有机-无机复合材料光波导的制备

有机-无机复合光波导在光通信领域具有重要的应用价值,是目前的研究热点之一.采用溶胶-凝胶法分别制备了膜厚达13μm的光滑平整的PMMA膜和具有紫外感光性的膜厚为1.76μm的SiO2/ZrO2凝胶膜,研究了SiO2/ZrO2凝胶膜的感光性及紫外光照对两种薄膜折射率的影响.在此基础上,以PMMA膜为包层膜,SiO2/ZrO2凝胶膜为芯层膜,实现了光波导的包芯层复合.利用SiO2/ZrO2凝胶膜的感光性,结合紫外掩模技术,制备了条形的有机-无机复合光波导,理论分析表明该复合条形光波导能够实现入射波长为1.31μm,模数为0,1的传输.     

Fabrication of homogeneous titania/MWNT composite materials

MWNT/titania nanocomposites were prepared by an impregnation method and subsequent heat treatment at 400 °C. Precursor compounds such as titanium (IV) propoxide and titanium (IV) ethoxide were used to cover the surface of CNTs under solution conditions. Electron microscopy and X-ray diffraction techniques were carried out to characterize the as-prepared titania layers.     

One-step synthesis of mesoporous PWA/SiO2 composite materials using triblock copolymer templates

Materials in the form of highly dispersed 12-phosphotungstic acid (PWA) in mesoporous SiO₂ framework (PWA/meso-SiO₂) have been synthesized by one-step condensation method. The samples were characterized by XRD, TEM, EDX, FE-SEM, FT-IR, ³¹P MAS NMR and N₂ adsorption. The mesostructure of the materials obtained can be maintained up to the PWA loading amount of 30 wt%. The specific surface area and the pore size of the PWA/meso-SiO₂ are 600 m² g^–1 and 8.9 nm, respectively, for 30 wt% PWA loading. PWA clusters preserved their Keggin ion structure and exist in the SiO₂ framework with partial interactions between PWA and SiO₂.     

溶胶-凝胶法制备SiO_2/脂肪酸复合相变材料

采用溶胶-凝胶法制备了SiO2作为载体的脂肪酸复合有机相变材料,脂肪酸在SiO2网络空间内发生相变,在宏观上始终呈现固体粉末状.采用差示扫描量热方法、热重和红外光谱对样品进行了热力学、微相结构分析.实验结果显示出了明显的储放热行为.     

SiO2气凝胶/壳聚糖复合药物载体材料的制备和表征

采用常压干燥法制备了SiO2气凝胶,所得气凝胶为介孔结构,比表面积618.8m2/g,孔径分布5～20nm.以SiO2气凝胶为原料,通过静电吸附法制备了SiO2气凝胶/壳聚糖复合药物载体材料,采用扫描电镜(SEM)、红外光谱(FTIR)等对复合材料的结构形貌进行了分析,研究了复合材料对硫酸庆大霉素药物的担载和释放性能.结果表明,所得SiO2气凝胶/壳聚糖复合材料为多孔网络结构,其中,由450℃处理的SiO2气凝胶制得的气凝胶/壳聚糖复合材料对硫酸庆大霉素具有较好的药物担载和缓释性能.     

Fabrication of freestanding SiO2-TiO2 composite by a facile one pot method

A freestanding SiO₂–TiO₂ monolith with bicontinuous structure was prepared via a one pot sol-gel reaction. This monolith was fully characterized by using field emission scanning electron microscopy (FE-SEM), nitrogen adsorption and X-Ray diffraction (XRD). Synthesized SiO₂–TiO₂ monolith possesses great mechanical strength and interconnected macropores (throughpores, textural pores) on the micrometer scale as well as skeleton pores in nanoscale, and also possesses an anatase TiO₂ crystalline structure. Photo-catalytic breakdown of aqueous methylene blue (MB) with UV light was chosen to evaluate photocatalytic efficacy of the SiO₂–TiO₂ catalyst. These photodegradation activities indicated that MB decomposed completely within 180 min and the SiO₂-TiO₂ catalyst was readily separated from the reaction system and easily regenerated. Moreover, the photocatalytic activity of the monolithic catalyst remained unchanged after four catalytic cycles and the morphology was still intact.     

