表面Ca2+交联对蒙脱石/聚丙烯酸(钠)吸水保水复合材料性能的影响

采用水溶液聚合法制备了蒙脱石/聚丙烯酸(钠)吸水保水复合材料,并用CaCl2溶液对其进行表面交联处理.本文研究了表面交联剂CaCl2溶液的浓度和表面交联时间对复合材料吸水、保水性能以及凝胶强度的影响.实验结果表明,Ca2+表面交联处理提高了复合材料的保水能力和凝胶强度,同时也使其吸水能力略有下降.     

聚乙烯醇和聚丙烯酸均聚物的自组装形貌

利用聚乙烯醇分子链上羟基与聚丙烯酸分子链上羧基之间的氢键相互作用,在水溶液中,根据羟基和羧基摩尔比的不同,形成了不同的组装结构。当羧基与羟基的摩尔比在10%~25%之间时,可以获得较为丰富的自组装结构。通过向溶液中添加5%~30%的甲醇,可以获得稳定的球形、棒状和网状纳米结构。动态光散射和透射电镜测试验证了聚集体的形成。通过分析聚合物链的不同氢键复合形式以及Zeta电位结果,提出了聚集体是以聚乙烯醇(PVA)/聚丙烯酸(PAA)复合链段为核,PVA链段为壳的结构。     

水溶液聚合法制备高吸水树脂及NaCl对聚合反应的加速作用

采用in-situ水溶液聚合法合成聚丙烯酸钠高吸水树脂,研究了引发剂用量、交联剂用量、反应温度和NaCl用量对树脂吸水性能的影响,得出吸水率(Q)与交联剂用量(Cc,交联剂相对单体的摩尔分率)之间存在Q=1.99Cc-0.726关系.NaCl对聚合反应具有加速作用,使反应时间大幅度缩短,但树脂的吸水率未受明显影响.     

分散剂对氧化铝悬浮液分散稳定性的影响

研究了柠檬酸、聚乙烯醇、聚丙烯酸钠和六偏磷酸钠等对Al2O3粉体表面电性能以及浆体分散稳定性的影响。结果表明,加入适量的六偏磷酸钠和聚丙烯酸钠可有效地提高浆体的分散稳定性。浆体中加入柠檬酸和聚丙烯酸钠后,氧化铝表面因特征吸附阴离子而使表面电位变负,等电点降低;而聚乙烯醇的加入,由于高分子链向体相中伸展,使剪切面向外移动更大的距离,从而使Zeta电位降低,并使等电点发生微小偏移。     

坡缕石/聚丙烯酸(钠)高吸水复合材料的溶胀行为

以水溶液聚合法制备了坡缕石/聚丙烯酸(钠) (PAANa)高吸水复合材料,对复合材料的吸水溶胀性能进行了研究,并采用FTIR对复合材料进行表征。结果表明：10 %坡缕石/PAANa复合材料吸蒸馏水和0.9 wt%盐水倍率分别达1666g/g、115g/g,较纯PAANa的724g/g、58g/g明显提高;坡缕石/PAANa复合材料具有优异的保水及反复吸水性能;坡缕石/PAANa的吸液倍率随电解质溶液离子强度的升高而降低,降低程度顺序为 Al3+>Ca2+>Na+;坡缕石/PAANa复合材料与其他6种矿物/PAANa复合材料相比,吸液性能特别是吸蒸馏水及0. 9 wt%盐水性能大幅提高。     

镍铁合金镀液中硫酸镍含量的自动电位滴定

以紫脲酸铵作指示剂的EDTA滴定法在测量镍铁合金镀液中硫酸镍含量时肉眼观察易产生误差.为此,采用自动电位滴定法测定镍铁合金镀液中的硫酸镍含量,用H<,2>O<,2>将镀液中的Fe<'2+>转化为Fe<'3+>,再用三乙醇胺掩蔽Fe<'3+>,以pCa-1型钙离子选择性电极为指示电极,以212型电极为参比电极,在Ca-E...     

