Papers by Keyword: Self-Assembly

Abstract: The self-assembly system driven by hydrogen bonding has been widely used in various fields. Two hydrogen-bonded cyclophosphazene derivatives with amino groups (AGHP) and carbonyl groups (CGHP) were synthesized by introducing hydrophobic groups and amino groups and hydrophilic groups and carbonyl groups into cyclophosphazene respectively through nucleophilic substitution. After they were dissolved in oil water two phases, stable emulsion, and self-loading membrane structures were obtained through self-loading behavior. The results indicate that strong hydrogen bonding can be formed between these two cyclic phosphazene derivatives with amino and carbonyl groups. This hydrogen bonding can significantly reduce the interfacial tension between water/oil phases (from around 33 mN/m to below 7 mN/m) and improve the interfacial coverage (which can reach over 80%). Meanwhile, under the hydrogen bonding between amino and carbonyl groups, an amphiphilic self-assembled film was obtained at the water oil interface. Through contact angle testing, it was found that the hydrophilic side of this self-assembled film had a contact angle of 77.5° and the hydrophobic side had a contact angle of 124.8°.

Abstract: Localized surface plasmon phenomena of metallic nanoparticles could be utilized for sensing applications. As the particles in the vicinity results in a near-field coupling phenomenon, a higher field enhancement factor increases the sensing sensitivity. In this research, we propose a self-assembled and closely-packed Janus gold nanoparticle (AuNP) structure for application in molecular sensing. We utilize three-phase interfacial trapping and Langmuir-Schaefer method for the fabrication of Janus AuNP layer. In our case, dodecylamine (DDA) was used as the analyte for sensing assay. We found that the color of our AuNP changes from red-wine to blue in conjunction with the phase changes from colloidal to closely-packed layer that results in a red-shift absorbance peak. In the application of sensing assay, the absorbance peak is revealed blue-shifted up to ~40 nm from pristine AuNP layer due to the adsorption of DDA on the particle surfaces. Sensitivity enhancement is also expected due to the hotspot arises from the plasmonic particles in vicinity. This research could be further developed to a sensitive and quantitative molecular sensor up to colorimetric specific biosensor.

Abstract: Self-assembly is a ubiquitous process in the natural environment, and electrospinning is a simple and convenient method to fabricate nanofibers. The self-assembly of electrospun nanofibers can produce nanomaterials in one-dimension (1D), two-dimension (2D), three-dimension (3D), and even four-dimension (4D). Techniques to fabricate 1D nanomaterials have been reviewed in this paper, especially for nanofiber and nanotube. The mechanism of the fabrication of 2D nanomaterials has been also introduced which is a specific arrangement of 1D nanostructures. The applications of 2D nanomaterials have been reviewed concerning energy devices, electronic devices, and biomedicine. Additionally, 3D nanomaterials, as more complex materials, are mainly utilized in tissue engineering and some in other fields. The advantages have been highlighted to suggest the development and prospect of 4D nanomaterials. Although 4D printing technologies still remain intractable, some aspects of improvement through electrospinning are possible in terms of responsive materials and self-growth materials.

Abstract: In this paper, a composite micromachining process is introduced. By adjusting the surface microstructure, a composite coating with two kinds of materials with different characteristics was fabricated. Carbon steel is used as the substrate material, and laser processing is used to obtain the micro morphology on the substrate surface. nanoSiC particles were selected as one of the coating materials, and the SiC coating was added through the process of micropore induced nanoparticles self-assembly. Ni was selected as another coating material and added by electrodeposition. This processing method can be used to prepare multifunctional surface coating, combining the characteristics of different materials. This work can provide an idea to create more excellent multifunctional surfaces.

