酞菁掺杂复合体系光限幅性能的基质效应

采用Sol-gel法将四磺化酞菁镍(NiTSPc)、酞菁铅(PbPc)分别植入二氧化硅凝胶基质,制备出均匀掺杂的复合凝胶玻璃,并对光限幅性能进行了测试。研究结果表明基质的组成、结构和凝胶化过程将改变复合体系中掺杂酞菁存在的微化学环境,进而影响其激发态物理过程和由此决定的光限幅性能,表现出复合体系光限幅性能的基质效应。     

磺酸基对掺杂酞菁在溶胶-凝胶复合体系中UV/Vis吸收光谱的影响

选择、设计具有代表性无取代酞菁镍(NiPc)和周环带有4个磺酸基的四磺化酞菁镍(NiTSPc),采用溶胶-凝胶湿化学将其均匀掺入SiO₂凝胶基质,制备无机基质酞菁掺杂复合光功能材料并考察磺酸基的引入对掺杂酞菁在溶胶-凝胶复合体系中UV/Vis吸收光谱的影响。研究结果表明水溶性磺酸基的引入有助于改善酞菁的溶解性,进而实现其与溶胶-凝胶体系的稳定互溶,使酞菁均匀掺杂复合材料的制备成为可能。     

四磺化酞菁镍复合乙烯基改性二氧化硅凝胶玻璃的谱学性能研究

采用溶胶-凝胶工艺,以正硅酸乙酯(TEOS)和乙烯基三乙氧基硅烷(VTES)为硅源,以VTES中的乙烯基(CHCH₂)为有机改性剂,制备乙烯基改性二氧化硅凝胶玻璃,并在此过程中将四磺化酞菁镍(NiTSPc)掺杂其中制得复合凝胶玻璃。 所得样品分别进行红外(IR)和紫外-可见(UV-Vis)吸收光谱的表征以测试其组成、结构和NiTSPc在复合体系中的存在状态。 结果表明,VTES中的乙烯基被成功地引入SiO₂网络并实现了对其改性;复合凝胶玻璃中NiTSPc的掺杂对基质的组成、结构未产生影响;NiTSPc在乙烯基改性后的凝胶玻璃基质中得到很好的分散,基本以单体形式存在。 对所得结果进行了分析讨论。     

酞菁氯镓复合凝胶玻璃的谱学性能研究

采用溶胶-凝胶(Sol-Gel)湿化学工艺将酞菁氯镓(GaPcCl)掺入二氧化硅(SiO₂)凝胶玻璃基质,制备出均匀掺杂的GaPcCl复合凝胶玻璃,并对复合体系的红外光谱(IR)、紫外-可见吸收光谱(UV-Vis)及荧光光谱等谱学性能进行了测试。结果表明：GaPcCl的掺杂对凝胶玻璃基质的红外光谱没有产生显著影响;掺杂GaPcCl在复合体系中二聚体吸收峰的强度较其DMF溶液有所增大;掺杂GaPcCl在复合体系中荧光强度随浓度的增加远大于DMF溶液。     

四磺酸基酞菁氯化铝复合二氧化硅干凝胶的制备及光学性能研究

采用溶胶凝胶法将不同掺杂浓度的四磺酸基酞菁氯化铝(AlClPcTS)植入二氧化硅凝胶基质,制备了均匀掺杂的复合干凝胶通过对二氧化硅凝胶基质和掺杂AlClPcTS后复合干凝胶孔结构的测定和对复合体系紫外可见吸收光谱的表征,证实了AlClPcTS在基质中的成功掺杂,并发现AlClPcTS同时以单体和二聚体的形式存在于复合体系中,且AlClPcTS二聚体所占比例随着凝胶化过程的进行而增大对不同AlClPcTS掺杂浓度复合干凝胶的光限幅性能进行了测试,并讨论了掺杂浓度对复合体系光限幅性能的影响,证明复合体系的光限幅性能随掺杂浓度的提高而增强.     

四取代4-异丙苯基苯氧基酞菁铅复合凝胶玻璃的结构及光限幅性能研究

采用溶胶-凝胶(Sol-gel)湿化学工艺将四取代4-异丙苯基苯氧基酞菁铅PbPc(CP)₄掺入二氧化硅(SiO₂)凝胶玻璃基质,制备均匀掺杂的PbPc(CP)₄复合凝胶玻璃,并通过紫外-可见(UV-Vis)吸收光谱和透射电镜(TEM)图像对PbPc(CP)₄在复合凝胶玻璃中的存在状态及结构进行了表征。对PbPc(CP)₄在液相体系和固相体系中的光限幅性能分别进行了测试及对比研究。结果表明PbPc(CP)₄以团簇形式存在于复合凝胶玻璃中,并由于钢性结构固相基质的保护作用使其在复合凝胶玻璃相对于液相体系中表现出较强的光限幅特性。     