TiO2/(O''+β'')-Sialon复相陶瓷的制备与表征

以纳米TiO2粉和(O'+β')-Sialon粉为原料、Yb2O3或Tb2O3为添加剂,在高纯N2气氛下采用常压烧结制备出了TiO2/(O'+β')-Sialon复相陶瓷.采用XRD对材料进行物相、晶粒度分析,采用SEM&EPMA对材料进行形貌观察和元素面分布分析.结果表明,随烧结温度的升高和恒温时间的延长,TiO2逐渐由锐钛矿相向金红石相转化,同时晶粒也逐渐长大.Tb2O3和Yb2O3分别对锐钛矿相变有显著的抑制和促进作用,通过控制烧结制度、添加剂种类及含量可得到不同TiO2相组成的TiO2/(O'+β')-Sialon.Tb2O3和Yb2O3均对TiO2晶粒生长有抑制作用,在不高于800℃的温度下烧结可得到纳米TiO2/(O'+β')-Sialon复相陶瓷.     

水溶性蒙脱土改性聚丙烯酸钠的合成及性能研究

采用水溶液插层聚合法制备水溶性蒙脱土改性聚丙烯酸钠(PNaAA)复合材料.研究了溶液pH值、有机蒙脱土及APS/SFS/AIBA引发体系用量对产物特性黏数及溶解时间的影响,并对其热稳定性、溶液性能与未改性聚丙烯酸钠进行了比较.结果表明:以自制有机蒙脱土用原位聚合方法制备的改性聚丙烯酸钠特性黏数可提高21%,并能够在其耐降解、耐剪切和耐高温能力上有较大提高.     

共价层层自组装纳滤膜的制备及性能研究

纳滤膜目前多采用界面聚合的方法制备.层层自组装是近年来发展的一种新型制膜方法,但层层自组装所制备的纳滤膜大多需要5个以上双层,制备过程繁琐,同时,以静电力结合的阴阳离子聚电解质在水中存在一定程度的解离和溶胀,结构不稳定.本文提出用静电组装与化学交联相结合的方法制备纳滤膜,增强膜的稳定性.以改性的聚丙烯腈(PAN)为基膜,以聚丙烯酸(PAA)和聚乙烯亚胺(PEI)分别为阴阳离子聚电解质,以戊二醛(GA)为交联剂,制备了共价层层自组装纳滤膜(PEI/PAA/GA)n,研究了双层数、交联剂浓度、交联时间等因素对膜性能的影响.结果表明,当制备两个双层时,(PEI/PAA/GA)_2纳滤膜对2 000 mg/L Na_2SO_4溶液中的Na_2SO_4的截留率就能达到98.1%,水通量为12.6 L/(m~2·h·MPa);对2 000 mg/L NaCl溶液中的NaCl的截留率达到82.9%,水通量为16.8 L/(m~2·h·MPa).交联后的纳滤膜有良好的耐溶胀性和长期运行稳定性.     

水热法制备板钛矿型TiO2纳米材料

0.15mol/L TiCl3的饱和NaCl水溶液加添加剂尿素(尿素/Ti3 摩尔比为1:10)用水热法170℃下反应4h在玻璃基板上制备了TiO2纳米材料(粉末和薄膜),SEM和XRD技术表征结果说明,生成的TiO2为板钛矿型晶体,TiO2粉末是由TiO2纳米棒自组装成的微米球,薄膜则是大面积纳米棒阵列形成.探索了制备TiO2纳米材料的最优条件,并讨论了反应机理.     

Ce3+掺杂聚苯胺中空微球/环氧涂层防腐蚀研究

聚苯胺作为一种新型的防腐蚀材料,在钢铁防腐蚀领域具有良好的应用前景.通过自组装法在聚(2-丙烯酰胺基-2-甲基丙磺酸)(PAMPS)水溶液中制备了聚苯胺(PANI)中空微球,将稀土Ce~(3+)掺杂到聚苯胺中空微球表面制备了一种新型的Ce~(3+)掺杂修饰的聚苯胺中空微球(PANI-Ce~(3+)).以PANI-Ce~(3+)中空微球为防腐填料添加到环氧树脂(EP)中,制备Ce~(3+)掺杂修饰的聚苯胺中空微球/环氧(PANI-Ce~(3+)/EP)防腐涂层.采用FT-IR、UV-Vis、SEM、XRD等对PANI-Ce~(3+)中空微球进行表征,通过动电位极化法、交流阻抗测试探究PANI-Ce~(3+)/EP涂层的防腐蚀性能.结果表明:PANI-Ce~(3+)/EP涂层具有较高的腐蚀电压(Ecorr=-0.414 V)和较小的腐蚀电流密度(I_(corr)=0.676×10~(-5)μA/cm~2);PANI-Ce~(3+)/EP涂层低频区阻抗模量随浸泡时间呈现先减小后增大的变化趋势,在质量分数3.5%的NaCl水溶液中经过1 680 h腐蚀后,阻抗模量保持在106.6Ω·cm~2;表面有划伤的PANI-Ce~(3+)/EP涂层在质量分数3.5%的Na Cl水溶液进行1 680 h腐蚀实验后,涂层表面不起泡,仅在划痕处有少量铁锈.PANI-Ce~(3+)/EP涂层表现出优异的耐腐蚀性能.     

