA/ZnO nanocomposites have been prepared by a very simple, facile and versatile chemical approach. The prepared PMMA/ZnO nanocomposites possess no color, high transparency, good thermal stability, UV-shielding capability, luminescence and homogeneity. The chemical process involved solution mixing of ZnO nanoparticles dispersed in DMAc with the Polymethylmethacrylate (PMMA) matrix dissolved in the same solvent. The effect of ZnO content on the physical properties of the PMMA matrix is investigated by X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, UV–Vis absorption and photoluminescence spectroscopy. It was found that pure hexagonal ZnO nanoparticles with an average particle size of 4–8 nm were homogeneously dispersed in the PMMA matrix. A significant improvement in thermal properties was observed with the incorporation of 1.0 wt% ZnO nanoparticles. The prepared nanocomposite films are highly transparent and a clear excitonic peak is observed in their absorption spectra. Measurement of room temperature photoluminescence spectra shows intensive near-band edge emission peak at 3.28 eV without any structural defects for a nanocomposite film with a filler content of 1.0 wt%.  相似文献
We developed a novel temperature and pH dual-responsive supramolecular system in which the aggregation and disaggregation of polydiacetylene/silver (PDA/Ag) hybrid nanocrystals can be mediated by environmentally responsive threading and dethreading processes of polypseudorotaxane. The PDA/Ag hybrid nanocrystals provide a nonlinear optical (NLO) property. The host?Cguest interaction between poly(ethylene glycol) (PEG) and cyclodextrin (CD) cavities on the surface of the hybrid nanocrystals causes the PDA/Ag hybrid nanocrystals to be sufficiently close to each other for providing an enhanced surface plasmon resonance and a corresponding NLO effect. NLO switching of the colloidal materials can be easily realized by varying temperature and pH. The facile preparation procedures and their response to the surrounding media render these novel hybrid colloidal materials potential candidates for applications in sensors, catalysis and optical/electronic devices.  相似文献
以在50 oC水溶液中析出的聚(N-异丙基丙烯酰胺) (PNI-PAM)聚集体作为软模板,使正硅酸乙酯吸附在PNIPAM聚集体表面进行水解缩合,原位生成二氧化硅包裹PNIPAM的核壳结构微球;进一步冷却至室温使PNIPAM溶解在水中除去内核,从而成功合成出SiO2中空微球.实验表明,只有在足够的PNIPAM和正硅酸乙酯含量以及正硅酸乙酯水解时间下,才能形成稳定的SiO2中空微球.用TEM、SEM和FTIR对合成的SiO2中空微球进行了表征,结果表明,微球尺寸为150 nm左右,并且由于PNIPAM上酰胺基团和正硅酸乙酯水解出来的硅醇间具有静电相互作用,使得SiO2壳层上依然有PNIPAM残留.  相似文献
通过种子乳液聚合合成核壳结构的聚甲基丙烯酸甲酯/聚苯乙烯(PMMA/PS)复合微球,通过酸碱溶胀法进一步制备出次微米级的PS中空微球. 将此中空微球作为微反应器,使在ZnO纳米粒子前驱体溶液中溶胀, 最终ZnO纳米粒子在PS中空微球中原位生成. 实验表明, 组成ZnO纳米粒子前驱体溶液的两种组 分(CH3COO)2Zn和LiOH的滴加顺序不同对最终生成的ZnO纳米粒子的尺寸和负载效率有很大的影响,但并不改变ZnO纳米粒子的晶型. 复合物的光致发光和UV-Vis吸  相似文献
利用在水相中原位生成的聚脲甲醛沉淀吸附在可见紫外光固化组份构成的油相表面,制备了包覆自修复剂的脲醛树脂(PUF)微胶囊. 光学显微镜及SEM表明,PUF微胶囊尺寸为118~663 μm,与PUF 形成过程中的搅拌速度有关. 在中等搅拌速度(600 r/min)时,可以得到最高的包覆率(97.52wt%)和产率(65.23wt%). 将此微胶囊掺入水性聚氨酯乳胶中制成的涂层表面受损后,在紫外光照射下可以进行自修复,具有优异的金属防腐蚀性能.  相似文献
流体在微流通道中形成剪切流场(低雷诺数).不同于宏观体系,由于剪切力和表面张力的竞争作用,产生的液滴在微尺度下的微流通道中形成特殊的排列现象---周期性类似“晶格”排列现象.设计了新型流动聚焦型微流控芯片,分析研究在微流体系中液滴周期性图案化排列和转变机理性,液滴排列模式受两方面因素影响:水油两相的流速比值和微通道尺寸.当微通道宽度为250或300 μm时,液滴形成单层分散,双层和单层挤压排列.当微通道宽度为350 μm 时,液滴会形成单层分散到三层排列到双层挤压最后到单层挤压排列.当出口通道宽度增加到400 μm时,甚至出现了液滴四层排列的现象.同时研究了各个液滴排列模式的“转变点”.  相似文献
合成了具有不同功能化的聚苯乙烯树脂,利用石英晶体微天平对树脂和微囊藻毒素相互吸附作用进行实时监测和研究.研究发现,吸附的pH和表面性质对于吸附量有重要的影响,而温度影响不大,中性pH氨基树脂对微囊藻毒素的吸附效果最好  相似文献
Photoluminescence of Eu(TTA)3DPBT (TTA=thenoyltrifluoro-acetonate DPBT=2-(N,N-diethylanilin-4-yl)-4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine) in toluene and PMMA thin film are measured with excitation at 350 and 404 nm, respectively, and analyzed using Judd-Ofelt theory. Under excitation at 350 nm, it is found that Eu(TTA)3DPBT in toluene has a larger Ω2 value (14.33×10−20 cm2) than that (12.70×10−20 cm2) of Eu(TTA)3Phen (Phen=1,10-phenanthroline) in the same solvent, and has a smaller Ω2 value (12.70×10−20 cm2) in PMMA than that (Ω2=14.09×10−20 cm2) of Eu(TTA)3Phen in PMMA. At the same time, it can be seen that under excitation at 350 nm Ω2 value of Eu(TTA)3DPBT in toluene is larger than that in PMMA. Excited by 404 nm, Ω2 of Eu(TTA)3DPBT obtained in toluene and in PMMA are the same as that excited at 350 nm. The transition probability (A), emission cross-section (σ) and the fluorescence branching ratio (β) are also evaluated. The lifetime of 5D0 metastable state is measured on 350 and 404 nm excitation, respectively. For the former situation, it is 455 μs in toluene and 640 μs in PMMA, for the latter it is 460 μs in toluene and 664 μs in PMMA. By comparing absorptions with excitations, it can be found that DPBT is more efficient than TTA as an energy donor. Phosphorescence spectra are also measured to estimate the lowest triplet level and analyze the energy transfer for DPBT and TTA, from which it is found that the energy transfer from TTA to DPBT occurs in the luminescent process.  相似文献
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