纳米碳管复合凝胶玻璃结构及谱学性能研究

用物理掺杂工艺将纳米碳管引入二氧化硅凝胶玻璃基质,成功制备了纳米碳管复合凝胶玻璃,采用X射线衍射、透射电子显微镜、紫外-可见吸收光谱、红外光谱、拉曼光谱等测试方法对其结构和谱学性能进行了表征。结果表明,通过优化掺杂工艺能够实现纳米碳管与基质的均匀复合,纳米碳管本身的结构在掺杂过程中并未发生改变。纳米碳管的引入对二氧化硅凝胶玻璃基质的紫外-可见吸收光谱和红外光谱未产生显著影响。     

酞菁锌掺杂二氧化硅凝胶基质的光谱学特征

利用溶胶凝胶技术将四磺化酞菁锌 (ZnPcS4)成功地引入到了二氧化硅凝胶基质中 ,制备了均匀掺杂的有机 /无机复合干凝胶。研究ZnPcS4分子在溶胶凝胶过程中紫外可见吸收光谱的变化规律以探索其在复合体系中的存在状态。实验表明 ,在溶胶阶段 ,随着时间的延长 ,紫外可见吸收光谱中单体的吸收峰强度增大 ,说明凝胶中酞菁单体的浓度增大 ;而形成凝胶后 ,随着时间的延长 ,紫外可见吸收光谱中单体的吸收峰强度减小 ,二聚体的吸收峰强度增大 ,说明由于体系结构和微化学环境的变化 ,酞菁分子趋向于聚合。     

酞菁锌参杂二氧化硅凝胶基质的光谱学特征

利用溶胶-凝胶技术将四磺化酞菁锌（ZnPcS4）成功地引入到了二氧化硅凝胶基质中，制备了均匀掺杂的有机/无机复合干凝胶。研究ZnPcS4分子在溶胶-凝胶过程中紫外-可见吸收光谱的变化规律以探索其在复合体系中的存在状态。实验表明，在溶胶阶段，随着时间的延长，紫外-可见吸收光谱中单体的吸收峰强度增大，说明凝胶中酞菁单体的浓度增大；而形成凝胶后，随着时间的延长，紫外-可见吸收光谱中单体的吸收峰强度减小，二聚体的吸收峰强度增大，说明由于体系结构和微化学环境的变化，酞菁分子趋向于聚合。     

PMMA/凝胶玻璃复合材料作为非线性有机分子掺杂基质的研究

对分散红1（DR1）掺杂聚甲基丙烯酸甲酯（PMMA）／凝胶玻璃复合材料的光学二阶非线笥及其热稳定性进行了研究。结果表明,PMMA／凝胶玻璃作为一种有机／无机复合材料,是介于胶玻璃和PMMA之间的一种非线性有机分子掺杂基质。随复合材料中凝胶玻璃含量增多,所制备的非线性材料的热稳定性能变好。对非线性和热稳定性的折衷考虑,获得了制备光学二阶非线笥基质材料先体PMMA和正硅酸乙酯（TEOS）的最佳混合比例。     

Controlling spin off state by gas molecules adsorption on metal-phthalocyanine molecular junctions and its possibility of gas sensor

Employing Green's function (GF) technique in combination with spin-polarized density functional theory (DFT), we study the electronic structure and magnetic properties of metal phthalocyanine (MPc) (M?=?Mn, Fe, Co, Ni, Cu, Zn) with or without four different gas molecules (NO, CO, O₂ and NO₂) adsorbing on the M atom of MPc molecule. The corresponding stable adsorption structural configurations and transport properties of MPc molecular junctions are also investigated. Our results indicate that the magnetic moment of MPc for M?=?Mn, Fe and Co can be modified by the specific gas molecule adsorption, which is mainly ascribed to competitive relation of HOMO-LUMO Gap and Hund's rules. However, for M?=?Ni, Cu and Zn, it is difficult to detect gas molecule because the interaction of M atom and these gases is most of weak van der Waals interaction. Remarkably, the spin of MPc molecule can be switched to a magnetic off-state by specific gas absorption, giving rise to a potential application on controllable spintronic devices. In addition, CO, NO, O₂ and NO₂ gas molecules can be detected selectively by measuring spin filter efficiency of these MPc molecular junctions. On the basis of our results, MPc (M?=?Mn, Fe, Co) molecular junctions can be considered as a promising nanosensor device to detect individual gas molecules.     