One pot synthesis of monodispersed L-glutathione stabilized gold nanoparticles for the detection of Pb2+ ions

Direct mixture of Au³⁺ with glutathione (GSH), which act as both reduction agents and stabilizers, in aqueous solution gave rise to production of gold nanoparticles (Au NPs) with uniform sizes of around 21 nm. The GSH stabilizer Au NPs in solution show immediate aggregation after addition of 1 mol/L NaCl aqueous solution containing Pb²⁺ ions. The Pb²⁺-induced aggregation in Au NP solution is monitored by both colorimetric response and UV-vis spectroscopy. A rather broad linear range (from 0.1 to 30 μmol/L) and low detection limit (0.1 μmol/L) are explored for Au NP sensors used for detection of Pb²⁺ ions. Furthermore, the response of GSH-stabilized Au NPs toward Pb²⁺ ions is specific compared with other possible interferants (Hg²⁺, Mg²⁺, Zn²⁺, Ni²⁺, Cu²⁺, Co²⁺, Ca²⁺, Mn²⁺, Cd²⁺, and Ba²⁺).     

Eu2+、Dy3+、Li+共掺杂CaSi2O2N2荧光粉的发光性能

采用高温固相反应法制备了一系列白光LED用CaSi2O2N2:0.05Eu2+,xDy3+,xLi+(0≤x≤0.03)荧光粉.利用X射线衍射仪对样品的物相结构进行了分析,结果表明:Dy3+和Li+离子的掺入没有改变CaSi2O2N2:Eu2+荧光粉的主晶相.利用荧光光谱仪对样品的发光性能进行了测试,发现所有样品的激发光谱均覆盖了从近紫外到蓝光的较宽范围,400 nm激发下得到的发射光谱为宽波段的单峰,峰值位于545 nm左右,是Eu2+离子5d-4f电子跃迁引起的.Dy3+离子掺杂可以提高CaSi2O2N2:Eu2+荧光粉的发光强度,Dy3+与Li+共掺杂可进一步提高荧光粉的发光强度,当Dy3+和Li+的掺杂量为1mol%时,荧光粉的发光强度达到最大值,是单掺杂Eu2+的荧光粉发光强度的157%.     

Luminescent properties of GdAl3(BO3)4:Ln3+ (Ln3+:Eu3+, Tb3+, Dy3+) nano-phosphors

GdAl₃(BO₃)₄:Ln³⁺ (Ln³⁺:Eu³⁺, Tb³⁺, Dy³⁺) nano-phosphors were prepared by sol–gel method. The structure properties of the phosphors are characterized by XRD, and GdAl₃(BO₃)₄:Ln³⁺ nano-phosphors have average sizes around 40 nm. The doping concentrations of Eu³⁺, Tb³⁺ and Dy³⁺ ions in GdAl₃(BO₃)₄ nano-phosphors are from 1 to 9 mol% for Eu³⁺ ions, from 2 to 12 mol% for Tb³⁺ ions and from 1 to 5 mol% for Dy³⁺ ions, respectively. The luminescent properties of rare-earth ions doped GdAl₃(BO₃)₄ nano-phosphors are analyzed by the photoluminescence spectra, which prime doping concentration of Eu³⁺, Tb³⁺, and Dy³⁺ ions are at 5, 12 and 3 mol%, respectively. The energy transfers in the luminescent processes of rare-earth ions doped GdAl₃(BO₃)₄ nano-phosphors are discussed.     

On the number of V4+ ions in V2O5-MoO3 solid solutions

The nesults of magnetic and thermognavimetnic studies on V₂O₅-MoO₃ solid solutions are presented. We determine the number of V⁴⁺ ions induced by the presence of Mo⁶⁺ ones. The ratio between the number of V⁴⁺ ions and those of Mo⁶⁺ decreases by increasing the MoO₃ content. Finally, this behaviour is analysed.     

