scholarly journals Synthesis and Characterization of Amphiphilic Diblock Copolymer by Reverse Iodine Transfer Polymerization (RITP)

2019 ◽  
Vol 27 (2) ◽  
pp. 185-202 ◽  
Author(s):  
Wahiba Chaibi ◽  
Lamia Bennabi ◽  
Imene Boukhouya ◽  
Kaddour Guemra
Keyword(s):  
Diblock Copolymer ◽  
Self Assembly ◽  
Molecular Iodine ◽  
Water Soluble ◽  
H Nmr ◽  
Wide Range ◽  
Dynamic Light Scattering Technique ◽  
Ft Ir ◽  
Iodine Transfer

Abstract Iodine transfer radical homo- and diblock copolymerization of N-[3-(dimethylamino)propyl] methacrylamide (DMAPMA) with methyl methacrylate (MMA) were carried out in the presence of iodine I2 and 2,2′-azobis(isobutyronitrile) (AIBN) as chain transfer agent and initiator, respectively. Using reverse iodine transfer polymerization (RITP) method based on the in situ generation of transfer agents using molecular iodine I2. The homopolymer and copolymer were characterized by FT-IR and 1H NMR. The self-assembly behaviours of diblock copolymer in water are studied by viscosity and tensiometry techniques. The water-soluble fraction of P(DMAPMA-b-MMA) block copolymer formed micelles which were investigated at 25°C in water at 0.2 mg.mL−1 concentration using a tensiometry device. Dynamic light scattering technique (DLS) was performed over a wide range of concentration to determine hydrodynamic size of the aggregates.

Lyotropic liquid crystalline phthalocyanines containing 4-((S)-3,7-dimethyloctyloxy)phenoxy moieties

2017 ◽  
Vol 21 (01) ◽  
pp. 16-23 ◽  
Author(s):  
Sibel Eken Korkut ◽  
Hale Ocak ◽  
Belkıs Bilgin-Eran ◽  
Dilek Güzeller ◽  
M. Kasım Şener
Keyword(s):  
Liquid Crystalline ◽  
Spectroscopic Properties ◽  
The Novel ◽  
H Nmr ◽  
Vis Spectroscopy ◽  
Wide Range ◽  
Ft Ir ◽  
Aggregation Behaviors ◽  
Mesomorphic Properties ◽  
Thermotropic Liquid Crystalline Behavior

The novel metal free phthalocyanine and its copper complex which are octa-substituted at the peripheral positions with 4-(([Formula: see text]-3,7-dimethlyoctyloxy)phenoxy moieties were synthesized and characterized by FT-IR, 1H NMR and mass spectroscopy. Their mesomorphic properties were studied by polarizing optical microscopy. The spectroscopic properties and aggregation behaviors of the novel phthalocyanines were also investigated by UV-vis spectroscopy in different solvents with same concentration as well as in a wide range of concentrations of chloroform. Both compounds with chloroform and [Formula: see text]-dodecane clearly show the lyotropic columnar mesophase in a wide temperature range whereas thermotropic liquid crystalline behavior for both compounds is not observed. Both of these novel compounds show no aggregation in toluene, tetrahydrofuran, dichloromethane and chloroform.

Aqueous suspension of amphiphilic diblock copolymer nanoparticles prepared in situ from a water-soluble poly(sodium acrylate) alkoxyamine macroinitiator

Soft Matter ◽  
2006 ◽  
Vol 2 (3) ◽  
pp. 223 ◽  
Author(s):  
Guillaume Delaittre ◽  
Julien Nicolas ◽  
Catherine Lefay ◽  
Maud Save ◽  
Bernadette Charleux
Keyword(s):  
Diblock Copolymer ◽  
Aqueous Suspension ◽  
Water Soluble ◽  
Sodium Acrylate ◽  
Amphiphilic Diblock Copolymer ◽  
Soluble Poly

In-situ visualization and order quantification of symmetric diblock copolymer directed self-assembly

2013 ◽  
Vol 543 ◽  
pp. 148-152 ◽  
Author(s):  
M. Salaün ◽  
M. Le Gallic ◽  
E. Picard ◽  
M. Zelsmann
Keyword(s):  
Diblock Copolymer ◽  
Self Assembly ◽  
In Situ Visualization

scholarly journals An efficient Pd–NHC catalyst system in situ generated from Na2PdCl4 and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water

2017 ◽  
Vol 13 ◽  
pp. 1735-1744 ◽  
Author(s):  
Nan Sun ◽  
Meng Chen ◽  
Liqun Jin ◽  
Wei Zhao ◽  
Baoxiang Hu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Imidazole Ring ◽  
Catalyst System ◽  
Water Soluble ◽  
Imidazolium Salts ◽  
Heck Reactions ◽  
Imidazolium Salt ◽  
Simple Method ◽  
Wide Range

Three PEG-functionalized imidazolium salts L1–L3 were designed and prepared from commercially available materials via a simple method. Their corresponding water soluble Pd–NHC catalysts, in situ generated from the imidazolium salts L1–L3 and Na2PdCl4 in water, showed impressive catalytic activity for aqueous Mizoroki–Heck reactions. The kinetic study revealed that the Pd catalyst derived from the imidazolium salt L1, bearing a pyridine-2-methyl substituent at the N3 atom of the imidazole ring, showed the best catalytic activity. Under the optimal conditions, a wide range of substituted alkenes were achieved in good to excellent yields from various aryl bromides and alkenes with the catalyst TON of up to 10,000.

scholarly journals In situ kinetic measurements of α-synuclein aggregation reveal large population of short-lived oligomers

