Self-assembled film of poly(4-carboxyphenyl)acetylene and diazoresin and its photoelectric conversion property

A novel multilayer film was assembled from water-soluble poly(4-carboxyphenyl)acetylene sodium salt (PCPA) and diazoresin (DR) in aqueous solution via electrostatic attraction. Under UV irradiation, following the decomposition of the diazonium group between the adjacent interfaces of the multilayers, the ionic bonds of the self-assembled film convert to covalent bonds and the film becomes very stable toward electrolyte aqueous solutions. Thus, the photoelectric conversion property of PCPA-containing film can be measured in a conventional three-electrode photoelectrochemical cell, and 0.5 mol/l KCl solution can be used as the supporting electrolyte. The photocurrent spectroscopy response coincides with the absorption spectrum of the irradiated self-assembled film, which indicates that the irradiated DR/PCPA film is responsible for the photocurrent generation.     

聚苯乙炔衍生物对碳纳米管的溶解作用与表面巯基官能化

设计合成了带巯基的聚苯乙炔衍生物,在产物的红外光谱上,3312和776 cm-1处炔氢特征吸收与2106 cm-1处碳碳三键的特征红外吸收消失;在产物的1H-NMR谱上,对应单体上炔氢的化学位移(δ=3.0)消失而对应共轭烯烃的化学位移(δ=6.4)出现;这些谱学特征变化证明了聚合反应的发生.巯基官能化的聚苯乙炔不仅能够发挥聚苯乙炔衍生物对碳纳米管的增溶作用,而且具有将碳纳米管表面巯基功能化的特殊性能.通过巯基与ZnO之间的强相互作用,ZnO纳米粒子被组装到巯基官能化的聚苯乙炔/碳纳米管杂化结构的外壳.本研究提供了制备新的多元复合纳米结构材料的方法.     

Optical‐limiting and nonlinear optical polyacetylenes: Synthesis of azobenzene‐containing poly(1‐alkyne)s with different spacer and tail lengths

Poly(1‐alkyne)s containing azobenzene pendant groups with different lengths of the spacer and terminal alkyloxy group {? [HC?C(CH₂)_mOCO? C₆H₄? N?N? C₆H₄? OC_pH_2p+1]_n? , where m = 1, 2, 3, or 9 and p = 4, 7, or 12} were synthesized in satisfactory yields with the [Rh(nbd)Cl]₂–Et₃N catalyst. All the polymers were soluble in common organic solvents such as CHCl₃ and tetrahydrofuran. Their structures and properties were characterized and evaluated with IR, NMR, thermogravimetric analysis, UV, and optical‐limiting and nonlinear optical analyses. All the polymers were thermally stable and decomposed at temperatures as high as ～300 °C. The optical‐limiting and nonlinear optical properties of the polymers were sensitive to their molecular structures. Polymers having shorter spacer lengths and longer terminal groups showed better performances and larger third‐order nonlinear optical susceptibility (up to 1.34 × 10^?10 esu). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2346–2357, 2006     

聚{N-[2-(4′-硫代乙酸苄酯基)丙酰基]-对氨基苯乙炔}的合成和热稳定性及有序纳米结构的形成

采用两性离子型的催化剂Rh+[η-C6H5(nbd)B-(C6H5)3]实现了含手征性中心和硫代乙酸酯基的苯乙炔单体的聚合,用红外光谱、核磁共振氢谱和紫外-可见吸收光谱表征了聚合物的结构,证实得到了预期产物.聚合物的重均分子量达到了73200,在氯仿、四氢呋喃、二氯甲烷等有机溶剂中有良好的溶解性能.聚合物热稳定性高,在氮气氛围下热分解温度为336℃,在900℃的高温下有31%的重量残留.用扫描电子显微镜观察发现,在浓度为5.0mg/mL的聚合物氯仿溶液形成的薄膜中有微米长度的棒状有序结构;由浓度为0.5mg/mL的聚合物氯仿稀溶液形成的薄膜表面有晶体析出.用透射电子显微镜观察聚合物在氯仿溶液中缓慢形成的微结构,发现当浓度高于1.0mg/mL时,聚合物在碳膜上形成铺展的薄膜,薄膜由纳米尺寸的丝带状结构取向排列而成;当浓度低于0.5mg/mL时,聚合物形成具有规则几何形态的微晶体.在聚合物热稳定性的显著提高和有序微结构的形成过程中,聚苯乙炔侧链中的手征性中心发挥了关键的作用.     

Self‐assembly and photovoltaic properties of multilayer films based on partially doped polyaniline and poly(4‐carboxyphenyl)acetylene

Multilayer self‐assembled films, consisting of partially doped polyaniline (PAN) as a polycation and water‐soluble poly(4‐carboxyphenyl)acetylene (PCPA) as a polyanion, were fabricated through electrostatic attraction. These ultrathin PCPA/PAN films were relatively stable toward aqueous electrolyte solutions and polar organic solvents, and the photoelectric conversion properties of the self‐assembled PCPA/PAN films could be measured with traditional three‐electrode cells in 0.5 M KCl aqueous solutions. With an increase in the bilayer number, the photocurrent rose, and it reached its maximum at eight bilayers. A further increase led to a current drop due to an increase in the recombination probability and weak visible‐light transmission. When neutral PAN films were used, the photocurrent increased consecutively within 15 bilayers, and this indicated that the PAN molecules in the neutral state were stronger electron donors than those in the partially doped state. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3224–3229, 2004     

Non-Aufbau Principle to Achieve High Stability Organic Luminescence Radicals

To solve the problem of stability of organic luminescence radicals, Li et al. proposed a new kind of organic luminescence radicals with non-Aufbau electronic structure by using donor-acceptor molecular structure. The stability of this kind of radicals was greatly improved and the high luminous efficiency was maintained. Using a non-Aufbau radical as the emission layer of an OLED, the maximum external efficiency of 5.3% has been achieved, which is among the highest efficiencies for pure organic near-intrared electroluminescence. This work has been published online in the Nature Materials on July 22,2019.     

