Preparation and properties of fluoroalkyl end-capped oligomer/fluoresceins nanocomposites

Self-assembled fluorinated oligomeric aggregates formed by fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers, N,N-dimethylacrylamide oligomers, and acrylic acid oligomers in methanol could recognize selectively fluoresceins as guest molecules to form a new class of fluorinated aggregates/fluoresceins nanocomposites. These fluorinated fluoresceins nanocomposites were found to exhibit an extraordinarily enhanced light absorption (λ_max: ca. 440 nm) compared to that (λ_maxs: 452 and 480 nm) of the parent fluorescein in the absence of fluorinated aggregates. On the other hand, fluoroalkyl end-capped 2-carboxyethyl acrylate oligomers, which possess no aggregate characteristic in methanol solutions, could not afford such an enhanced light absorption peak under similar conditions. Not only fluorescein but also fluorescein derivatives such fluoresceinamine, carboxyfluorescein, and fluorescein isothiocyanate afforded similar enhanced narrow absorption peaks under similar conditions. Naphthofluorescein was also encapsulated into these fluorinated oligomeric aggregate cores to afford fluorinated aggregates/naphthofluorescein composites, and these fluorinated naphthofluorescein composites afforded an extremely enhanced narrow absorption peak around 520 nm.     

Adsorption of amino acids by fullerenes and fullerene nanowhiskers

Abstract

We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C₆₀) and fullerene nanowhiskers (FNWs). C₆₀ and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C₆₀ or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C₆₀ did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C₆₀ and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C₆₀ and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C₆₀ and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C₆₀. The theoretical simulations showed the bonding distance between C₆₀ and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val < Phe < Pro < Asp < Ala < Trp < Tyr < Arg < Leu. However, the simulation was not consistent with our experimental results. The adsorption of albumin (a protein) by C₆₀ showed the effect on the side chains of Try and Trp. The structure of albumin was changed a little by C₆₀. In our study Try and Tyr were hardly adsorbed by C₆₀ and FNWs. These amino acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides.     

Adsorption of amino acids by fullerenes and fullerene nanowhiskers

We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C₆₀) and fullerene nanowhiskers (FNWs). C₆₀ and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C₆₀ or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C₆₀ did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C₆₀ and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C₆₀ and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C₆₀ and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C₆₀. The theoretical simulations showed the bonding distance between C₆₀ and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val < Phe < Pro < Asp < Ala < Trp < Tyr < Arg < Leu. However, the simulation was not consistent with our experimental results. The adsorption of albumin (a protein) by C₆₀ showed the effect on the side chains of Try and Trp. The structure of albumin was changed a little by C₆₀. In our study Try and Tyr were hardly adsorbed by C₆₀ and FNWs. These amino acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides.     

Preparation and antibacterial activity of novel fluoroalkyl end-capped oligomers/silica nanocomposites-encapsulated low molecular biocides

Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [R_F-(DOBAA) _n -R_F] reacted with tetraethoxysilane (TEOS) and silica nanoparticles in the presence of low-molecular weight biocides such as hibitane, hinokitiol, and hinokioil under alkaline conditions to afford R_F-(DOBAA) _n -R_F/silica nanocomposites-encapsulated these biocides in excellent to moderate isolated yields. Fluoroalkyl end-capped N,N-dimethylacrylamide oligomer [R_F-(DMAA) _n -R_F] and acrylic acid oligomer [R_F-(ACA) _n -R_F]/silica nanocomposites-encapsulated hibitane were obtained under similar conditions. Dynamic light scattering measurements showed that the size of these fluorinated nanocomposites-encapsulated biocides thus obtained is nanometer size-controlled. Additionally, these fluorinated nanocomposites were shown to have a good dispersibility and stability in methanol and water. Of particular interest, these fluorinated nanocomposites-encapsulated biocides were found to have a good antibacterial activity against Staphylococcus aureus, and these nanocomposites were applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate).     

主链含三苯胺链段的TPA-DHPPV共聚物的合成及表征

合成了2,5-二氯甲基-1,4-二己氧基苯、1,4-二己氧基-2,5-二甲苯双(三苯基氯化季膦)和4',4-三苯胺二醛3种单体.通过聚合反应制得了聚1,4-二己氧基对苯乙炔(DH-PPV)和含三苯胺链段的PPV类共聚物(TPA-DHPPV),对聚合物进行了结构表征和性能测试.DH-PPV和TPA-DHPPV聚合物物质结构准确,在紫外光激发下能发出强的蓝绿光,荧光光谱表征说明该类聚合物均能发射较强的荧光,电致发光器件的伏安特性测试表明该类聚合物具有较低的驱动电压和较高的发光亮度,并且该类聚合物具有较高的热稳定性.     

