黄光类水滑石的制备、表面改性及应用

采用共沉淀法合成了荧光类水滑石材料,该材料在470 nm蓝光激发下可发出黄色荧光(557 nm),采用硅烷偶联剂对其进行表面改性,探讨了表面改性对黄光类水滑石的发光性能、结构及热稳定性的影响。将改性黄光类水滑石与GaN基蓝光芯片封装后制得了白光LED。研究结果表明,改性的黄光类水滑石是制作白光LED可供选用的黄色发光材料。本文成功地将低温一步法制备得到的金属有机配合物/无机纳米杂化材料应用于LED,拓展了LED用荧光粉的选用范围。     

黄光类水滑石的制备、表面改性及应用

采用共沉淀法合成了荧光类水滑石材料,该材料在470 nm蓝光激发下可发出黄色荧光(557 nm),采用硅烷偶联剂对其进行表面改性,探讨了表面改性对黄光类水滑石的发光性能、结构及热稳定性的影响。将改性黄光类水滑石与GaN基蓝光芯片封装后制得了白光LED。研究结果表明,改性的黄光类水滑石是制作白光LED可供选用的黄色发光材料。本文成功地将低温一步法制备得到的金属有机配合物/无机纳米杂化材料应用于LED,拓展了LED用荧光粉的选用范围。     

高荧光性含锌类水滑石研究

本研究将适量锌离子(II)取代镁铝水滑石中的镁离子(II), 以及将一定量的8-羟基喹啉(8-hydroxyquinoline)分散于镁铝水滑石层间的亲油性阴离子中, 使与其板层表面上的锌离子配位, 经共沉淀法, 合成、组装得到一类迄今未见报道的具高荧光性的类水滑石(Zn-HTLC)荧光材料. 采用荧光光谱、红外光谱、紫外光谱、X射线衍射和热分析等对其进行了表征. 研究表明, 这种类水滑石在紫外光下可发出强烈的蓝绿色荧光(501 nm), 荧光强度高达4.5×10⁵ a.u., 说明锌离子(II)分散于类水滑石的氢氧化镁板层中, 可有效防止发光结构单元的荧光猝灭, 而且溶于层间阴离子中的配体与板层上的锌离子(II)配位所形成的特殊组装结构, 增强了发光中心的不对称性, 也是其具有高荧光性的可能原因. 热分析结果显示, 这种类水滑石耐热性强, 有望应用于各种功能性荧光材料.     

阴-非离子表面活性剂复合改性水滑石的表面性质研究

采用十二烷基苯磺酸钠(SDBS)、吐温-80(Tween-80)及两种表面活性剂复合改性镁铝水滑石,得到SDBS-LDHs,TweenLDHs及SDBS/Tween-LDHs 3种改性水滑石。利用反相气相色谱法(IGC)对样品进行表面性质的研究,定量计算了表面吸附自由能(ΔG0)和表面能色散组分(γs d)。结果表明,改性材料的ΔG0与γs d值均比未处理的镁铝水滑石小,其中阴-非离子表面活性剂复合改性后的水滑石的ΔG0与γs d值最小,说明阴-非离子表面活性剂复合改性水滑石较单一改性水滑石更有利于提高材料的稳定性。此外,各类水滑石的γs d值均随着温度的升高而减小,因此,在制备聚合物/水滑石类材料时,可以利用提高温度来改善其与聚合物的相容性。     

表面活性剂和硅烷偶联剂复合改性水滑石的表面性质

采用十二烷基硫酸钠(SDS)和3-氨丙基三乙氧基硅烷(KH550)、乙烯基三乙氧基硅烷(KH151)对锌铝水滑石进行有机改性,得到插层改性与表面改性结合的聚合物/锌铝水滑石复合材料。XRD、FTIR及计算机模拟的分析结果表明,SDS已垂直插入水滑石层间,层间距达到2.70 nm,KH550及KH151只是覆盖在水滑石表面,与层板表面羟基进行偶联。反相气相色谱的结果表明,复合材料的表面能(γsd)均比水滑石小,其中KH151-SDS-LDHs及KH550-SDS-LDHs的表面能较接近,由材料表面的酸碱常数,判断出SDS-LDHs表面趋于两性,KH151-SDS-LDHs及KH550-SDS-LDHs表面偏碱性,适于做碱性聚合物的填料。     

