聚硅烷导电性能及氧化掺杂

介绍了聚硅烷导电材料的国内外研究进展 ,侧重阐述了聚硅烷的中性半导体行为及其独特的σ电子的离域性 ;并简单介绍了提高聚硅烷导电性能的不同掺杂手段 ,着重叙述了聚硅烷氧化掺杂导电的机理及影响其掺杂功效的几个重要因素 ,同时对该领域今后的发展方向作出展望     

聚硅烷改性含硅芳炔树脂的耐热性能研究

含硅芳炔树脂具有优异的耐高温性能,在高温下可形成C/SiC有机无机杂化材料,用聚硅烷对含硅芳炔树脂进行改性以提高其含硅量。采用示差扫描量热(DSC)、红外光谱(FT-IR)分析了改性含硅芳炔树脂的固化行为,采用TGA考察了改性含硅芳炔树脂固化产物及其烧结物的热稳定性能,并用XRD对烧结物进行了分析。研究表明,改性后的含硅芳炔树脂黏度降低、硅含量提高;固化物和烧结物在1200℃下空气中的残留率均提高了40%以上;固化物经1450℃烧结后形成了β-SiC,含聚硅烷30%的改性树脂烧结物中SiC含量达到41%。     

中氮茚接枝的新型聚硅烷的合成及其荧光性能研究

首次报道中氮茚接枝的二甲基二苯基聚硅烷PMPSi-c的合成及其荧光性能研究.结果表明经过中氮茚接枝,聚硅烷荧光强度明显增强,且能发射强烈的蓝色荧光,有望用作蓝光区的荧光材料.     

Synthesis and characterization of amphiphilic star-shaped copolymers based on β-cyclodextrin for micelles drug delivery

Purpose: A series of β-CD amphiphilic star-shaped copolymers with exceptional characteristics were synthesized and their potential as carriers for micelles drug delivery was investigated.

Methods: A series of amphiphilic copolymers based on β-CD were synthesized by introducing poly (acrylic acid)-co-poly(methyl methacrylate)-poly (vinyl pyrrolidone) or poly (acrylic acid)-co-poly(methyl methacrylate)-co-poly(monoacylated-β-CD)-poly (vinyl pyrrolidone) blocks to the primary hydroxyl group positions of β-CD. The micellization behavior of the copolymers, the synthesis conditions, characteristics, drug release in vitro and tissue distribution of vinpocetine (VP) micelles in vivo were investigated.

Results: Around 60 types of β-CD amphiphilic star-shaped copolymers were successfully synthesized and the critical micelle concentration ranged from 9.80?×?10^?4 to 5.24?×?10^?2g/L. The particle size, drug loading and entrapment efficiency of VP-loaded β-CD-P₄ micelles prepared with optimal formulation were about 65?nm, 21.44?±?0.14%, and 49.05?±?0.36%, respectively. The particles had good sphericity. The cumulative release rates at 72?h of VP-loaded β-CD-P₄ micelles in pH 1.0, pH 4.5, pH 6.5, or pH 7.4 media were 93%, 69%, 49%, and 43%, respectively. And, the lung targeting efficiency of VP-loaded β-CD-P₄ micelles was 8.98 times higher than that of VP injection.

Conclusion: The VP-loaded β-CD-P₄ micelles exhibited controlled-release property, pH-induced feature and lung targeting capacity compared with VP injection, suggesting that the β-CD-P₄ copolymers are an excellent candidate for micelles drug delivery.     

Enhanced optical properties of heterostructured ZnO/CeO2 nanocomposite fabricated by one-pot hydrothermal method: Fluorescence and ultraviolet absorption and visible light transparency

