scholarly journals Fabrication of Soft-Oxometalates {Mo132} Clusters With Novel Azobenzene Surfactants: Size Control by Micelles and Light

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhe Wang ◽  
Xuefeng Li ◽  
Shengli Chen ◽  
Jinfeng Dong
Keyword(s):  
Cyclic Voltammetry ◽  
Self Assembly ◽  
Cluster Size ◽  
Uv Light ◽  
Size Control ◽  
Main Function ◽  
Redox Potentials ◽  
Electrochemical Catalyst ◽  
Directing Effect ◽  
Conformation Transition

Soft-oxometalates (SOMs) are colloid suspensions of superstructured assemblies of polyoxometalates (POMs) and are found to be very effective photo-catalysts in a number of chemical reactions. The stabilization of SOMs generally requires legends or stabilizers, e.g., polymers and surfactants. In this paper, a light responsive azobenzene surfactant, C10AZOC2N3, was developed and used to stable {Mo132} SOMs. Various techniques such as Dynamic light scattering, TEM, UV-Vis spectra and cyclic voltammetry were employed to characterize the experimental results. The outstanding structure-directing effect of surfactant self-assembly micelles in solution on inorganic counter-anions was demonstrated. Different amount of cyclohexane was solubilized into C10AZOC2N3 micelles to successfully control the size of {Mo132} SOMs cluster. Furthermore, the clusters exposed to UV light for a certain time can be served as a second trigger to control the size of SOMs due to the trans-cis conformation transition of surfactant molecules. The redox potentials of C10AZOC2N3-{Mo132} SOMs were investigated as the cluster size varied. Interestingly, the redox potential of {Mo132} was not affected by the cluster size, indicating that the presence of surfactant did not change the main function of {Mo132} as an electrochemical catalyst, but merely assisted in the size control of SOM aggregation.

Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

2018 ◽  
Author(s):  
Elaine A. Kelly ◽  
Judith E. Houston ◽  
Rachel Evans
Keyword(s):  
Real Time ◽  
Absorption Spectroscopy ◽  
Self Assembly ◽  
Uv Light ◽  
Wormlike Micelles ◽  
Tetraethylene Glycol ◽  
Light Illumination ◽  
First Time ◽  
Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such as<i></i>drug delivery and micellar catalysis. Currently, their behaviour in the equilibrium <i>cis-</i>and <i>trans</i>-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>) using small-angle neutron scattering (SANS). We show that the incorporation of <i>in-situ</i>UV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>could switch between wormlike micelles (<i>trans</i>native state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked <i>in</i><i>-situ</i>through combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

Preparation of BSA Nanoparticles by Desolvation Technique Using Acetone as Desolvating Agent

2012 ◽  
Vol 5 (1) ◽  
pp. 1643-1647
Author(s):  
Krishna Sailaja A ◽  
Amareshwar P
Keyword(s):  
Aqueous Solution ◽  
Standard Deviation ◽  
Process Parameters ◽  
Self Assembly ◽  
Size Control ◽  
Polymeric Materials ◽  
Preparation Condition ◽  
Assembly Process ◽  
Average Size

In order to see the functionality and toxicity of nanoparticles in various food and drug applications, it is important to establish procedures to prepare nanoparticles of a controlled size. Desolvation is a thermodynamically driven self-assembly process for polymeric materials. In this study, we prepared BSA nanoparticles using the desolvation technique using acetone as desolvating agent. Acetone was added intermittently into 1% BSA solution at different pH under stirring at 700 rpm. Amount of acetone added, intermittent timeline of acetone addition, and pH of solution were considered as process parameters to be optimized. The effect of the process parameters on size of the nanoparticles was studied. The results indicated that the size control of BSA nanoparticles was achieved by adding acetone intermittently. The standard deviation of average size of BSA nanoparticles at each preparation condition was minimized by adding acetone intermittently. The intermittent addition in polymeric aqueous solution can be useful for size control for food or drug applications.  

scholarly journals Nucleation of Ga droplets self-assembly on GaAs(111)A substrates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Artur Tuktamyshev ◽  
Alexey Fedorov ◽  
Sergio Bietti ◽  
Stefano Vichi ◽  
Riccardo Tambone ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Size Distribution ◽  
Self Assembly ◽  
Cluster Size ◽  
Droplet Size Distribution ◽  
Local Environment ◽  
The Self ◽  
Critical Cluster ◽  
Droplet Nucleation ◽  
High Degree