超声波作用下离子交换改性水滑石对PP性能的影响

采用超声波离子改性水滑石,并将其添加在等规聚丙烯材料中。运用X射线衍射仪技术(XRD)、傅里叶红外光谱(ATIR)、差示扫描量热(DSC)、偏光显微镜(POM)、扫描电镜(SEM)等方法测试表征了水滑石通过超声离子改性前后对等规聚丙烯材料结构的影响。结果表明,超声离子改性的水滑石能扩大水滑石层间距,促进和增加改性基团的插层率,能改善其在等规聚丙烯中的分散性,对等规聚丙烯起到明显的异相成核作用,细化其晶粒,同时能够增强和增韧等规聚丙烯材料。     

一种新型黄色荧光类水滑石材料的制备及表征

用适量的Zn(Ⅱ)取代镁铝水滑石中的Mg(Ⅱ),同时将一定量的2-对联苯基-8-羟基喹啉分散到类水滑石层间的亲油性阴离子中,使其与层板表面上的Zn(Ⅱ)配位,用一步法合成、组装得到一类新型黄色荧光类水滑石复合物(Zn-(HQ-4-biPh)-HTlc)。采用荧光光谱、红外光谱、X射线衍射、扫描电子显微镜和热分析等对其进行了表征。研究结果表明,Zn-(HQ-4-biPh)-HTlc在蓝光(481 nm)激发下可发出黄色荧光(554 nm),与其相应的含锌配合物(Zn[2-(p-biph)-8-Q-O]2)相比,不仅可节省配体用量,而且具有更高的发光强度和更好的热稳定性,有望在白光LED等光电领域得到应用。     

表面预处理对镁铝水滑石结构性质和缓释性能影响

以Mg-Al-NO3水滑石(LDHs)为载体,将5-氟尿嘧啶(5-FU)通过离子交换法插入其层间,得5-FU/LDHs缓释材料。并对水滑石表面进行弱酸预处理改性,利用XRD、FTIR、TG-DSC、SEM和零电荷点(pHPZC)等表征手段,考察酸预处理对水滑石表面化学性质及微观结构的影响。结果表明,5-FU/LDHs的层间距从0.858 nm扩大到1.064 nm,层间5-FU2阴离子与主体层板通过氢键与静电作用,以呈一定角度单层交替排列于层间。酸预处理的水滑石粒径变小,层板正电荷密度增大。5-FU的释放机理是物理扩散、离子交换和药物溶解等协同作用,酸预处理可提高水滑石的缓释性能和稳定性。     

水滑石阻燃剂的离子改性研究进展

由于水滑石具有层板阳离子可调控、层间阴离子可交换、酸碱性等独特的性能,在医药、离子交换、催化、材料阻燃等领域备受研究者关注。特别是水滑石用作阻燃材料时,具有无卤、无毒、不产生有毒和腐蚀性气体、阻燃和抑烟性能优良等突出优点,已成为当前材料阻燃领域研究的热点。然而,水滑石也存在热稳定性较差、容易聚集、分散性较差等缺点,故国内外学者开展了水滑石阻燃剂改性的系列研究。本文阐述了近年来利用Ca~(2+)、Mg~(2+)、Al~(3+)等阳离子以及BO_3~(3-)、SiO_3~(2-)等阴离子对水滑石阻燃剂进行改性等方面的研究进展,并对水滑石在生物质材料阻燃、低成本水滑石阻燃剂的合成、水滑石协效阻燃剂的研究、水滑石阻燃剂工业化生产新工艺与设备、洁净化制备技术等方面的研究与应用前景进行了展望。     

Zn-Al类水滑石的荧光性质

报道了一种新的Zn-Al类水滑石的荧光现象, 即在没有任何荧光物质插层的情况下, Zn-Al类水滑石本身就具有荧光性质, 其最大激发波长位于375 nm, 最大发射波长处于443 nm, 显示的荧光为蓝色可见光. 这一光学功能的发现将有助于类水滑石在光学材料领域中的进一步应用.     