Many researchers investigated the properties of either discrete metal oxide CeO₂ or ZnO materials. However, less attention has been paid to the various nanostructure and performances of CeO₂ and ZnO nanocomposite up to now. In this paper, a facile and low cost one-pot hydrothermal synthesis method has been adopted to obtained directly precursors of CeCO₃OH and Zn₅(CO₃)₂(OH)₆ with different Ce atom molar ratios to Zn, which are transformed into their corresponding metal oxide to form the ZnO/CeO₂ heterostructure nanocomposites (HSNCs) by pyrolysis. The heterostructure is composed of ZnO and CeO₂ monocrystals, simultaneously, CeO₂ monocrystals are well dispersed on the surface of ZnO monocrystal for cosmetics. Bing dependent on the analysis results of XRD and TEM for the obtained precursors before and after pyrolysis, the formation mechanism of HSNCs was proposed. To the best of our knowledge, the paper first reported heterostructured ZnO/CeO₂ nanocomposite grown in one-pot mixed aqueous solution of cerium nitrate, zinc acetate and urea without other extra surfactant. Additionally, the influence of various Ce/Zn molar ratios on the heterostructure, fluorescence emission and UV–visible absorption properties of HSNCs was investigated in detail. ZnO/CeO₂ HSNCs display higher fluorescence emission with the increasing Ce/Zn molar ratio. Meanwhile, the larger Ce/Zn molar ratio of ZnO/CeO₂ HSNCs, the stronger transparency in the visible light region and the weaker UV absorption. The results are due to the fact that the band gap of ZnO/CeO₂ HSNCs will decrease from 3.25 to 3.08 eV when Ce/Zn atom molar ratio is increased from 0 to 0.08. By the comprehensive analysis on the optical performances of HSNCs with the different Ce/Zn atom molar ratios, ZnO/CeO₂-0.04 HSNCs could become UV absorber materials and transparent material in the visible region. ZnO/CeO₂-0.04 HSNCs with the UV-filtering and Vis-transparent properties is appropriate for personal-care cosmetics.     

Weak anchoring of nematic liquid crystals on photo-induced surface relief gratings of organic polysilane

Surface relief gratings on organic polysilane thin films are fabricated by holographic exposure of ultra-violet light, and Au gratings are subsequently prepared on polysilane gratings by vapor deposition of Au. The anchoring energies of 4-pentyl-4′-cyanobiphenyl (5CB) nematic liquid crystal on the fabricated gratings are determined with a saturation voltage method. The anchoring energies of Au gratings are weaker than those of organic polysilane gratings because of suppression of π–π interaction between the liquid crystal and the alignment layer. The polar anchoring energies of Au gratings are also weaker than those reported in literature.     

Synthesis and optical properties of photochromic perinaphthothioindigo

(1,2-naphtho)(1,8-naphtho)thioindigo (PNT) has been synthesized following a simple Friedel–Crafts route and its photochemical properties in toluene and polymethylmethacrylate (PMMA) have been characterized. PNT is a photochromic molecule capable of reversible photoisomerization between a yellow form (cis-PNT, λ_max = 484 nm) and a purple form (trans-PNT, λ_max = 595 nm). The stable purple form converts to the yellow form with a trans-PNT to cis-PNT conversion quantum yield of 0.027 in toluene and 0.062 in PMMA. The unstable yellow form exhibits a cis-PNT to trans-PNT quantum efficiency of conversion of 0.27–0.85 in toluene and 0.17–0.68 PMMA, with highest conversion efficiency occurring in the vicinity of its λ_max of 484 nm. trans-PNT has a strong fluorescence quantum yield, 0.14 (toluene) and 0.16 (PMMA). For samples prepared photochemically in the cis-PNT form, slow thermal relaxation to the trans form occurs in the dark, with a half life of about 17 h in toluene (25 °C) and even slower, 168 h, in PMMA. The property of photoswitching between fluorescent and non-fluorescent forms makes this material a candidate for many applications in imaging and data storage.     

支链化结构高分子乳化剂的合成机理和应用

针对聚异丁烯顺丁烯二酸酐（PIBSA）和醇胺类产品为原料氯化催化合成的支链化结构的新型高分子乳化剂（以下简称氯化法高分子乳化剂）,进行了合成机理的研究、谱图分析和实验室储存性能的测试。该乳化剂制备的基质性能良好,添加量(质量分数）分别为1.5%和1.2%时,经过9个高低温循环,和进口高分子乳化剂添加量1.5%（质量分数）生产的基质析晶程度无差别。3组工业试验结果表明,氯化法高分子乳化剂（质量分数1.2%）生产的乳胶基质,初始爆速达3 787 m/s以上,与进口高分子乳化剂生产的乳胶基质性能相当;在矿山颠簸500 km和储存30 d的条件下,氯化法高分子乳化剂制备的乳胶基质性能衰减最小。因此,氯化法高分子乳化剂应用在现场混装乳化炸药中,可以降低乳化剂的添加量,从而达到降低成本的目的,也可以替代国外进口的高分子乳化剂,具有良好的爆破效果和储存性能。     