A facile design for multifunctional AIEgen based on tetraaniline derivatives

Aniline oligomers have been widely used in many fields due to their excellent physicochemical properties. Owing to strong intermolecular interactions, their emission is always weakened or quenched when they are in high concentration or aggregated state, which greatly limits their fluorescent applications. Inspired by the concept of aggregation-induced emission(AIE), herein we introduced large steric groups onto the aniline oligomer to prevent the formation of packing structure. In particular, diphenyl vinyl group was bonded with oligomeric tetraaniline by a facile synthetic procedure with high yield. The obtained aniline oligomer derivative exhibited typical AIE features, which was also confirmed by density functional theoretical calculation. More importantly, this AIE oligomer was able to detect Fe~(3+) ions selectively and quantitatively. The fluorescence intensity decreased linearly along with the increment of Fe~(3+) concentration. Moreover, we demonstrated that this AIE oligomer could stain live bacteria, such as E. coli and S. aureus efficiently. All these results suggest that such a readily accessible and multifunctional tetraaniline derivative provides a new platform for the construction of fluorescent materials.     

Phase transition behavior and structure of the thermotropic liquid crystal 6‐{[(4′‐{[(undecyl)carbonyl]oxy}biphenyl‐4yl)carbonyl]oxy}‐1‐hexyne

The phase transition behaviors and corresponding structures of 6‐{[(4′‐{[(undecyl)carbonyl]oxy}biphenyl‐4yl)carbonyl]oxy}‐1‐hexyne (A4EE11) were investigated using differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and wide angle X‐ray diffraction (WAXD). In comparison with the published homologues, 5‐{[(4′‐heptoxy‐biphenyl‐4‐yl)carbonyl]oxy}‐1‐pentyne (A3EO7) which shows a monotropic smectic A (SmA) phase and a metastable monotropic smectic C (SmC) phase; 5‐{[(4′‐heptoxy‐biphenyl‐4‐yl)oxy]carbonyl}‐ 1‐pentyne (A3E'O7) that exhibits three enantiotropic stable liquid crystalline (LC) phases, SmA phase, SmC phase and smectic X (SmX) phase; 5‐{[(4′‐heptoxy‐biphenyl‐4‐yl)carbonyl]oxy}‐1‐undecyne (A9EO7) which has a monotropic SmA phase and a metastable crystal phase, A4EE11 integrates the enantiotropy, monotropy and metastability of the LC phases of those three compounds. Upon cooling from isotropic state to room temperature, in the temperature range of 62.0 to 58.5°C, A4EE11 shows an enantiotropic smectic A (SmA) phase with a layer spacing d=32.69Å. Further lowering the temperature, it enters into a metastable monotropic smectic B (SmB) phase with a longer layer spacing d=34.22Å which has a tendency towards crystallization. The metastability of the liquid crystalline phase may associate to the linkage order of the ester bridge between the mesogenic core and the flexible spacer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

混合气体组合放电清洗在HL—1装置上的实验研究

在HL-1装置上进行混合气体H_2+H_e,H_2+N_e,H_2+K_r和N_2+X_e交流(50Hz)放电锻炼孔栏(1/8石墨,7/8钼)和GH39不锈钢真空室表面,其清洗效果明显地好于通常低功率纯氢气放电清洗(TDC,GDC和ECR-DC),并能有效地降低裸金属和碳化器壁表面氢气体库贮量,有利于托卡马克放电氢再循环控制,为高密度和低q放电提供了洁净的器壁和环境。上述混合气体交流放电结合2.45GHz电子回旋共振(ECR)放电,取得了更好的清洗效果。本文对这种高效、快速清洗方法的机制作了简单分析。     

GaAs---InP heteroepitaxy and GaAs---InP MESFET fabrication by MOVPE

Lattice-mismatched heteroepitaxy has attracted considerable attention in recent years. A great interest of these systems is the possibility of integrating devices from different materials on a single substrate. 1.3 and 1.5 μm InGaAs(P)/InP laser diodes are essential for optical communication, whereas InP field effect transistor technology is less developed than that of GaAs MESFET. The performances of laser diodes are much more sensitive to a high density of disclocations, so it would be interesting to grow GaAs MESFET on InP for integration with 1.3 and 1.5 μm lasers. Due to the large difference of the thermal expansion coefficient and lattice parameter between GaAs and InP, it is very difficult to grow GaAs epilayers of high quality on it is very difficult to grow of GaAs epilayer high quality on InP substrates due to the large difference of the thermal expansion coefficient and lattice parameter between GaAs and InP. A new method, metalorganic source modulation epitaxy (MOSME), which improves the crystal quality of GaAs epilayers on InP substrates by MOVPE, has been adopted in our laboratory. The lowest full width at half maximum (FWHM) of the double crystal X-ray (DCX) diffraction spectra reaches as low as 120 arcsec for a 5 μm thick layer. Structural properties (misorientation, lattice parameters and crystal quality) of 1.0–5.0 μm thick GaAs layers grown on InP have been measured by DCX diffraction. On GaAs MESFETs grown on InP, we have measured g_m = 100 ms/mm. For these transitions, the current gain cut-off frequency (F_t) is around 12 GHz and the maximum frequency of oscillation (F_max) is higher than 30 GHz.