Synthesis and characterization of a strong-fluorescent Eu-containing hydrotalcite-like compound

A novel strong-fluorescent Eu-containing hydrotalcite-like compound (Eu-HTlc) was synthesized using the coprecipitation method, in which aluminum(III) was partially substituted by Europium (III) in the hydrotalcite-like layers, and thenoyltrifluoroacetone, 1,10-phenanthroline were dispersed into the anions in the interlayer region. The sample was characterized by XRD, XPS, FT-IR, ICP, TG-DSC, TEM and fluorescence spectra, and its composition and structure were determined. The results indicated that the sample exhibited a characteristic red light (614 nm). The fluorescent lifetime and fluorescence quantum yield of Eu-HTlc were measured to be respectively 893 μs and 66.44%, higher than those of Eu(III)-thenoyltrifluoroacetone-1,10-phenanthroline complex [Eu(TTA)₃phen]. The result of TG-DSC measurement showed the enhanced thermal stability of Eu-HTlc compared with that of MgAl-LDHs and Eu(TTA)₃phen. With excellent photoluminescent property and thermal stability, low contents of rare earth ions and ligands, the Eu-HTlc may become one of the novel fluorescent materials with potential applications.     

4,4′-双(4″,4″,4″-三氟代-1″,3″-二氧代丁基)联苯铕配合物的合成及发光性能

合成了2个新的配合物Eu2(btb)3(H2O)4(1)和Eu2(btb)3(phen)2(2)[H2btb=4,4′-双(4″,4″,4″, -三氟代 - 1″,3″-二氧代丁基)联苯, phen=1,10-邻菲罗啉]. 采用元素分析、红外光谱、紫外光谱和快原子轰击质谱表征了2个配合物的结构. 在近紫外光激发下, 配合物1和2都发射出强的铕离子特征红光. 对614 nm 红光进行监控, 其激发光谱在395 nm处具有最大的激发强度, 与InGaN芯片发射的近紫外光激发相匹配. 将配合物1和2与395 nm 发射的InGaN芯片进行组合制备了红色发光二极管. 在配合物和硅树脂的质量比为1∶25的情况下, 2个红色发光二极管的色坐标分别为x1=0.5210, y1=0.2285(配合物1); x2=0.5835和y2=0.2857(配合物 2), 位于标准的国际色坐标红色区域; 器件的发光效率分别为0.65和0.76 lm/W. 研究结果表明, 配合物1和2是制作白光二极管可供选用的红色发光材料.     

A novel orange phosphor of Eu-activated calcium chlorosilicate for white light-emitting diodes

Novel orange phosphor of Eu²⁺-activated calcium chlorosilicate was synthesized at 1273 K by conventional solid-state reactions under reductive atmosphere and investigated by means of photoluminescence excitation, diffuse reflectance and emission spectroscopies. These results show that this phosphor can be efficiently excited by the incident light of 300-450 nm, well matched with the emission band of 395 nm-emitting InGaN chip, and emits an intense orange light peaking at 585 nm. By combining this phosphor with a 395 nm-emitting InGaN chip, an intense orange light-emitting diode (LED) was fabricated. Under 20 mA forward-bias current, its CIE chromaticity coordinates are (0.486, 0.446). The dependence of as-fabricated orange LED on forward-bias current indicates that it shows excellent chromaticity stability and luminance saturation. These results show that this Eu²⁺-activated calcium chlorosilicate is a promising orange-emitting phosphor for near-ultraviolet (UV) InGaN-based white LED.     

四[4,4'-双(4",4",4"-三氟代-1",3"-二氧代丁基)邻三联苯]双核铕配合物的发光及其在发光二极管中的应用

合成了一个双核铕的配合物,[HN(CH3CH2)3]2[Eu2(bdb)4]·CH3CH2OH,{H2bdb=4,4'-双(4",4",4"-三氟代-1",3"-二氧代丁基)邻三联苯}.该配合物在紫外和近紫外光激发下发出铕离子特征红光.配合物中三价铕离子的5D0激发态寿命为704μs,寿命曲线很好地和单指数衰减拟合曲线相吻合.监控614nm的红光发射,激发光谱位于250～420nm范围.在395nm处具有很强的激发强度,该配合物能够被395nm发射的InGaN芯片发出的近紫外光激发而发红光.变温光致发光测定表明,该配合物的温度淬灭效应很小.当温度升高到200℃,依然发射出很强的红光.配合物热稳定性达到260℃.发光性质和热稳定性满足制备LED器件的要求.将该配合物与395nm发射的InGaN芯片组合制备了红色发光二极管,当配合物和硅树脂的质量比为1:20,工作电流为20mA时,红色发光二极管的色坐标为x=0.61,y=0.31,发光效率为3.64lm/W.将该配合物与发蓝绿光的二-2-(2'-羟基苯基)苯并噻唑锌混合涂布在395nm发射的InGaN芯片上制备成了白光发光二极管,合适的质量比为铕配合物:锌配合物:硅树脂=1:1:25.工作电流为20mA时,色坐标x=0.32,y=0.32;色温Tc=6026K;显色指数Ra=81;发光效率为1.26lm/W.结果表明,该配合物是制备半导体高显色指数白光LED的一种红光材料.     