Fabrication and characterization of UV-written channel waveguides in Bi2O3-based glass

Light-induced refractive index change was investigated in an erbium-doped Bi₂O₃-based bulk glass using direct UV laser writing at 244 nm. Single mode channel waveguides were obtained with a positive refractive index change of 4 × 10⁻⁴ at 633 nm. An upper limit for propagation losses at 980 nm was estimated at 4 dB/cm. A morphological study of the exposed regions revealed that strong interactions occurred between the UV beam and the glass sample, causing physical damage and stresses in the material. To our knowledge, this is the first paper reporting the use of 244 nm laser beam to produce waveguides in a Bi₂O₃-based glass.     

Formation of electrosprayed composite nanoparticles from polyvinylpyrrolidone/mangosteen pericarp extract

Mangosteen pericarp contains a lot of α-mangostin compounds which has very high antioxidant activity. Unfortunately, it has a low solubility in aqueous solution in which for drug delivery application. This paper reports the synthesis of polyvinylpyrrolidone (PVP) nanoparticles loaded with mangosteen pericarp extract (MPE) using the ES method. PVP was trusted as a hydrophilic matrix to carry MPE. The composition of the precursor solution and solution flow rate during the ES process were varied to control the formation of PVP/MPE composite nanoparticles. PVP/MPE composite particles obtained have some wrinkles on their surface and have a geometric average diameter range of 640 to 1534 nm with a geometric standard deviation of 1.35 to 1.65. Increasing the electrical conductivity of the precursor solution resulted in a decrease of nanoparticles' average diameter. Also, the greater the flow rate, the larger the particles formed. The results agreed well with the droplet scaling relations for EHDA by Chen and Pui. Peak shifts in Fourier-transform infrared spectra of PVP/MPE composite nanoparticles indicated hydrogen bond formation between PVP and MPE. It also showed that MPE was successfully encapsulated in PVP matrix. Crystalline peaks of MPE disappear in the X-ray diffraction patterns of PVP/MPE composite nanoparticles, indicating amorphization of MPE after being electrosprayed by PVP. The differential scanning calorimetry study confirmed a hygroscopicity of PVP. The thermogram shows a broad endothermic peak from around 50 to 100 °C as a result of dehydration. In this study, the use of flow rate during the electrospraying process only affected the geometric average diameter, did not change the functional groups, thermal properties, and crystallinity of PVP/MPE particles because they came from the same precursor solution. The results here demonstrate that the ES method can be used for polymeric-nanoparticle-composite production and as an innovation in the field of drug delivery application.     

PMMA/SiO2复合气凝胶的研制

利用溶胶-凝胶技术和超临界干燥技术,制备了PMMA/SiO2复合气凝胶,并对气凝胶样品进行了表征。     

A facile synthesis of Cu(2)O/SiO(2) and Cu/SiO(2) core-shell octahedral nanocomposites

