光聚合法对聚异丙基丙烯酰胺纳米凝胶粒径及形状的控制

纳米凝胶粒径和形貌的控制一直是纳米凝胶领域的研究热点.本研究利用光聚合的方法,无需其他有机添加剂,合成出5～100 nm范围的聚酰胺凝胶.其粒径分布范围可控制在10 nm以内.通过SEM对纳米凝胶形貌进行了表征.从结果看,可在纳米尺度上对凝胶的形状进行控制,并合成出树枝状、球状、核壳结构的纳米凝胶.这些结果未在文献中报道过.     

光聚合法对聚异丙基丙烯酰胺纳米凝胶粒径及形状的控制

纳米凝胶粒径和形貌的控制一直是纳米凝胶领域的研究热点。本研究利用光聚合的方法，无需其他有机添加剂，合成出5～100nm范围的聚酰胺凝胶。其粒径分布范围可控制在10nm以内。通过SEM对纳米凝胶形貌进行了表征。从结果看，可在纳米尺度上对凝胶的形状进行控制，并合成出树枝状、球状、核壳结构的纳米凝胶。这些结果未在文献中报道过。     

聚丙烯酰胺凝胶法制备BeO纳米粉体

聚丙烯酰胺凝胶法是一种利用三维网络结构高分子将溶液中的离子包裹形成物理阻隔,制备纳米粉体的方法。本文采该方法成功地制备了BeO纳米粉体。热重分析、X射线衍射仪和扫描电子显微镜的研究表明：煅烧温度为680℃,较传统煅烧温度下降140℃。采用聚丙烯酰胺凝胶法700℃煅烧2h制备的粉体,平均晶粒尺寸为16．5nm;升高煅烧温度,粉体粒度显著增大。900℃煅烧2h制备的粉体,平均粒径为20～30nm。     

利用动态光散射研究包覆材质对纳米茄红素胶囊粒径的影响

利用微乳化技术与复合团聚法制备了单层、双层及多层包覆的纳米茄红素胶囊,并以动态光散射法先后测量分析了包覆材质对这些纳米胶囊的粒径大小及其分布的影响。研究结果表明,以碱处理动物胶单层包覆的纳米茄红素胶囊,其在pH为6.5的磷酸盐缓冲液中会出现比较严重的聚集现象;以碱处理动物胶与k-红藻胶双层包覆的纳米茄红素胶囊,其在pH为5.5的磷酸盐缓冲液中也会出聚集现象,但比单层包覆时要小很多;而多层包覆的纳米茄红素胶囊可在pH为5.5的磷酸盐缓冲液中具有良好的分散性,且没有出现聚集现象。     

透射电镜多图像拼接法测量纳米氧化镍的颗粒粒径

本文介绍了利用透射电镜多图像拼接法测量纳米氧化镍的粒度分布.该方法通过SIS软件附带的MLA多图像拼接功能拍照得到拼接图像,经过独立测量每个照片中不少于100个纳米氧化镍颗粒的尺寸,并由此计算出颗粒平均粒径尺寸为20.6nm,该结果与X射线衍射的测量结果非常吻合.通过MIA拼接方法可大幅度提高数字CCD相机的视野范围,从而有效解决了透射电镜法测量小尺寸纳米材料粒径的采样代表性问题,为纳米材料粒径测量提供了新思路.     

有机凝胶法制备纳米氧化镍及金属镍粉

研究了具体的工艺过程,并采用SEM、CV和VSM对产物的形貌、粒径及电、磁性能进行了表征。结果表明:试验制备的纳米氧化镍和金属镍粉体均在100 nm以下,分散性良好,并显示出良好的电化学电容特性和软磁性能。纳米氧化镍在–0.8~+0.4 V电压范围内,比容量达到了76.4 F/g,而纳米镍粉的Ms为50.98 A.m2/kg,Hc为9.7 kA/m。     

溶胶-凝胶法合成纳米ZnO∶Al的表征及光学性能

以六水硝酸锌和九水硝酸铝分别作锌源和掺杂剂,使用溶胶-凝胶(Sol-Gel)法合成纳米ZnO∶Al。采用X线衍射(XRD)分析、透射电子显微(TEM)分析、X线光电子能谱(XPS)分析、光致发光光谱(PL)分析等方法对纳米ZnO∶Al进行表征。实验结果表明,Sol-Gel法合成纳米ZnO∶Al颗粒为六方纤锌矿型结构,当前驱体摩尔浓度为0.25 mol/L、热处理450℃和掺杂Al摩尔分数为3%时,样品的结晶性良好;XPS也证实Al~(3+)掺杂进入到ZnO晶体中,样品呈类球形,颗粒大小随前驱体浓度的增大而减小;对应的室温PL光谱上近紫外发射峰和弱蓝光缺陷峰强度都随浓度的增大而减小。     

