稀土掺杂硅铝氧烷凝胶的制备及电流变效应

采用乳液聚合的方法以α－甲基丙烯酸甲酯为单体对硅铝氧烷溶胶进行表面覆合，将所制得包裹了PMMA的高介电硅铝氧烷凝胶粉末，与硅油相充分混合是到了电流变效应非常显著的ER流体。同时，通过掺杂稀土化合物得到了一系列掺杂了稀土离子的PMMA包裹的硅铝氧烷凝胶粉末样品，测量 了在外加电场作用下该ER流体粘度随不同的样品浓度，不同的掺杂离子，温度的改变等影响，同时测量了漏电流密度，介电常等相关的物理量。讨论了乳液聚合原理，电流变效应机制。     

稀土PMMA包裹硅铝氧烷凝胶填充天然橡胶的抗疲劳作用

用聚甲基丙烯酸甲酯（PMMA）对水玻璃、硝酸铝和α－甲基丙烯酸形成的硅铝氧烷溶胶进行包裹，得到PMMA包裹的硅铝氧烷凝胶，同时在反应过程中用稀土离子进行掺杂，得到的稀土掺杂PMMA微囊粉末填充到天然橡胶之中，经力学性能分析发现杨氏模量普遍提高，抗疲劳效果显著，一万次伸张疲劳后，拉伸强度的保持率比参照样品提高两倍以上。     

稀土对硅铝氧烷凝胶电流变性能的改性及其表征

合成了镧、镨、钇、钆、铕等稀土离子掺杂的聚甲基丙烯酸甲酯(PMMA)包裹的硅铝氧烷凝胶样品，采用显微照片、FTIR，XRD，XRF，TG等方法表征了样品的特性，研究了稀土对其硅油悬浮液的电流变效应的改性作用。     

无皂乳液聚合制备硅铝氧烷/PMMA复合体系

硅铝氧烷溶胶;聚甲基丙烯酸甲酯复合体系;无皂乳液聚合制备硅铝氧烷/PMMA复合体系     

稀土掺杂PMMA包裹硅铝氧烷凝胶的ER效应

以二氧化硅微粒制备电流变液是研究者使用较多的一种方法[1] ,但由于二氧化硅的密度相对于分散相硅油来说太大 ,所以制成的电流变液稳定性较差。而用导电高分子微粒制成的电流变液则有在高电场时漏电流密度较大的问题[2 ] 。有研究者用直接聚合法在二氧化硅纳米微粒外包裹一层有机共聚物 ,生成一种微囊复合颗粒 ,可以使其相对密度减小 ,提高了电流变液的稳定性[3] 。我们以廉价水玻璃为原料制取硅铝氧烷溶胶 ,在其表面包裹聚甲基丙烯酸甲酯 (ＰＭＭＡ)后 ,得到ＰＭＭＡ包裹的硅铝氧烷凝胶具有相当的稳定性和易极化性 ,易形成较稳定的悬浮液 …     

硅倍半氧烷改性聚酰亚胺(PI/Si)复合膜性能简

通过在聚酰亚胺(PI)中分别添加笼型八氨基苯基硅倍半氧烷(OAPS)、笼型八苯基硅倍半氧烷(OPS)、梯形聚苯基硅倍半氧烷(PPSQ)和无机纳米SiO2,制备了4种含硅聚酰亚胺(PI/Si)复合膜. 对PI/Si复合膜的相容性、力学性能、热性能和阻燃性能进行了研究. 结果表明,OAPS与PI间展现出较好的相容性,PPSQ次之,而OPS,SiO2与PI的相容性较差;但相容性与复合膜的力学和热性能无明显的对应关系. SiO2可提高PI的力学性能;PI/OAPS复合膜的Tg最高;OAPS,PPSQ或SiO2的加入使PI复合膜的热稳定性稍有提高,而少量OPS的加入大大降低PI膜的热稳定性. 这类PI/Si复合膜的显著特点是能够大幅提高PI膜的极限氧指数,含硅化合物能够增加PI燃烧后残炭量,使残炭的形貌得到显著改善. PI/Si复合膜在燃烧过程中在表面形成一层白色含硅包裹层,起到隔热隔氧及保护内层有机物不被燃烧的作用. 硅倍半氧烷对炭层形貌的改善显著,展现出比SiO2更好的阻燃性能.     