We report here a simple approach to the synthesis of Cu(2)O/SiO(2) core-shell nanocomposites in water solution. The Cu(2)O cores have a perfect octahedral structure with uniform size of about 200-300?nm. A compact SiO(2) shell 9?nm in thickness is located at the surfaces of Cu(2)O octahedra, and it is composed of fine SiO(2) nanoparticles. During the depositing of the SiO(2) particles, as we presumed, dynamic absorbing and disengaging of Na(+) at the interface of Cu(2)O octahedra and the solution made it possible for the formation of Cu-O-Si bonds between core and shell in the composites. The existence of Cu-O-Si bonds in our core-shell composite can be substantiated by peak changes at?1236 and 1080?cm(-1) in the FT-IR spectra. This is the reason why the SiO(2) shell is so compact and uniform. Moreover, these Cu(2)O/SiO(2) core-shell octahedra were further used as precursors, depending on a simple disproportionation reaction of Cu(2)O in acid, to easily achieve Cu/SiO(2) movable multicore-shell octahedral nanocomposites. In the final Cu/SiO(2) core-shell composite, the thin SiO(2) octahedral shell was held, inside of which formed several free Cu nanoparticles 50-80?nm in size. Studies on the Cu(2)O/SiO(2) core-shell octahedral composites and Cu/SiO(2) movable multicore-shell octahedral nanocomposites would be a good thing not only for fundamental research but also for applications.     

含共轭结构的ZnO/聚乙烯醇复合光催化材料的制备与性能

以ZnO和NaOH为原料,采用低温水热法合成纳米ZnO 半导体材料,并与聚乙烯醇（PVA）水溶液在超声作用下混合,通过直接煅烧制备出PVA中含共轭双键碳链结构（C）的ZnO/PVA_C复合光催化材料。采用 SEM、XRD、FTIR、Raman和UV-Vis DRS对样品进行表征。结果表明:ZnO/PVA_C复合光催化材料由结晶性能良好的纳米ZnO和具有共轭结构的聚合物组成,且界面间通过化学键Zn-O-C相连接;在模拟太阳光照射下,ZnO/PVA_C复合光催化材料对光的吸收响应可扩展到整个可见光区,并产生较高光电流。光催化性能测试结果表明,ZnO/PVA_C复合光催化材料对罗丹明B的降解催化性能（30 min降解率接近于100%）明显高于纯纳米ZnO。      

原位生成纳米SiO2/橡胶复合材料的制备及性能研究

采用原位生成技术制备了纳米SiO2/橡胶复合材料,研究了生胶的结构、反应时间、催化剂、偶联剂种类及用量对SiO2生成量及其增强橡胶硫化胶性能的影响.结果表明:生胶的结构对SiO2的生成量有较大的影响,不同生胶中生成SiO2量的顺序为NR＞IIR＞SBR＞BR＞NBR.随着反应时间的增加,SiO2的生成量增加,72h后基本达到恒定值,偶联剂的种类对SiO2生成量影响不大.当Si-69的用量为2g/100gNR、催化剂为乙二胺、反应时间为72h时,效果最佳.原位生成纳米SiO2填充橡胶硫化胶的性能优于机械共混法填充橡胶硫化胶的性能.     

Hollow waveguides with low intrinsic photoluminescence fabricated with Ta(2)O(5) and SiO(2) films

A type of integrated hollow core waveguide with low intrinsic photoluminescence fabricated with Ta(2)O(5) and SiO(2) films is demonstrated. Hollow core waveguides made with a combination of plasma-enhanced chemical vapor deposition SiO(2) and sputtered Ta(2)O(5) provide a nearly optimal structure for optofluidic biofluorescence measurements with low optical loss, high fabrication yield, and low background photoluminescence. Compared to earlier structures made using Si(3)N(4), the photoluminescence background of Ta(2)O(5) based hollow core waveguides is decreased by a factor of 10 and the signal-to-noise ratio for fluorescent nanobead detection is improved by a factor of 12.     

Fabrication and characterization of SiCw/MoSi2 composite from COSHSed powder

SiC whisker reinforced MoSi₂ composite has been successfully fabricated by hot-press sintering from “chemical oven” combustion synthesized powder. After sintering, a uniform dispersion of SiC whiskers is obtained in the MoSi₂ matrix. The Vickers hardness, flexural strength and fracture toughness of the SiC_w/MoSi₂ composite are 11.15 GPa, 457 MPa and 6.20 MPa·m^1/2, increased by 26.1%, 134.3% and 47.3% as compared to MoSi₂ matrix, respectively. At last, the mechanism of mechanical properties improvement was also proposed.     