AbstractWe investigated the nucleation of Ga droplets on singular GaAs(111)A substrates in the view of their use as the seeds for the self-assembled droplet epitaxial quantum dots. A small critical cluster size of 1–2 atoms characterizes the droplet nucleation. Low values of the Hopkins-Skellam index (as low as 0.35) demonstrate a high degree of a spatial order of the droplet ensemble. Around $$350\,^{\circ }\hbox {C}$$ 350 ∘ C the droplet size distribution becomes bimodal. We attribute this observation to the interplay between the local environment and the limitation to the adatom surface diffusion introduced by the Ehrlich–Schwöbel barrier at the terrace edges.

Self-Assembly of Monolayers of Submicron Sized Particles on Thin Liquid Films

2013 ◽  
Author(s):  
Shriram Pillapakkam ◽  
N. A. Musunuri ◽  
P. Singh
Keyword(s):  
Electric Field ◽  
Self Assembly ◽  
Uv Light ◽  
Capillary Forces ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Liquid Interfaces ◽  
Uv Curable ◽  
Particle Monolayer ◽  
Uv Curable Resin

In this paper, we present a technique for freezing monolayers of micron and sub-micron sized particles onto the surface of a flexible thin film after the self-assembly of a particle monolayer on fluid-liquid interfaces has been improved by the process we have developed where an electric field is applied in the direction normal to the interface. Particles smaller than about 10 microns do not self-assemble under the action of lateral capillary forces alone since capillary forces amongst them are small compared to Brownian forces. We have overcome this problem by applying an electric field in the direction normal to the interface which gives rise to dipoledipole and capillary forces which cause the particles to arrange in a triangular pattern. The technique involves assembling the monolayer on the interface between a UV-curable resin and another liquid by applying an electric field, and then curing the resin by applying UV light. The monolayer becomes embedded on the surface of the solidified resin film.

The influence of the host–guest interaction on the oxidation of natural flavonoid dyes

2011 ◽  
Vol 76 (12) ◽  
pp. 1651-1667 ◽  
Author(s):  
Šárka Ramešová ◽  
Romana Sokolová ◽  
Ilaria Degano ◽  
Magdaléna Hromadová ◽  
Miroslav Gál ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Inclusion Complex ◽  
Fluorescence Intensity ◽  
Oxidation Product ◽  
Aqueous Media ◽  
Electrochemical Methods ◽  
Redox Potentials ◽  
Decomposition Products ◽  
Degradation Processes ◽  
Bioorganic Compounds

The influence of the molecular cavity protection on degradation processes of bioorganic compounds quercetin and luteolin used as the original dyes in old tapestries was studied. The degradation processes were studied by electrochemical methods in aqueous media. The products of the exhaustive electrolysis were separated and identified by GC-MS analysis. Cyclic voltammetry characteristics indicate that the inclusion complex is formed. The inclusion affects the redox potentials of both oxidation waves related to the different dissociation forms of the flavonoid molecule. It was shown that decomposition products formed by the oxidation of quercetin are stabilized in the cavity of β-cyclodextrin, including the main oxidation product 2(3′,4′-dihydroxybenzoyl)-2,4,6-trihydroxybenzofuran-3(2H)-one. The formation of the 1:1 inclusion complex of luteolin with β-cyclodextrin is supported by the enhancement of fluorescence intensity. In the case of quercetin, a decrease of fluorescence intensity occurs when 1:1 inclusion complex with β-cyclodextrin is formed.

scholarly journals PhotoATRP Induced Self-Assembly (PhotoATR-PISA) Enables Simplified Synthesis of Responsive Polymer Nanoparticles in One-Pot

2020 ◽  
Author(s):  
Ali Shahrokhinia ◽  
Randall Scanga ◽  
Priyanka Biswas ◽  
James Reuther
Keyword(s):  
Self Assembly ◽  
Glycidyl Methacrylate ◽  
Uv Light ◽  
Copper Catalyst ◽  
Crosslinking Agent ◽  
Polymer Nanoparticles ◽  
One Pot ◽  
Responsive Polymer ◽  
Catalyst Systems ◽  
First Time