Abstract: Novel fluorescent nanomaterials have attracted enormous interests in the applications of illumination and display besides the traditional organic fluorophors. As potential alternatives, the environmental friendly fluorescent ultra-small organic-inorganic hybrid metal nanoclusters (size < 2 nm) is a series of powerful competitors used in illuminating field, on account of the non-poisonous, large amount of storage in earth, simple synthetic route, and relative low cost. The most important one, facile regulation of the fluorescence intensity and emission colors makes metal nanoclusters more attractive candidates for illumination application. Here, through ingeniously designing the structures of capping ligands, the highly bright copper nanoclusters are obtained, which further assemble into 2D ribbons with fluorescence quantum efficiency ascending to 36.4%. Last, the light emitting diodes with excellent performance are constructed, the emission wavelength locates at 650 nm in red region, which is suitable for plant illumination.

Abstract: In the present study, oligopeptide (TEA) and modified Pluronic F127 (M-Pluronic F127) with different mass fraction composited by intermolecular forces. And the oligopeptide/M-Pluronic F127 composite membranes were prepared and investigated. The structural parameters of the membranes were characterized by fourier transform-infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) measurements. It was found that there had strong interaction between TEA and M-Pluronic F127 and the composite films with different proportions had different surface morphology and thermal stability. The characteristics of the membranes were related to the significant changes of the self-assembly behavior of the TEA modified by M-Pluronic F127.

Abstract: Enhancement of surface-enhanced Raman scattering (SERS) by metal nanoparticles has attracted considerable interest on account of their widespread popularity of SERS-based measurements and devices ranging from life science until materials science. Current study focuses on noble metal SERS substrates with attempting to achieve high and enhanced effect by describe a plasmon-enhanced SERS substrate based on gold-silver, alloy-coated co-polymer (methyl methacrylate-styrene) colloidal sphere. Copolymer was synthesised via surfactant-free emulsion polymerization and was successfully produced a homogeneous colloidal spheres. The homogenous spheres of copolymer would promote periodic array upon fabrication and more, introducing the copolymer medium had improved the thermal degradation of the material compare to single polymer. Gold-silver alloy nanospheres was synthesised via one pot reduction method using citrate stabilizer. The nanoalloy obtained are well within the nanoscale domain (<100 nm) supported by the maximum surface plasmon resonance peak at 436 nm using UV-Visible spectroscopy. The perfect combination of our proposed alloy nanoparticles and copolymer present an ability to enhance Raman scattering by higher than 90 %. The region of high electron density of the substrate is expected to develop a new opportunities for SERS detections in wide analytical area.

Abstract: Copolymerization of 2,2,3,3,4,4,5,5-octafluoropentyl acrylate (OFPA) and acrylic acid (AA), OFPA and tert-butyl acrylate (t-BA) in presence ofdibenzylcarbonotrithioate (BTC) and polymeric RAFT-agents was studied, reactivity ratios were calculated. It was shown that type of RAFT-agent can influence on chain microstructure of obtained polymers. Aggregation behavior of obtained amphiphilic copolymers with different microstructures at the air/water interface was characterized by the Langmuir monolayer technique. The effect of the microstructureand subphase pH on the isotherm curves were shown.

Abstract: Phase behavior and supramolecular structure stability of wedge-shaped mesogens at negative temperature have been studied for the first time. The effect of geometrical confinement on water crystallization in different channels was examined. The role of local ordering of linear alkyl groups on stability of the nanochannels during water freezing was enlighten.

Abstract: In this paper, the deposition and optical properties of charge-stabilized gold nanoparticles on silicon oxide substrates is studied, which have been derivatised with (aminopropyl) triemethoxysilane. Monodispersed charged-stabilized colloidal gold nanoparticles with diameters between 20-150 nm were prepared and their self-assembly and optical properties on silica substrates is studied. Atomic force microscopy (AFM) is employed to investigate the nanoparticle monolayers ex situ. Analysis of AFM images provide evidence that the formation of the colloidal nanoparticle monolayers is governed by random sequential adsorption. The results indicate that the ionic strength of the suspension influences the spatial distribution of the nanoparticles. For all sizes of the Au nanoparticles tested, optical simulations of extinction coefficients made by finite-difference time domain (FDTD) indicate a resonance peak in the range of 510-600 nm wavelength of the visible range of the electromagnetic spectrum. The results indicate a simple and inexpensive approach of assembly of plasmonic nanostructures that can find applications in metamaterials and light waveguides.