可见光响应的荧光增白剂基多功能光引发体系

将4,4'-双(苯并噁唑-2-基)二苯乙烯(BBS)、 7-二乙氨基-4-甲基香豆素(C 1)、 双-(三嗪基氨基)-二苯乙烯二磺酸(CBUS 450)、 4,4'-双(2-磺酸苯乙烯基钠)联苯(CBS X)和1,4-双(2-苯并噁唑基)萘(OB 7)等5种含有不同荧光发射基团的商用荧光增白剂分别与二苯基碘鎓六氟磷酸盐(IOD)组成二元光引发体系, 再与N-乙烯基咔唑(或叔胺)组成三元光引发体系, 在可见光发光二极管(LED)光源辐照下, 通过自由基聚合反应制备丙烯酸酯树脂, 同时通过阳离子/自由基同步聚合反应制备互穿网络聚合物. 利用紫外-可见分光计荧光分光计、 电子自旋共振波谱仪、 傅里叶变换红外光谱仪、 扫描电子显微镜和原子力显微镜对荧光增白剂和互穿网络聚合物进行了表征. 研究结果表明, 荧光增白剂在可见光LED的照射下可作为具有高效能的多功能光引发剂. 其中苯并噁唑-萘衍生物(OB 7)、 三嗪茋衍生物(CBUS 450)、 二苯乙烯-联苯衍生物(CBS X)和香豆素衍生物(C 1)基二元光引发体系和三元光引发体系即使在空气中也表现出了优异的光引发能力.     

Effect of Various Colors of Light-Emitting Diodes (LEDs) on the Biomass Composition of Arthrospira platensis Cultivated in Semi-continuous Mode

In the present study, semi-continuous cultivation of Arthrospira platensis using various colors of light-emitting diodes (LEDs) as artificial lighting was performed in order to study their effects on the biomass composition of A. platensis. The lowest biomass productivity was obtained with blue LED (4.68 mg l^?1 day^?1), while the highest was obtained with pink and red LEDs (30.89 and 30.69 mg l^?1 day^?1, respectively). All biomass compound contents were affected by the different colors studied, except that of total carotenoids. The lowest phycocyanin content was observed in pink LED (8.2 %) while the maximum in blue LED (17.6?±?2.4 %). Chlorophyll content was lowest in red LED (1.04 %) and highest in blue LED (1.42 %). The highest protein content was obtained with white and green LEDs (50.1 and 49.8 %, respectively), while the lowest was obtained with blue LED (42.1 %). Carbohydrate content was contrarily affected as that of proteins. The highest carbohydrate content was obtained in blue LED (11.3 %) and the lowest under white and pink LEDs (8.8 and 8.8 %, respectively). Lipid content seems to follow the same trend as that of carbohydrates; the highest lipid content was obtained in blue LED (6.0 %), and the lowest was obtained under pink LED (3.8 %).     

A simple colorimetric device for rapid detection of Hg(2+) in water

A 'turn-on' fluorescent colorimetric device for Hg(2+) sensing was built using a dual light-emitting diode system. Fluorescence generated from a rhodamine derivative (RHD), an indicator for Hg(2+) sensing, was combined with a background red light, and the complex light was captured by a commercial charge coupled device camera or by the naked eye.     

UV light-emitting diode-induced fluorescence detection combined with online sample concentration techniques for capillary electrophoresis.

The application of an ultraviolet (UV) light-emitting diode (LED) to on-line sample concentration/fluorescence detection in capillary electrophoresis (CE) is described. The utility of a UV-LED (peak emission wavelength at 380 nm, approximately 2 mW) for fluorescence detection was demonstrated by examining both a naturally fluorescent (riboflavin) compound and a nonfluorescent compound (tryptophan), respectively. The detection limit for riboflavin was determined to be 0.2 ppm by the normal MEKC mode, which was improved to 3-7 ppb when dynamic pH-junction technique was applied. On the other hand, the detection limit of the tryptophan derivative was determined to be 1.5 ppm using the MEKC mode, which was improved to 3 ppb when the sweeping-MEKC mode was applied. In an analysis of an actual sample, the concentrations of riboflavin in beer, and tryptophan in urine and milk samples were determined, respectively.