<p><b>ABSTRACT:</b> Photo-controlled atom transfer radical polymerization (PhotoATRP) was implemented, for the first time, to accomplish polymerization induced self-assembly (PISA) mediated by UV light (λ = 365 nm) using ppm levels (ca. < 20 ppm) of copper catalyst at ambient temperature. Using Cu<sup>II</sup>Br<sub>2</sub>/tris(pyridin-2-ylmethyl)amine (TPMA) catalyst systems, PISA was per-formed all in one-pot starting from synthesis of solvophilic poly(oligo(ethylene oxide) methyl ether methacrylate) (POEGMA) blocks to core-crosslinked nanoparticles (NPs) utilizing poly(glycidyl methacrylate) (PGMA) and N,N-cystamine bismethacrylamide (CBMA) as the solvophobic copolymer and crosslinking agent, respectively. Sequential chain-extensions were performed for PGMA demonstrating capabilities for accessing multi-block copolymers with temporal control via switching the UV light on and off. Further, core-crosslinking of PISA nanoparticles was performed via the slow incorporation of the CBMA enabling one-pot crosslinking during the PISA process. Finally, the disulfide installed in the CBMA core-crosslinks allowed for the stimuli-triggered dissociation of nanoparticles using DL-dithiothreitol at acidic pH.</p>

Self-Assembly Growth and Size Control of Silver Nanocrystals for Nonvolatile Memory Applications

2009 ◽  
Vol 610-613 ◽  
pp. 585-590 ◽  
Author(s):  
Li Wang ◽  
Hong Fang Sun ◽  
Hui Hua Zhou ◽  
Jing Zhu
Keyword(s):  
Self Assembly ◽  
Nonvolatile Memory ◽  
Single Layer ◽  
Size Control ◽  
Transmission Electron ◽  
Sputtering Power ◽  
High Uniformity ◽  
Memory Applications ◽  
Magnetic Sputtering ◽  
The Relationship

A film with a single-layer of size controlled silver nanocrystals embedded in silicon dioxide (SiO2) dielectric film by magnetic sputtering has been fabricated for nonvolatile memory applications. The effects of sputtering power, deposition time and substrate temperature on Ag nanocrystals formation were investigated. Transmission electron microscopy (TEM) images showed the as-prepared Ag nanocrystals had high uniformity in their size and distribution. The relationship between Ag nanocrystal size, density and electron storage capability as well as date retention time has been discussed.

Self-assembly of mesoporous Bi-S-TiO2 composites for degradation of industrial dinitrotoluene solution under UV light

2017 ◽  
Vol 24 (10) ◽  
pp. 9585-9593 ◽  
Author(s):  
Qiang Gan ◽  
Guoqi Feng ◽  
Xia Liu ◽  
Hairu Shang ◽  
Changgen Feng
Keyword(s):  
Self Assembly ◽  
Uv Light

scholarly journals Tunable structural color of bottlebrush block copolymers through direct-write 3D printing from solution

2020 ◽  
Vol 6 (24) ◽  
pp. eaaz7202 ◽  
Author(s):  
Bijal B. Patel ◽  
Dylan J. Walsh ◽  
Do Hoon Kim ◽  
Justin Kwok ◽  
Byeongdu Lee ◽  
...  
Keyword(s):  
3D Printing ◽  
Self Assembly ◽  
Three Dimensional ◽  
Size Control ◽  
Functional Materials ◽  
Domain Size ◽  
Direct Write ◽  
Processing Scheme ◽  
Solvent Vapor ◽  
Robust Processing

Additive manufacturing of functional materials is limited by control of microstructure and assembly at the nanoscale. In this work, we integrate nonequilibrium self-assembly with direct-write three-dimensional (3D) printing to prepare bottlebrush block copolymer (BBCP) photonic crystals (PCs) with tunable structure color. After varying deposition conditions during printing of a single ink solution, peak reflected wavelength for BBCP PCs span a range of 403 to 626 nm (blue to red), corresponding to an estimated change in d-spacing of >70 nm (Bragg- Snell equation). Physical characterization confirms that these vivid optical effects are underpinned by tuning of lamellar domain spacing, which we attribute to modulation of polymer conformation. Using in situ optical microscopy and solvent-vapor annealing, we identify kinetic trapping of metastable microstructures during printing as the mechanism for domain size control. More generally, we present a robust processing scheme with potential for on-the-fly property tuning of a variety of functional materials.

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