Cr~（3＋）离子掺杂对Al_2O_3粉末结构及发光性能影响

采用球磨法制备了不同浓度Cr_2O_3掺杂的Al_2O_3粉体,并在700℃、1200℃空气中退火2 h。1200℃退火后样品,除掺杂浓度为1.6%的样品中出现少量γ-Al_2O_3相外,其余样品相均为纯α-Al_2O_3。样品晶格常数随着Cr~（3＋）离子浓度的增加而增加。采用波长为579 nm的激发光源对佯品进行荧...     

Fe2+、Fe3+对CaO-Al2O3-SiO2-MgO系微晶玻璃析晶性能的影响规律

为了利用大量的含铁铝硅酸盐固体废弃物制备具有高附加值的微晶玻璃,采用DTA、XRD、SEM、EDS等手段研究了Fe2+、Fe3+对CASM系微晶玻璃析晶性能的影响.结果表明,Fe2+在微晶玻璃中与Mg2+的作用相同,取代以网络外体形式存在的Al3+,使得微晶玻璃的析晶温度逐渐下降,而对析晶能力几乎没有影响,并当Fe2+掺入量为2%时,主晶相由铝黄长石转变为镁黄长石,在7.5%时,进一步转变为透辉石.Fe3+掺量小于7.5%时,起到补充Si4+不足的作用,当大于7.5%时,部分Fe3+起到与Fe2+、Mg2+相同的作用,使得析晶温度呈先升后降的变化,在掺量为7.5%时,铝黄长石主晶相才开始转变为镁黄长石,在10%时,转变为透辉石,且析晶能力得到大幅提升.随着Fe2+和Fe3+含量增加,虽然微晶玻璃中主晶相的变化顺序相同,但Fe2+具有降低微晶玻璃析晶温度的作用,而一定量的Fe3+可作为晶核剂提高微晶玻璃的析晶能力.     

Fabrication of hybrid nanocapsules by calcium phosphate mineralization of shell cross-linked polymer micelles and nanocages

Self-assembled shell cross-linked poly(acrylic acid-b-isoprene) (PAA78-b-PI97) micelles or cross-linked PAA nanocages in aqueous solution were used as templates for the preparation of novel polymer-inorganic nanocapsules. The hybrid nanostructures were typically 50-70 nm in diameter and consisted of spherical polymer nanoparticles or nanocages enclosed within a continuous 10-20 nm thick surface layer of amorphous calcium phosphate. Nucleation of calcium phosphate specifically in association with the polymer nanoparticles was facilitated by low supersaturation levels and by sequestration of Ca2+ ions within the carboxylate-rich PAA domains prior to addition of HPO4(2-). Modifications in ionic concentrations were used to control the calcium phosphate surface layer thickness and prepare mineralized cross-linked PAA-b-PI micelles with variable shell permeability. The permeability of beta-carotene into the hydrophobic PI core of mineralized shell cross-linked PAA-b-PI micelles was reduced by approximately 50 or 100% respectively for hybrid nanostructures enclosed within 10 or 20 nm thick calcium phosphate layers. Our results suggest that calcium phosphate-polymer cross-linked nanocapsules could have potential applications as pH-responsive biocompatible hybrid nanostructures for use in applications such as drug delivery, bioimaging, and therapeutics.     

Visible light response of Ni2+ and Nb4+ doped-polycristalline TiO2 anodes

The stability of Ni²⁺ ion in n-TiO₂ anodes has been investigated. It was shown that Nb⁴⁺ ions when introduced into the TiO₂ lattice confer a n-character to the corresponding anodes and stabilize simultaneously Ni²⁺. Photocurrent measurements on TiO₂-2% NbO₂-1% NiO anodes have been carried out. A significant photocurrent resulting from the visible light excitation is observed down to 550 nm. These results are discussed on the basis of upwards shift of the 2p orbitals of the O^2? anions surrounding Ni²⁺. They are compared to those obtained for homologous Cr³⁺ anodes.     

LaMgAl11O19：Yb,Mn荧光粉中Yb^2＋与Mn^2＋的能量传递

利用共沉淀法制备了Yb和Mn离子共掺的LaMgAl11O19荧光粉。研究其室温下的发光性能。紫外光激发时观察到发光中心位于504nm的单一宽带发光峰,归因于Yb^2＋的激发态4f135d能级与基态4f14能级间的电子跃迁。同时观察到Yb和Mn共掺的LaMgAl11O19中存在Yb^2＋对Mn^2＋的传能现象,传能过程可...