电化学聚合温度对聚吡咯铝电解电容器性能的影响

采用化学聚合和电化学聚合两步法制作聚吡咯(PPy)铝电解电容器,研究了电化学聚合温度对PPy的微观形貌及聚吡咯铝电解电容器的电容和等效串联电阻Res的影响,结果表明:在10～20℃聚合所得到的聚吡咯铝电解电容器的电性能都比较理想,尤以15℃电化学聚合的为最优,其电容最大为12.6μF,Res最小为32mΩ。并且在此温度条件下制备的PPy致密性高,颗粒大小均匀。     

x光纳米光刻掩模的离子束制备法

重离子束轰击聚碳酸酯后,对样品进行陈化和紫外线照射敏化,在优化条件下蚀刻后得到纳米孔径核孔膜。利用电化学沉积技术在核孔膜中制备了最小孔径为30纳米的铜纳米线。获得的铜纳米线/聚碳酸酯可以作为x光纳米光刻的掩模。     

激光能量密度对激光诱导炽光技术测试碳烟粒径的影响

激光诱导炽光（Laser Induced Incandescence,LII）技术,由于其具有高的时间和空间分辨率,被认为是一种适合于测试碳烟浓度的技术,也可以用来测试碳烟主小球粒径。在LII 测试过程中,不同激光能量密度对测试精度影响很大,高激光能量密度具有较高的信噪比,但是对于碳烟粒径测试,为了避免升华,应尽量使用低的激光能量密度。具体在利用激光诱导炽光技术推断碳烟粒径的实验中所用的低能量密度为何值,需要结合理论模型分析和实验进行确定。首先基于LII测试过程的数学模型进行了理论分析,然后在乙烯层流扩散火焰的相同位置上,测试得到了不同激光能量密度下的碳烟主小球粒径,分析确定了测试所需的最佳激光能量密度。为进一步测试碳烟的主小球粒径奠定了基础。     

Nanopatterned Polymer Brushes for Triggered Detachment of Anchorage‐Dependent Cells

Surfaces modified with thermoresponsive poly(N‐isopropylacrylamide) (PNIPAAm) support mild and efficient harvesting of anchorage‐dependent cells. To enable cellular detachment, however, the surfaces must exhibit a narrow range of PNIPAAm thicknesses. In this work, this limitation is circumvented by introducing nanopatterns to grafted PNIPAAm brushes, eliminating the critical thickness requirement for cell‐culturing applications. Nanopatterned PNIPAAm surfaces are prepared using a combination of interferometric lithography (IL) and surface‐initiated polymerization. Above the lower critical solution temperature (LCST) of PNIPAAm (～32 °C), these surfaces support the attachment and proliferation of mammalian cells (e.g., fibroblasts and endothelial cells). Below the LCST of PNIPAAm, cells readily detach from the nanopatterned PNIPAAm surfaces without influence from the period of nanopatterns, which vary between 157 ± 9 nm to 1021 ± 17 nm. Cells selectively attach and proliferate on PNIPAAm nanopatterns as compared to thick unpatterned PNIPAAm, which is further exploited to spatially direct cellular growth to generate cellular micropatterns. Nanopatterned PNIPAAm surfaces provide a unique solution to the critical thickness issue for cell harvesting and facilitate spatial control of cellular growth on surfaces.     

Chemical Synthesis of Narrow-Sized Distributions of Cadmium Sulfide Nanoparticles for Fabrication of Poly-Phenylene-Vinylene–Cadmium Sulfide (PPV-CdS) Diodes

Cadmium sulfide (CdS) nanoparticles of three different sizes of 1.49, 2.0, and 2.1 nm were synthesized by the chemical method using thioglycerol as a capping agent. Optical absorption, wide angle x-ray scattering (WAXS), small angle x-ray scattering (SAXS), and high-resolution transmission electron microscopy (HRTEM) measurements revealed that nearly monodispersed particles of high quality could be obtained using a simple and straightforward method used in the present investigation. The nanoparticles were further used to fabricate heterojunctions with poly-phenylene-vinylene (PPV), and current-voltage characteristics were measured. A large forward current density of 21 mA cm⁻² at 1 V is obtained for samples having the smallest average particle size and 13 mA cm⁻² for the samples having the largest particle size among the samples investigated.     