硅倍半氧烷改性聚酰亚胺(PI/Si)复合膜性能

通过在聚酰亚胺(PI)中分别添加笼型八氨基苯基硅倍半氧烷(OAPS)、 笼型八苯基硅倍半氧烷(OPS)、 梯形聚苯基硅倍半氧烷(PPSQ)和无机纳米SiO₂, 制备了4种含硅聚酰亚胺(PI/Si)复合膜. 对PI/Si复合膜的相容性、 力学性能、 热性能和阻燃性能进行了研究. 结果表明, OAPS与PI间展现出较好的相容性, PPSQ次之, 而OPS, SiO₂与PI的相容性较差; 但相容性与复合膜的力学和热性能无明显的对应关系. SiO₂可提高PI的力学性能; PI/OAPS复合膜的T_g最高; OAPS, PPSQ或SiO₂的加入使PI复合膜的热稳定性稍有提高, 而少量OPS的加入大大降低PI膜的热稳定性. 这类PI/Si复合膜的显著特点是能够大幅提高PI膜的极限氧指数, 含硅化合物能够增加PI燃烧后残炭量, 使残炭的形貌得到显著改善. PI/Si复合膜在燃烧过程中在表面形成一层白色含硅包裹层, 起到隔热隔氧及保护内层有机物不被燃烧的作用. 硅倍半氧烷对炭层形貌的改善显著, 展现出比SiO₂更好的阻燃性能.     

稀土氧化物对Ni-Zn铁氧体/泡沫铝吸波性能的影响

为研究掺杂稀土氧化物对Ni-Zn铁氧体/泡沫铝材料吸波性能,在泡沫铝表面涂覆了单一 Ni-zn铁氧体(记作CFe)和掺杂质量分数为1%的稀土氧化物的Ni-Zn铁氧体复合粉(记作CFe'),利用CJB 2038-94"雷达吸波材料反射率测试方法"中的雷达截面(RCS)法对材料微波反射率进行了测量,扫描电镜(SEM)和X射线衍射仪(xRD)对吸波剂的形貌和物相进行了分析.结果表明,在12～18 GHz频段内,泡沫铝表面涂敷单一的铁氧体其吸收量为1.8 dB,加人稀土氧化物后,其吸波值由1.8 dB增至2.65 dB,在26.5～40 GHz频段内时,添加稀土氧化物后,吸收量有较大的提高,从11 dB增加到15 dB,10 dB带宽扩展近6倍.因此掺杂稀土氧化物是提高吸波材料性能的一种途径.     

多核钕-铝双金属配合物催化丁二烯聚合V.甲基铝氧烷的影响

以外添加的方式,考查了甲基铝氧烷(MAO)对多核钕-铝双金属配合物催化了二烯聚合的影响,并与烷基铝存在下的作用结果相比较.结果表明,MAO用量较低时(n(Al)/n(Nd)在5～20之间),即可较烷基铝更大程度提高稀土配合物的催化活性,获得顺式聚了二烯;MAO的链转移作用较烷基铝的低.     

^29Si,^27AIMASNMR研究不同脱铝深度稀土 超稳Y沸石中Si、Al的分布

本文应用^29Si,^27AIMASNMR和XRD技术,测量了四种不同脱铝深度的稀土超稳Y沸石的骨架硅铝比,得到了一致的结果,并研究了稀土超稳Y沸石的脱铝过程和稀土离子和Y沸石骨架铝的机理.发现稀土离子存在时,Y沸石骨架中Si、Al的分布与相同硅铝比的ＨＹ不同,在浅、中度脱铝时,主要脱除的是Si(2Al)和Si(3Al)中的铝,深度脱铝时,主要是Si(1Al)和少量Si(2Al)中的铝,而Si(3Al)几乎不变,提出稀土离子最可能是位于方钠的Si(3Al)附近,平衡三个AlO 四面体上的负电荷,起到稳定Si(3Al)结构单元的作用.其次,稀土超稳Y沸石中总的非骨架铝(N~Al)~EF,随脱铝深度的增加而增加,仅只在REUSY-38的^27AIMAS NMR谱中观察到Al^3+非骨架铝的存在.^29Si,^27AIMASNMR     