Interface charge transfer between metal phthalocyanine and fluorinated hexaazatrinaphthylene molecules

A typical donor/accepter (D/A) interface made of fluorinated hexaazatrinaphthylene (HATANA-F6) and metal phthalocyanine (MPc) molecules has been studied by photoelectron spectroscopy. Planar shape copper phthalocyanine (CuPc) and non-planar titanyl phthalocyanine (TiOPc) molecules show contrast behavior of D/A interface charge transfer (CT), though the electron affinity of HATANA-F6 is smaller than the ionization potential (IP) of both MPcs. While the CuPc/HATNA-F6 interface has no clue for the CT, the TiOPc/HATNA-F6 has an indication of interface CT-induced band bending. Not only the difference in IP but also molecular shape and interface geometry at D/A contact largely affect the characteristics of CT state formation.     

Water Soluble Metallo-Phthalocyanines: The Role of the Functional Groups on the Spectral and Photophysical Properties

Strategies are reported that produce symmetrical metal-free and metallo-phthalocyanine dyes, Pc and MPc, respectively, containing various numbers of water solubilizing carboxylic acid groups on their periphery that provide a dual role by also serving as functional groups to covalently link primary amine-containing targets to these dyes. In order to induce water compatibility and to minimize the degree of aggregation, the periphery of the macrocycle was decorated with various numbers of water-solubilizing groups and/or altering the identity of the metal center. The influence of the number of solubilizing groups and metal center on the spectral and photophysical properties were evaluated. MPc dyes containing 4, 8, or 16 carboxylic acid groups exhibited similar absorption and emission maxima (677 and 686 nm, respectively) with the molar absorptivity of the Q-band ∼10⁵ M⁻¹ cm⁻¹. Results indicated that the fluorescence lifetimes and quantum yields varied as a function of the metal center; the degree of carboxylation did not significantly alter these properties in DMSO, but did mediate the solubility and aggregation states when placed in aqueous solvents. The water solubilizing groups could also serve as labeling moieties for targets bearing primary amines. Results showed that the conjugate, produced by covalently linking an MPc to streptavidin through one of its carboxylate groups, generated a red-shift in the emission maximum with a fluorescence lifetime shorter than that of the native MPc dye.     

Mechanical properties of flat braided composite with flexible interphase

Textile composites have been used extensively as industrial materials because of the excellent mechanical properties resulting from the continuously oriented fiber bundle. In a study of the mechanical properties, it is important to consider the fiber/matrix interface property as for other composite materials. In a recent study, the fiber/matrix interface is regarded as an interphase that has its own material constants and thickness; consequently, the mechanical properties of a composite can be controlled by specifically designing the interphase. In this study, we applied this concept to braided composites with flexible resin as interphase for the purpose of designing the interphase. In a static tensile test, though there were no improvements in Noncut specimens (normal braided composites), but a Cut specimen (each side of the Noncut specimen was cut) with flexible interphase was improved in fracture load and displacement. The observation of the specimen edge was carried out and it was confirmed that the progress of debonding at the fiber bundle intersection was interrupted by a flexible interphase, and a matrix crack did not occur in the Cut specimen with flexible interphase. In a fiber bundle pull-out test, it was confirmed that debonding progressed not into the fiber/resin interface but into the flexible interphase in the specimen with flexible interphase, and the interfacial property at the fiber bundle intersection was improved.     

Influence of the central metal atom on the nonlinear optical properties of MPcs solutions and thin films

Third order nonlinear optical susceptibility (χ^〈3〉) of metallophthalocyanines (MPcs, where M = Co, Cu, Zn, Mg) thin films and solutions was investigated by standard backward degenerate four wave mixing (DFWM) method at 532 nm. Third harmonic generation (THG) measurement at 1064 nm performed on MPcs thin films is also discussed. MPcs thin films were grown by conventional thermal evaporation in high vacuum and solution were dissolved in tetrahydrofuran (THF), in which the studied materials are soluble. In the case of microscopic nonlinearity, we calculated the second order hyperpolarizability (γ) for MPcs solutions. We found that the χ^〈3〉 and the γ values are affected by the nature of the central metal atom. We also found that the value is larger than that measured via THG experiment. The variation in χ^〈3〉 values occurs due to the different resonance contributions.     

石墨烯/铝基复合材料在纳米压痕过程中位错与石墨烯相互作用机制的模拟研究

石墨烯因其优异的力学性能已成为增强金属基复合材料的理想增强体.然而,目前对石墨烯/金属基复合材料在纳米压痕过程中嵌入石墨烯与位错之间的相互作用仍不清晰.本文采用分子动力学模拟方法,对90°,45°和0°位向的石墨烯/铝基复合材料进行了纳米压痕模拟,研究了压痕加载和卸载过程中石墨烯/铝基复合材料的位错形核及演化,以获取不同位向的石墨烯与位错的相互作用机制,并分析其对塑性区的影响.研究发现,石墨烯可以有效阻碍位错运动,并且石墨烯会沿着位错滑移方向发生弹性变形.在纳米压痕过程中,位错与不同位向石墨烯之间的相互作用差异导致塑性区的变化趋势不同.研究结果表明,在石墨烯/铝基复合材料中,位向不同的石墨烯对位错阻碍强度和方式不同,且石墨烯位向为45°的复合材料的硬度高于其他模型.此外,石墨烯/铝基复合材料的位错线总长度的演化规律与石墨烯位向紧密相关.本文研究可为设计和制备高性能石墨烯/金属基复合材料提供一定的理论指导.     