反应性液晶修饰的光敏聚芳醚光取向稳定性研究

采用反应性液晶通过光聚合反应与聚芳醚光取向膜复合方法,制备了平面转换(In-plane switching,IPS)液晶显示器件,并在高温状态下对其光电显示和取向稳定性能进行了研究。结果显示,与单一聚芳醚光取向膜相比,利用复合光取向膜制备的IPS器件在高温状态下的光电显示和液晶取向稳定性能都得到了明显提高,在65℃明亮显示20h无液晶取向变化,在120℃维持2h无明显光量渗透。在线偏振紫外光下,光敏聚芳醚薄膜发生各向异性光交联反应,其交联程度最高可达67.4%。SEM分析结果发现,反应性液晶单体在UV光照射下,在聚芳醚光取向膜表面上发生了各向异性光聚合反应,沿先前光取向方向形成长度为0.4μm左右的棒状聚合物,有效限制了光取向膜中未交联的柔性基团的活动能力,进而有效增强了复合取向膜对液晶的取向稳定性。     

Compensation phenomena by ion implantation doping of an electroactive polymer,poly(para-phenylene)

We have shown that poly(para-phenylene) (PPP) can be obtained either n-type or p-type by ion implantation at low energy (E ≦ 50 keV); PPP is primarily an insulator pellet obtained from compacted powder synthetised by the Kovacic method. To compare with the chemical doping effect, we have studied the conductivity and thermopower of PPP samples after two successive ion implantations with Cs⁺ and I⁺. The experimental results show that we clearly obtain reversible doping only in the case of an initially I⁺-doped sample: the thermopower sign is changed after a Cs⁺ implantation with a fluence equal to 3 × 10¹⁴ ions cm^?2. In the other case (Cs⁺ initial implantation) we observe the change in thermopower sign at higher fluence (2 × 10¹⁶ I⁺ ions cm^?2). This last effect can be attributed to a metal transition induced by the accumulation of defects in the material because of too high implantation parameters (graphitisation).     

Photothermally Sensitive Poly(N‐isopropylacrylamide)/Graphene Oxide Nanocomposite Hydrogels as Remote Light‐Controlled Liquid Microvalves

A photothermally sensitive poly(N‐isopropylacrylamide)/graphene oxide (PNIPAM/GO) nanocomposite hydrogel can be synthesized by in situ γ‐irradiation‐assisted polymerization of an aqueous solution of N‐isopropylacrylamide monomer in the presence of graphene oxide (GO). The colors and phase‐transition temperatures of the PNIPAM/GO hydrogels change with different GO doping levels. Due to the high optical absorbance of the GO, the nanocomposite hydrogel shows excellent photothermal properties, where its phase transitions can be controlled remotely by near‐infrared (NIR) laser irradiation, and it is completely reversible via laser exposure or non‐exposure. With a higher GO loading, the NIR‐induced temperature of the nanocomposite hydrogel increases more quickly than with a lower doping level and the temperature can be tuned effectively by the irradiation time. The nanocomposite hydrogel with its excellent photothermal properties will have great applications in the biomedical field, especially as microfluidic devices; this has been demonstrated in our experiments by way of remote microvalves to control fluidic flow. Such an “easy” and “clean” synthetic procedure initiated by γ‐irradiation can be extended for the efficient synthesis of other nanocomposite materials.     

流式细胞术的一种定量修正

针对流式细胞术在细胞大小测量中的不足，提出了一种简单的解决方法。即用被染色细胞，激光照射后透过光强的不同，达到对细胞大小的实时测量。与流式细胞仪结合使用，我们能给出细胞大小的分布曲线。     

Permanent and Peripheral Embolization: Temperature‐Sensitive p(N‐Isopropylacrylamide‐co‐butyl Methylacrylate) Nanogel as a Novel Blood‐Vessel‐Embolic Material in the Interventional Therapy of Liver Tumors

Permanent and peripheral embolization is a requirement of embolic materials in the transcatheter arterial embolization of liver tumors. So far, it has been difficult to find materials that have both good flowability and high mechanical strength. In the present work, a temperature‐sensitive p(N ‐isopropylacrylamide‐co‐butyl methylacrylate) (PIB) nanogel is explored as a novel blood‐vessel‐embolic material in the interventional therapy of liver tumors. With increasing temperature, the PIB nanogel dispersion sequentially exhibits three phase states; swollen gel, flowable sol, and finally shrunken gel. Iohexol, a nonionic X‐ray contrast agent, increases the volume‐phase transition temperature of the PIB nanogel and decreases the critical gelation concentration. Angiographical and histological studies on the embolization in the liver arteries of VX2 tumor‐bearing rabbits indicate that the PIB nanogel dispersion mixed with iohexol (designated as PIB‐I‐6150) completely occludes all levels of blood vessels, including peripheral vessels. In addition, data on tumor volume, necrosis level, and the number of metastatic foci indicate that PIB‐I‐6150 has better peripheral embolization than Lipiodol. Experiments concerning cytotoxicity, hemolysis, histology, and liver function indicate that PIB‐I‐6150 has good biocompability.     

Determination of the electroaffinity and potential barrier heights at polymer/ metal interfaces of poly(4,7-benzothiophene vinylene) (PBTV)

In this paper we determine the LUMO level position of poly(4,7-benzothiophene vinylene) (PBTV), a heterocyclic poly(phenylene vinylene) (PPV) analogue, using tunnelling current measurements. We compare the energy level positions with those measured for PPV and determine their shifts. The experimental results are compared with theoretical predictions and good agreement is observed. © 1998 John Wiley & Sons, Ltd.