非水凝胶原位聚合法制备三异丙氧基钕/PMMA杂化材料的研究

通过三异丙氧基钕直接掺入MMA单体 ,迅速形成凝胶后进行原位聚合的方法制得三异丙氧基钕 /PMMA杂化材料 ,采用IR、TG、WAXD、DMTA、SEM等手段对其进行表征 .结果表明 ,三异丙氧基钕与MMA中的羰基因配位并导致交联形成了交联网状结构的杂化材料 .与PMMA相比 ,这种杂化材料具有优良的耐热性、耐溶剂性 ,高贮能模量 ,同时 ,该制备方法克服了稀土离子易缔合的缺点 ,获得了高稀土含量且均匀分布的三异丙氧基钕 /PMMA杂化材料     

脂肪酸铕配合物聚合物材料的合成及发光性质

以一定比例正辛酸和月桂酸为第一配体,通过皂化法合成了脂肪酸铕配合物,并溶于甲基丙烯酸甲酯（MMA）单体通过本体聚合得到了含脂肪酸铕的PMMA光致发光聚合物材料AxByEu/PMMA（其中A=正辛酸根,B=月桂酸根,x、y分别表示正辛酸和月桂酸的比例）。考察了不同的第二配体（咔唑、二甲基-联吡啶、邻菲罗啉、噻吩甲酰三氟丙酮HTTA）对脂肪酸铕聚合物发光性能的影响,选择出合适的第二配体HTTA,进而合成了A3Eu/HTTA/PMMA聚合物。通过红外光谱、紫外光谱及荧光光谱对脂肪酸铕配合物及聚合物的结构和荧光性能进行表征。结果表明：合成的脂肪酸铕配合物及其聚合物均具有很好的光致发光性能,紫外激发能发射Eu3+离子的特征红光。当HTTA的质量分数减小至0.02%时,仍能很好地促进体系的发光,且不影响聚合物本身的透明性。     

Combinatorial study of cofluorescence of rare earth organic complexes doped in the poly(methyl methacrylate) matrix

The luminescence enhancement effect of different kinds and contents of rare earth complexe (RE(DBM)3Phen, RE = Dy, La, Gd, Sm, Y; DBM = dibenzoylmethane; Phen = 1,10-phenanthroline) sensitized Eu(DBM)3Phen doped in poly(methyl methacrylate) (PMMA) matrix was investigated using the combinatorial method. The efficiency of the luminescence enhancement increases with a decrease in the weight percentage of the Eu(DBM)3Phen and an increase in the molecular weight of the PMMA in the systems. Among these sensitization ion complexes, La(DBM)3Phen shows the highest sensitization efficiency. At the optimal content of 5 wt % Eu(DBM)3Phen and 350,000 g/mol weight average molecular weight (Mw) of PMMA, the maximum sensitization efficiency of La(DBM)3Phen is approximately 20 times. We believe that the PMMA with high molecular weight enwraps the rare earth complexes and keeps the donors and acceptors close, which results in the effective intermolecular energy transfer and, consequently, the high sensitization efficiency.     

The study of preparation and luminescence of polymethyl methacrylate/rare earth composite luminescent materials

The alkaline-earth–rare-earth–aluminate systems phosphors are the new types of phosphors, which process very bright, safer, and excellent photoluminescence. Because of hydrolysis, however, the capacity of luminescent materials will fall down and the use value of luminescent materials will also be lost. Water-resistant polymers, which can form a kind of water-resistant clad on the surface of luminescent material powder, will solve this problem and the significance of its application is important. In this study, the polymethyl methacrylate (PMMA)/rare earth composite luminescent materials were prepared through grafting emulsion polymerization of methyl methacrylate onto the surface of luminescent materials. To study the structure and properties of the PMMA/rare earth composite luminescent materials, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and photoluminescent properties were measured. From the curves of FTIR and TGA, we can find that the organic parts are attached with the inorganic parts in the PMMA/rare earth composite luminescent materials. The results of luminescent decay curves show that the resistance to water of the PMMA/rare earth composite luminescent materials is much better than that of the unmodified luminescent materials because the organic parts had been grafted on the luminescent materials.     