Synthesis and luminescence properties for europium oxide nanotubes

A novel high temperature sensitive fluorescent nanocomposite has been successfully synthesized by an economic hydrothermal method using carbon nanotubes (CNTs), europium oxide, and sodium dodecyl benzene sulfonate (SDBS). To our great interest, the nanocomposites show high temperature sensitivity after calcinations at various temperatures, suggesting a synergetic effect of CNTs and europium oxide which leads to ultrahigh fluorescence intensity of europium oxide nanotubes. When the novel high temperature sensitive fluorescent nanocomposites were calcined beyond 620 °C for 4 h, the obtained nanocomposites have a strong emission peak at around 540 and 580 nm, due to the ⁵D₀ → ⁷F_j (j = 0, 1) forced electric dipole transition of Eu³⁺ ions. In turn, the emission spectra showed a slight blue shift. The intensity of this photoluminescence (PL) band is remarkably temperature-dependent and promotes strongly beyond 620 °C. This novel feature is attributed to the thermally activated carrier transfer process from nanocrystals and charged intrinsic defects states to Eu³⁺ energy levels. The novel high temperature sensitive fluorescent nanocomposite has potential applications in high temperature warning materials, sensors and field emission displays. It is also interesting to discover that CNTs have the effect of fluorescence quenching.     

碱溶性光敏预聚物的合成与光固化性能研究

以三苯基膦作催化剂,苯酐(PA)与丙烯酸羟乙酯(HEA)反应,合成了碱溶性光敏预聚物(PA-HEA)。通过对反应体系酸值的测定,研究了反应时间、配比、催化剂用量及投料方式对预聚物转化率的影响;通过将光引发剂加入预聚物,经紫外光固化后,考察了固化膜的耐酸性、碱液剥膜、热稳定性等性能。结果表明,在反应时间为3h,HEA与PA配比1∶0.75,催化剂含量1%(质量分数)时,转化率较高;固化膜能在10%盐酸中耐酸30min以上,且在1%NaOH溶液中2min内可完全脱膜,在32.6～137℃有较好的热稳定性。     

Magnetic and optical properties of multiferroic bismuth ferrite nanoparticles by tartaric acid-assisted sol-gel strategy

Pure BiFeO₃ nanoparticles have been successfully synthesized through the tartaric acid-assisted sol-gel method at relatively low temperature. The as-prepared nanoparticles were characterized by a variety of techniques. The success in preparing pure BiFeO₃ may be attributed to the formation of heterometallic polynuclear complexes in the tartaric acid system. The ferroelectric phase transition (T_C = 851 °C) was determined, revealing the ferroelectric nature of the as-prepared BiFeO₃ nanoparticles. The result of magnetic measurement indicates the weak ferromagnetic order of BiFeO₃ nanoparticles at room temperature, which may be ascribed to the size confinement effect. The observed strong absorption in the UV region will enable BiFeO₃ nanoparticles to be potentially used as promising photocatalytic decomposition material.     

富勒烯、酞菁化学修饰聚环氧丙基咔唑的合成及其光电导性能

利用傅氏烷基化反应，合成了富勒烯C60和酞菁铜（CuPC）共同化学修饰的聚环氧丙基咔唑（PEPC）。研究结果表明，C60和酞菁铜接枝在PEPC侧链的咔唑环上。UV－Vis吸收光谱测试结果表明，C60－CuPc－PEPC在紫外和可见光区都有吸收。C60－CuPc－PEPC比CuPc-PEPC笔PEPC具有更好的光电导性能。这种UV－Vis吸收和光电导性能的改善主要是由于C60、CuPc与PEPC的相互作用。     

Synthesis and photocuring UV-curable/alkali-soluble properties of acrylic resin

以三苯基膦作催化剂,苯酐（PA）与丙烯酸羟乙酯（HEA）反应,合成了碱溶性光敏预聚物（PA-HEA）。通过对反应体系酸值的测定,研究了反应时间、配比、催化剂用量及投料方式对预聚物转化率的影响;通过将光引发剂加入预聚物,经紫外光固化后,考察了固化膜的耐酸性、碱液剥膜、热稳定性等性能。结果表明,在反应时间为3h,HEA与PA配比1∶0.75,催化剂含量1%（质量分数）时,转化率较高;固化膜能在10%盐酸中耐酸30min以上,且在1%NaOH溶液中2min内可完全脱膜,在32.6～137℃有较好的热稳定性。     

Thermal and optical properties of poly(methyl methacrylate)/calcium carbonate nanocomposite