纳米SiO2/聚丙烯酸酯复合乳液的研究

试验了四种制备纳米SiO2 /聚丙烯酸酯复合乳液的方法 ,结果表明 ,以KPS NH3·H2 O引发乳液聚合和以偶联剂处理SiO2 纳米溶胶再进行乳液聚合两种方法都可以得到稳定存在的无机纳米SiO2 /有机物复合乳液 ,其性能优于全丙乳液。而用HPC或以阳离子表面活性剂 -十六烷基三甲基溴化铵 (CTAB)处理SiO2 纳米溶胶后再进行乳液聚合两种方法 ,必须要有合适孔径的超滤膜或合适的专用阳离子单体 ,才能制得稳定的复合型的高分子乳液。     

超疏水SiO2/PS 薄膜于木材表面的构建

通过溶胶-凝胶法一步合成疏水性且具备独特形貌的二氧化硅粒子,联合聚苯乙烯以滴涂的方式于木材表面仿生合成了稳定性超疏水薄膜。经处理后的木材表面与水的静态接触角为153°,滚动角小于5°。通过扫描电子显微镜照片观察到该复合涂层拥有微米/亚微米的二维等级粗糙结构,该结构协同低表面能物质共同决定超疏水性木材的成功制得。此外,进一步研究了超疏水性木材表面的稳定性和耐久性。结果表明,该超疏水性木材于水、腐蚀性液体(酸液/碱液)、常见有机溶剂中以及一些常见条件下仍保留超疏水特性,为未来木材材料的应用领域扩展提供了有利条件。     

Chlorobenzene, chloroform, and carbon tetrachloride adsorption on undoped and metal-doped sol-gel substrates (SiO(2), Ag/SiO(2), Cu/SiO(2) and Fe/SiO(2))

Adsorption isotherms of chlorobenzene, chloroform and carbon tetrachloride vapors on undoped SiO(2), and metal-doped Ag/SiO(2), Cu/SiO(2) and Fe/SiO(2) substrates were measured in the temperature range of 398-593K. These substrates were prepared from a typical sol-gel technique in the presence of metal dopants that rendered an assortment of microporous-mesoporous solids. The relevant characteristic of these materials was the different porosities and micropore to mesopore volume ratios that were displayed; this was due to the effect that the cationic metal valence exerts on the size of the sol-gel globules that compose the porous solid. The texture of these SiO(2) materials was analyzed by X-ray diffraction (XRD), FTIR, and diverse adsorption methods. The pore-size distributions of the adsorbents confirmed the existence of mesopores and supermicropores, while ultramicropores were absent. The Freundlich adsorption model approximately fitted the chlorinated compounds adsorption data on the silica substrates by reason of a heterogeneous energy distribution of adsorption sites. The intensity of the interaction between these organic vapors and the surface of the SiO(2) samples was analyzed through evaluation of the isosteric heat of adsorption and standard adsorption energy; from these last results it was evident that the presence of metal species within the silica structure greatly affected the values of both the amounts adsorbed as well as of the isosteric heats of adsorption.     

静电纺丝法制备超疏水氟硅改性纳米SiO_2/PET共混膜

利用1H,1H,2H,2H-全氟辛基三氯硅烷对SiO_2纳米粒子进行表面改性,制备得到氟硅改性SiO_2纳米粒子(M-SiO_2),并将其与聚对苯二甲酸乙二酯(PET)共混后溶于六氟异丙醇(HFIP)溶剂中进行静电纺丝。采用接触角测量仪、扫描电镜和X射线光电子能谱研究了M-SiO_2/PET电纺膜的疏水性能、表面形貌以及化学组成。结果表明,静电纺丝法制备的M-SiO_2/PET共混电纺膜对水的接触角可高达155.2°,并且对水的滞后角仅为3.4°,即具有超疏水性能。