Papers by Keyword: Self-Assembly

Abstract: In this paper, the graphene-polyaniline (PANI) nanocomposite thin film was prepared by the in situ self-assembly method for the ammonia (NH3) gas sensor application, which was characterized by scanning electron microscopy (SEM) and UV-vis spectroscopy. The NH3 sensing performance and mechanism of the nanocomposite film were investigated. The results revealed that the sensor based on graphene-polyaniline nanocomposite film exhibited better sensing properties and restorability than those of single graphene film.

Abstract: One perylenetetracarboxylic diimide (PDI) derivatives (PDI 1) linked with pyrene by flexible chain at the bay positions was synthesized and the molecular structure was characterized by ¹H NMR, MALDI-TOF mass spectra as well as elemental analysis. The molecular self-assembly were prepared from solution via a slow evaporation of solvent. The properties of these molecular aggregates were studied by electronic absorption and fluorescence spectra. The morphologies and structures were examined by scanning electronic microscopy (SEM) and X-ray diffraction (XRD) techniques. The conducting properties were evaluated by currentvoltage (IV) measurements. The results revealed highly ordered structure for these molecular self-assembly. The thin solid film fabricated from these molecular self-assembly show an electric conductivity as high as 4.85 × 10^-4 S cm^-1 under the ambient light, which means this compound might be used as a semiconductor in nanoelectronics.

Abstract: In this research, the microspheres of poly (99-dihexylfluorene) were fabricated with dichloromethane as a good solvent by self-assembly methods. The effects of poor solvent vapor, polymer concentration, and the temperature of environment on the formation of the sphere patterns were investigated. It was found that the microsphere could be easily prepared in the ethanol non-solvent vapor atmosphere. Besides, increasing the environment temperatures was advantageous to fabricate microspheres. Furthermore, the property of non-solvent vapor was a key role to the formation of the sphere.

Abstract: A series of titanium doped ordered mesoporous carbons (Ti-OMCs) were prepared by employing titanium modified resol as source for the first time. The effect of titanium content and F127 content on the microstructure of Ti-OMCs was investigated by X-ray diffraction (XRD), N₂ sorption isothermal and Transmission electron microscopy (TEM). The results showed that regularity of products decreased with the increase of titanium content. A mesophase transformation from 2-D hexagonal (P6mm) to body-centered cubic () structure can be achieved by decreasing F127 content.

Abstract: Self-assembled composite films of APTES-GA-APTES were successfully prepared on single-crystal silicon substrates through the cross-linking reaction between glutaraldehyde (GA) and two layers of 3-aminopropyltriethoxysilane (APTES). The optimal time to deposit the GA layer on the APTES monolayer was 3 h, during which most amino groups of APTES reacted with the aldehyde groups of GA to form smooth and uniform APTES-GA composite films. The further deposition of another APTES layer led to the generation of three-layer APTES-GA-APTES composite films. Compared to the APTES self-assembled monolayers, the three-layer films displayed a similar surface morphology but a reduced friction coefficient from 0.23 to 0.15 and an extended wear life from 50 s to 820 s due to the introduction of GA.

Abstract: Highly uniform and self-assembled spheroid-like microstructures of Na_0.5La_0.5MoO₄:Eu³⁺ were successfully synthesized by hexamine assisted hydrothermal route at 180 °C for 24 hours with neutral pH (7~8). Scanning electron microscope, X-ray diffraction pattern and energy dispersive X-ray analysis were used to characterize the morphology, crystal structure, size, and elements of the particles. It is found that, the particle size was well-controlled by increasing the molar concentration of the chelating agent hexamine. While, irradiating at 395 nm UV light, the emission spectra of micro-spheres shows remarkable characteristic dominance of red emission which is attributed to the transition ⁵D₀⁷F₂. Furthermore, the synthesized homogeneous and well-crystallized Na_0.5La_0.5MoO₄:Eu³⁺ microstructures will serve as an excellent phosphor candidate to produce high-quality luminescence for display devices in future.Keywords: Hydrothermal route, hexamine, self-assembly, photoluminescence

Abstract: In this paper, the bandgap characteristics of binary colloidal crystals (BCCs) constructed with polystyrene (PS) particles are analyzed, and several binary colloidal crystals were fabricated, specifically the non-close packed structures with improved vertical deposit method. The SEM images and reflectance spectra of the structures exhibit fine orderly structures obtained.

Abstract: Herein we report the first example of benzene-1,3,5-tricarboxamide bearing hydrophobic aminododecane side chains (1) which spontaneously forms supramolecular network by a hydrogen bonding interaction. The compound 1 was synthesized by Schotten-Baumann reaction of 1,3,5-benzenetricarbonyl trichloride and 1-aminododecane in the presence of N,N-diisopropylethylamine. Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), and Fourier Transform Infrared (FTIR) spectroscopies have proved the successful synthesis of 1 in 93% as white powder solid. The supramolecular organization was successfully utilized for sensing of nitrate anions by deformation of the hydrogen bonding to form inactive nitroso groups.

Abstract: An advanced LED multi-die-bonding integration using a fluidic self-assembly technique is proposed in the field of flip chip packages. Different form the conventional pick-and-place methods for a single LED die bonding, the fluidic approach is a relatively new design and a batch process, which can achieve not only die self-alignment but die self-assembly. Here, the size of LED die is 1-mm-square chip with the thickness of 0.3 mm. Due to the smaller size of LED die, the die-bonding process is still in need of finding a suitable approach and breakthrough. In this study, our design of fluidic self-assembly device is based on the experimental test and simulation results. The device design is the gas-flow channels with the magnetism. The width, height and length of each gas-flow channel are 1.1 mm, 0.5 mm, and 1 cm, respectively. With the restriction of the channel width, this structure design can control well to die self-alignment. In addition, the design of two circular structures in the channel can form a flat rim to achieve the die self-assemble. This mechanism of fluidic approach can be useful to the LED die self-alignment and self-assembly in the future batch processing.

Abstract: The present paper describes the preparation and characterization of novel biodegradable nanoparticles based on self-assembly of poly-γ-glutamic acid (γ-PGA). The nanosystems were stable inaqueous media at low pH conditions. Solubility of the systems was determined by turbidity measurements. Surface charge and mobility were measured electrophoretically. It was found that the size and size distribution of the nanosystems depends on the concentrations of γ-PGA solutions and their ratio as well as on the pH of the mixture and the order of addition. The average hydrodynamic diameters were between 150 and 330 nm. These biodegradable,self-assembling stable nanocomplexes might be useful for several biomedical applications.