Correlation between morphology and transport properties of composite films: Charge transport in composites

Metal/dielectric composite films consisting of metal objects located in dielectric matrix are investigated by computer simulation. The complete computer experiment is devoted to the study of correlation between structural properties and electrical characteristics of composite films. In the present analysis transport properties of films are calculated near the metal-dielectric transition when the basic mechanism of charge transport is the tunnel effect. The conductivity of composite film is disseminated into individual percolation paths influenced by object arrangements in the composite film.     

Magnetic nanofibers with core (Fe3O4 nanoparticle suspension)/sheath (poly ethylene terephthalate) structure fabricated by coaxial electrospinning

One-dimensional magnetic nanostructures have recently attracted much attention because of their intriguing properties that are not realized by their bulk or particle form. These nanostructures are potentially useful for the application to ultrahigh-density data storages, sensors and bulletproof vest. The magnetic particles in magnetic nanofibers of blend types cannot fully align along the external magnetic field because magnetic particles are arrested in solid polymer matrix. To improve the mobility of magnetic particles, we used magneto-rheological fluid (MRF), which has the good mobility and dispersibility. Superparamagnetic core/sheath composite nanofibers were obtained with MRF and poly (ethylene terephthalate) (PET) solution via a coaxial electrospinning technique. Coaxial electrospinning is suited for fabricating core/sheath nanofibers encapsulating MRF materials within a polymer sheath. The magnetic nanoparticles in MRF were dispersed within core part of the nanofibers. The core/sheath magnetic composite nanofibers exhibited superparamagnetic behavior at room temperature and the magnetic nanoparticles in MRF well responded to an applied magnetic field. Also, the mechanical properties of the nanofiber were improved in the magnetic field. This study aimed to fabricate core/sheath magnetic composite nanofibers using coaxial electrospinning and characterize the magnetic as well as mechanical properties of composite nanofibers.     

Interfaces in metal matrix composites

The interface region in a given composite has a great deal of importance in determining the ultimate properties of the composite. An interface is, by definition, a bidimensional region through which there occurs a discontinuity in one or more material parameters. In practice, there is always some volume associated with the interface region over which a gradual transition in material parameter(s) occurs. The importance of the interface region in composites stems from two main reasons: (i) the interface occupies a very large area in composites, and (ii) in general, the reinforcement and the metal matrix will form a system that is not in thermodynamic equilibrium. One can discuss the interface in a composite at various levels. An optimum one should be neither so simple that it covers only a few special cases nor so complex that it is not useful in designing composites from processing and applications points of view. In this paper, my objective is to give examples of interface microstructure in different metal matrix composite systems and suggest some ways of controlling the interface characteristics in order to control the properties of the composite. I shall give examples of the interface microstructure in different metal matrix composites (particle and fiber reinforced as well as laminates) and discuss some of the important implications on various aspects of metal matrix composites, from the processing stage to ultimate performance of the composite.     

Predicting Interfacial Strengthening Behaviour of Particulate-Reinforced MMC — A Micro-mechanistic Approach

The fracture properties of particulate-reinforced metal matrix composites (MMCs) are influenced by several factors, such as particle size, inter-particle spacing and volume fraction of the reinforcement. In addition, complex microstructural mechanisms, such as precipitation hardening induced by heat treatment processing, affect the fracture toughness of MMCs. Precipitates that are formed at the particle/matrix interface region, lead to improvement of the interfacial strength, and hence enhancement of the macroscopic strength properties of the composite material. In this paper, a micro-mechanics model, based on thermodynamics principles, is proposed to determine the fracture strength of the interface at a segregated state in MMCs. This model uses energy considerations to express the fracture toughness of the interface in terms of interfacial critical strain energy release rate and elastic modulus. The interfacial fracture toughness is further expressed as a function of the macroscopic fracture toughness and mechanical properties of the composite, using a toughening mechanism model based on crack deflection and interface cracking. Mechanical testing is also performed to obtain macroscopic data, such as the fracture strength, elastic modulus and fracture toughness of the composite, which are used as input to the model. Based on the experimental data and the analysis, the interfacial strength is determined for SiC particle-reinforced aluminium matrix composites subjected to different heat treatment processing conditions.