The study deals with thermal and optical properties of poly(methyl methacrylate) (PMMA) containing 2wt% calcium carbonate (CaCO₃) nanofiller. It was found that the thermal conductivity increases with increasing temperatures, due to thermal activation of the phonons in the PMMA/CaCO₃ nanocomposite. This enhancement in the thermal conduction is mainly attributed to the heat transferred by lattice vibrations as major contributors and electrons as minor contributors during thermal conduction. The optical properties were investigated as a function of wavelength and photon energy of UV radiation. The optical results obtained were analysed in terms of absorption formula for noncrystalline materials. It was found that the measured optical energy gap for the pure PMMA is greater than the PMMA/CaCO₃ nanocomposite. The width of the energy tails of the localised states was calculated. Adding CaCO₃ nanofiller into PMMA matrix may cause the localised states of different colour centres to overlap and extend in the mobility gap. This overlap may give an evidence for decreasing energy gap when adding CaCO₃ nanofiller in the polymer matrix.     

Synthesis and investigation of optical properties of ZnS nanostructures

Structural characterizations of wurtzite zinc sulfide (ZnS) nanostructures synthesized by vapour–liquid–solid technique (VLS) were carried out by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. Spectral dependence of photoluminescence (PL) was also carried out for optical characterization. PL results indicate that the bandgap energy of bulk ZnS which is 3·68 eV at room temperature changes from 3·7 eV to 3·72 eV depending on the size of the structures. We also supported these results by calculating the bandgap energies theoretically with using the infinite potential well approximation for 1D structures.     

金/银合金纳米颗粒的制备及光学吸收特性

以柠檬酸盐为还原剂,通过共还原氯金酸和硝酸银的混合溶液制备出Au／Ag合金纳米颗粒,用透射电子显微镜（TEM）对颗粒的形貌和尺寸进行了表征。300-800nm范围的吸收光谱研究发现,Au／Ag合金纳米颗粒具有单峰等离子体吸收特征,且随着反应液中氯化金和硝酸银的摩尔比的减少,吸收峰将产生蓝移。实验结果表明,Au-Ag合金纳米颗粒的光学吸收特性具有组分可裁剪性,使其在纳米尺度的光学领域具有潜在的应用价值。     

Fabrication of Ag and Cu nanowires by a solid-state ionic method and investigation of their third-order nonlinear optical properties

Ag and Cu nanowires were separately fabricated in a direct current electric field using a solid-state ionic method, and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Their optical nonlinearities induced by 8 ns laser pulses from a frequency-doubled, Nd:YAG laser at 532 nm, were investigated using the Z-scan technique. Experimental results indicate the metal nanowires have obvious positive refractive nonlinearities and reverse saturated absorption behaviors. The self-focusing behaviors of Ag and Cu nanowires can be attributed to Kerr-induced self-focusing of laser radiation, the nonlinear refractive indexes of Ag and Cu nanowires are n₂ = 1.7 × 10^− 11 esu and n₂ = 2.4 × 10^− 11 esu respectively, and the two-photon process of Ag and the one-photon process of Cu are responsible for the difference between Ag and Cu nanowires suspended in de-ionized water in nanosecond nonlinear absorptions.     

Polymorphism of Phosphine‐Protected Gold Nanoclusters: Synthesis and Characterization of a New 22‐Gold‐Atom Cluster

A new Au₂₂ nanocluster, protected by bis(2‐diphenyl‐phosphino)ethyl ether (dppee or C₂₈H₂₈OP₂) ligand, has been synthsized and purified with high yield. Electrospray mass spectrometry shows that the new cluster has a formula of Au₂₂(dppee)₇, containing 22 gold atoms and seven dppee ligands. The cluster is found to be stable as a solid, but metastable in solution. The new cluster has been characterized by UV‐Vis‐NIR absorption spectroscopy, collision‐induced dissociation, and ³¹P‐NMR. The properties of the new cluster have been compared with the previous Au₂₂(dppo)₆ nanocluster (dppo = 1,8‐bis(diphenyl‐phosphino)octane or C₃₂H₃₆P₂), which contains two fused Au₁₁ units. All the experimental data indicate that the new Au₂₂(dppee)₇ cluster is different from the previously known Au₂₂(dppo)₆ cluster and represents a new Au₂₂ core, which contains most likely one Au₁₁ motif with several Au₂(dppee) or Au(dppee) units. The Au₂₂(dppee)₇ cluster provides a new example of the ligand effects on the nuclearity and structural polymorphism of phosphine‐protected atom‐precise gold nanoclusters.