甲基丙烯酸甲酯与稀土配合物单体的共聚合研究

稀土异丙醇盐与β 二酮、丙烯酸、１ ,１０ 邻菲罗啉或２ ,２′ 联吡啶反应,生成的稀土配合物单体与甲基丙烯酸甲酯共聚合得３２ 种稀土金属有机高分子．共聚物用元素分析、ＦＴ ＩＲ、１Ｈ ＮＭＲ、ＸＰＳ、ＵＶ、ＧＰＣ、ＤＴＡ、ＴＧ 等技术进行表征．     

本体聚合制备Sm(OPr~i)(TTA)_2/PMMA光致发光材料

合成了(异丙氧基)二(α-噻吩甲酰三氟丙酮基)钐[Sm(OPri)(TTA)2]配合物,并通过本体聚合制备Sm(OPri)(TTA)2/PMMA光致发光材料,采用IR1、H-NMR、XRD、DMTA、FS、ESEM对其进行表征.结果表明,Sm-(OPri)(TTA)2/PMMA在396 nm波长激发下在562、598、644 nm处发射很强的Sm3+离子4G5/2→6H5/2,4G5/2→6H7/2,4G5/2→6H9/2跃迁的特征荧光,其发光强度与Sm(TTA)3/PMMA相当;其储能模量E′、玻璃化温度Tg和粘流温度Tf均比PMMA有所提高;Sm(OPri)3/PMMA形成类似交联结构聚合物,而Sm(OPri)(TTA)2/PMMA为线型无定型结构聚合物.     

The Polymerization of Methyl Methacrylate with a New Nd(O—i-Pr)_3—AI(i-Bu)_3Catalyst System

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Synthesis and electrorheological response of nano-sized laponite stabilized poly(methyl methacrylate) spheres

Poly(methyl methacrylate) (PMMA) nanospheres were fabricated via surfactant-free Pickering emulsion polymerization, in which hydrophilic laponite clay was used to stabilize the emulsions of methyl methacrylate dispersed in distilled water. These synthesized PMMA nanoparticles, of which the surface is compactly wrapped by laponite clay, are observed, as confirmed by scanning electron microscopy and transmission electron microscope images. Fourier-transform infrared spectra and thermogravimetry analysis confirm the chemical composition, thermal property, and mass percent of the laponite located on the surface of PMMA particles. Finally, laponite-wrapped nano-sized PMMA spheres were adopted as an electrorheological material. By using an optical microscope, the chain-like structure was observed when an external electric field was applied. In addition, the ER performance was also examined via a rotational rheometer equipped with a high voltage generator.     

Facile fabrication of self-assembled PMMA/graphene oxide composite particles and their electroresponsive properties

Core–shell-structured poly(methyl methacrylate) (PMMA)/graphene oxide (GO) composite particles were prepared using a facile process, in which GO was adsorbed spontaneously onto a microspherical PMMA surface when hydrophobic microspheres were dispersed in deionized (DI) water stabilized by amphiphilic GO under ultrasonication. The fabricated composite was characterized by SEM, TEM, FT-IR, and thermogravimetric analysis. Results showed that the particle surface could be wrapped with GO without the need for surfactants. In addition, electrorheological behavior of the chain-forming process of the PMMA/GO composite particles was observed by optical microscopy under an applied electric field. Both shear stress and shear viscosity related to the strength of the applied electric field were measured using a rotational rheometer. The proposed Cho–Choi–Jhon model was used to describe their ER performances for the entire shear rate region. Moreover, the response of the shear stress to an imposed square voltage at a fixed shear rate was also examined.