结构型光敏二胺的合成与表征

利用微波反应合成了新型的光敏聚酰亚胺_的中间体光敏二胺(1,4-二[2-(4-氨基苯甲酰)乙烯基]苯),研究了光敏二胺的制备,并用核磁及元素、红外、紫外对其结构进行了表征,初步探讨了反应时间及反应温度的影响.     

结构型光敏聚酰亚胺的制备及研究

用均苯四甲酸二酐分别与1-(3-氨基苯基)-3-(4-氨基苯基)-2-丙烯-1-酮(光敏性二胺Ⅰ)和4,4’-二(2-间氨基苯甲酰基)乙烯基苯(光敏性二胺Ⅱ),经溶液聚合、化学亚胺化,制备了一类新型可溶性的结构型光敏聚酰亚胺。该合成方法简便,分子量容易控制,起始原料价廉易得,产品纯度与收率高。TGA,UV,GPC等研究结果表明,所制备的树脂曝光波长能与工Ⅰ业线匹配使用,具有良好的耐热性能与感光性能。     

Synthesis and investigation of boron-doped fullerene and scandium-containing fullerene

We report on the plasmachemical synthesis of fullerene derivatives containing boron and scandium. The synthesis was conducted at atmospheric pressure in a carbon-helium plasma jet generated by an RF arc.     

Synthesis and characterization of photoactive polyurethane elastomers with 2,3-dihydroxypyridine in the main chain

Photoactive polyurethane elastomers with pyridine derivatives in the polymer backbone were synthesized by chain-extending isocyanate end-capped prepolymers with 2,3-dihydroxypyridine. The isocyanate-terminated prepolymers were obtained from poly(tetramethylene oxide) glycol of molecular weight 1400 (Terathane 1400) and 1,6-hexamethylene diisocyanate. The properties of the linear heterocyclic polyurethane were compared with properties of the crosslinked heterocyclic polyurethane obtained by chain extension with various crosslinkers. Heterocyclic polyurethane elastomers were characterized using Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), dynamic mechanical analysis (DMA), contact angle measurements, and mechanical analysis. Static mechanical measurements showed greater elongation and tensile strength for polyurethanes with a lower content of heterocyclic groups in the hard segment. The static contact angles of the cast films of these polymers indicated that the nature of the hard segment influences the surface polarity. The dynamic mechanical spectra revealed that linear polymers have two transition temperatures as results from a clear phase separation caused by high-intermolecular hydrogen bonds in the regions of pyridine units and urethane groups. Polyurethane elastomer films with pyridine moieties in the main chain form a photosensitive material. If stored in laboratory conditions (light, ambient air atmosphere), the color of the films changes from white to black. These photo-induced structural changes are studied by H NMR measurements.     

Interaction between fullerenes and single-wall carbon nanotubes: the influence of fullerene size and electronic structure

A series of fullerenes and endohedral metallofullerenes peapods have been synthesized by supercritical method in high filling rate. The interaction between SWNTs and various kinds of fullerenes (C60, C70, C78, C84) and metallofullerenes (Gd@C82, Er@C82, Ho@C82, Y@C82) has been further investigated. The slight blue shift of G-band in Raman spectra with respect to pristine SWNTs was attributed to the charge transfer from SWNTs to fullerenes cage. The obvious RBM shift strongly depended on the distance between the inner wall of the SWNTs and the fullerene cage and also partly associated with the electronic structure of the fullerene. These results indicated that the interaction between fullerenes and SWNTs, which was considered to be the van de walls interaction, can be influenced by the cage size and the kind of fullerenes.     

UV-induced switching behavior of novel fluoroalkyl end-capped vinyltrimethoxysilane oligomer/titanium oxide nanocomposite between superhydrophobicity and superhydrophilicity with good oleophobicity

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer suffered the sol–gel reaction under alkaline conditions in the presence of titanium oxide nanoparticles in tetrahydrofuran to afford the corresponding fluorinated oligomer/titanium oxide nanocomposites[R_F-(VM-SiO₂)_n-R_F/TiO₂] in excellent to moderate isolated yields. These fluorinated composites thus obtained were nanometer size-controlled fine particles, and exhibited good dispersibility and stability in traditional organic solvents except for water. These fluorinated nanocomposites were applied to the surface modification of glass to exhibit not only a completely superhydrophobic characteristic (a water contact angle: 180°) with a non-wetting property against water droplets but also a good oleophobicity imparted by fluoroalkyl segments in the composites on their surface. Of particular interest, we have found that the wettability for water can be switched between superhydrophobicity and superhydrophilicity by alternation of ultraviolet (UV) irradiation and dark storage with keeping a good oleophobicity on the modified surface treated with the anatase-type titanium oxide composite.     

Multielemental characterization of several brands of fullerenes and fullerene precursors by instrumental neutron activation analysis

The characterization of the purity of fullerenes is based on the concept of defining the percentage amount of the main component (e.g., C(60), C(70), etc.) versus the minor fractions or microfractions of the homologue species and/or other polycyclic organic compounds. It has also to be considered that fullerene products may be contaminated in some degree by element impurities as well, both from the production processes and from the various precursor materials themselves. We report here for the first time detailed data on trace element impurities in various fullerene precursors as well as in the main C(60) and C(70) fullerene products of different producers, measured by instrumental neutron activation analysis. The concentration distributions of about 35 trace elements have been studied, including the determination of the relevant limits of detection. It could be established that all fullerene materials investigated contain a broad scale of trace elements distributed within a fairly wide concentration range, from ppb (ng/g) up to ppm (μg/g) levels. For some impurity elements, extremely high concentration levels were found, indicating that elemental impurities have to be considered when studying the electrical, magnetic, and other features of the fullerenes.     

MA封端的光敏聚酰亚胺的合成与表征

光敏聚酰亚胺以其优良的性能在许多高新技术领域中得到了广泛的应用,是当今国内外学者的研究热点。采用均苯四酸二酐(PMDA)与4,4’-二氨基二苯醚(ODA)、顺丁烯二酸酐(MA)进行共聚,实验表明以MA封端效果较好,比较成功的在聚酰亚胺分子链中引入光敏基团,采用IR、TGA等测试手段对聚合物的结构与性能进行了表征和研究。     

Synthesis of encapsulating and hollow onion-like fullerenes from coal

Onion-like fullerenes (OLFs) with different structures were synthesized from coal by radio frequency plasma. The morphologies and structures of the products were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) techniques. The results clearly indicated that two types of uniform OLFs with high purity could be prepared from coal, and Fe in coal favored the growth of OLFs.     

富勒烯/碳纳米管杂化材料的制备及表征

本文通过一种简易的化学方法成功制备了富勒烯/碳纳米管杂化材料。首先采用强酸氧化处理多壁碳纳米管使其表面产生羟基和羧基等官能基团,再将氧化处理后的碳纳米管与六亚甲基二异氰酸酯反应,通过羟基和羧基基团与异氰酸根的反应对多壁碳纳米管进行修饰,最后利用富勒醇表面的羟基与碳纳米管表面异氰酸之间的反应制备出富勒烯/碳纳米管杂化材料。产品采用傅立叶变换红外光谱(FTIR)、透射电镜(TEM)和热重分析(TGA)等手段进行了分析和表征。结果表明,成功实现了富勒烯与碳纳米管的化学组装。     

Synthesis and properties of novel photosensitive poly(arylene ether sulfone) containing chalcone moiety in the main chain

A new series of photosensitive poly(arylene ether sulfone)s containing chalcone moiety in the main chain were synthesized from 4,4′-dihydroxychalcone (4DHC), 4,4′-difluorodiphenylsulfone (DFDPS) and bisphenol A (BPA). This series of polymers were characterized by ¹H NMR, FT-IR, UV spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The polymers were stable up to 400 °C, which indicates that the polymers possess good thermal properties. The polymers were found to be soluble in polar solvents and chlorinated solvents. However, the polymers were insoluble in hydrocarbons and in hydroxyl group-containing solvents. After the irradiation of UV light, the thin polymer film was crosslinked to give an insoluble film in the absence of a photoinitiator or sensitizers. The rate of photocrosslinking was also examined and discussed.     

水下电弧放电法制备洋葱状富勒烯

探索了纯石墨电极在水中放电制备洋葱状富勒烯（Onion-like fullerenes，OLFs）的过程和工艺。用高分辨透射电镜（High resolution transmission electron microscope。HRTEM）对生成的OLFs进行了形貌、结构的观察与表征。分析结果表明制得的OLFs具有各种不同形状的内核。石墨化程度很高，直径分布在5nm～40nm范围内。在一定范围内随着电流强度的增大OLFs的产量和产率都有不同程度的提高。     

液苯介质放电制备洋葱状富勒烯

以液体苯(C6H6)为放电介质,石墨做电极,成功地制备了洋葱状富勒烯(Onion-like Fullerenes,OLFs)。重点考察了电流对OLFs产量的影响,利用高分辨透射电镜(HRTEM)和X-射线衍射(XRD)对所得产物进行了表征。结果表明:电流大小是影响OLFs产量的主要因素,所制OLFs直径分布可控制在10nm~30nm范围内。