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245548
Author(s):  
Enrico Zurlo ◽  
Pravin Kumar ◽  
Georg Meisl ◽  
Alexander J. Dear ◽  
Dipro Mondal ◽  
...  
Keyword(s):  
Self Assembly ◽  
Large Population ◽  
Paramagnetic Resonance ◽  
Kinetic Measurements ◽  
Toxic Species ◽  
Self Assembling ◽  
Wide Range ◽  
Electron Paramagnetic

Knowledge of the mechanisms of assembly of amyloid proteins into aggregates is of central importance in building an understanding of neurodegenerative disease. Given that oligomeric intermediates formed during the aggregation reaction are believed to be the major toxic species, methods to track such intermediates are clearly needed. Here we present a method, electron paramagnetic resonance (EPR), by which the amount of intermediates can be measured over the course of the aggregation, directly in the reacting solution, without the need for separation. We use this approach to investigate the aggregation of α-synuclein (αS), a synaptic protein implicated in Parkinson’s disease and find a large population of oligomeric species. Our results show that these are primary oligomers, formed directly from monomeric species, rather than oligomers formed by secondary nucleation processes, and that they are short-lived, the majority of them dissociates rather than converts to fibrils. As demonstrated here, EPR offers the means to detect such short-lived intermediate species directly in situ. As it relies only on the change in size of the detected species, it will be applicable to a wide range of self-assembling systems, making accessible the kinetics of intermediates and thus allowing the determination of their rates of formation and conversion, key processes in the self-assembly reaction.

scholarly journals An Amino-Chain Modified β-cyclodextrin: A Supramolecular Ligand for Pd(OAc)2 Acceleration in Suzuki–Miyaura Coupling Reactions in Water

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 111 ◽  
Author(s):  
Vijay Shinde ◽  
Daham Jeong ◽  
Seunho Jung
Keyword(s):  
2D Nmr ◽  
Water Soluble ◽  
High Catalytic Activity ◽  
Coupling Reactions ◽  
Arylboronic Acid ◽  
Complex Catalyst ◽  
Cross Coupling Reactions ◽  
Wide Range ◽  
Ft Ir ◽  
Soluble Class

A well-designed and synthesized water-soluble class of β-cyclodextrin supported palladium complex PdLn@Et-β-CD could efficiently validate high catalytic activity and act as a supramolecular platform for phosphine-free Suzuki–Miyaura cross‐coupling reactions between arylboronic acid/ arylboronic ester and aryl halides in water under mild conditions. The presented novel PdLn@Pr-β-CD complex catalyst was characterized by NMR, XRD, FT-IR, and DSC analysis. Furthermore, the role of the PdLn@Et-β-CD fragment in the reaction mechanism studied by molecular complexation was proposed based on FT-IR, 2D NMR (ROESY) spectroscopy, FE-SEM, and DSC spectroscopic analysis. The important benefits of this technique comprise simple phosphine-free preparation of the palladium catalyst, a wide range of functional-group tolerance, and easy recyclability; this method, furthermore, eschews hazardous reagents or solvents.

Monitoring pattern formation in drying and wetting dispersions of gold nanoparticles by ESEM

2015 ◽  
Vol 181 ◽  
pp. 281-298 ◽  
Author(s):  
Casper Kunstmann-Olsen ◽  
Domagoj Belić ◽  
Mathias Brust
Keyword(s):  
Gold Nanoparticles ◽  
Self Assembly ◽  
Early Stage ◽  
Environmental Scanning Electron Microscopy ◽  
Water Soluble ◽  
Environmental Scanning ◽  
Evaporation And Condensation ◽  
Lift Off ◽  
Poly Ethylene

We report an investigation of the self-assembly of patterns from functionalized gold nanoparticles (GNPs) by monitoring the process in situ by environmental scanning electron microscopy (ESEM) during both evaporation and condensation of the dispersant. As this method limits the choice of dispersants to water, GNPs functionalized with hydrophilic thiol ligands, containing poly(ethylene)glycol (PEG) groups, were used on a variety of substrates including pre-patterned ones. Particular emphasis was given to early stage deposition of GNPs, as well as redispersion and lift-off upon condensation of water droplets. ESEM presents a unique opportunity of directly imaging such events in situ. It was found that attractive interactions between the substrate and the GNPs are often stronger than expected once the particles have been deposited. The role of nickel perchlorate as a highly water-soluble additive was studied. It was found that entropically driven deposition of particles and decoration of surface features was enhanced in its presence, as expected.

DABCO-Directed Self-Assembly of Pyrene-Centered Porphyrin Pentamers

2013 ◽  
Vol 575-576 ◽  
pp. 123-129
Author(s):  
Zhuang Dong Yuan ◽  
Jing Xia Wang ◽  
Ning Sheng
Keyword(s):  
Self Assembly ◽  
Fluorescence Emission ◽  
The Self ◽  
Spectroscopic Methods ◽  
Assembly Process ◽  
Zinc Porphyrin ◽  
Axial Coordination ◽  
H Nmr ◽  
Wide Range ◽  
Nmr Techniques

DABCO (1, 4-diazabicyclo [2.2.2] octane) has been used in combination with pentameric zinc porphyrin-pyrene array 1 to form well-defined supramolecular arrays through axial coordination. The self-assembly process has been investigated by a wide range of spectroscopic methods including UV-vis, fluorescence emission and 1H NMR techniques.

High Temperature - FTIR Characterization of Gadolinia Doped Ceria

2010 ◽  
Vol 72 ◽  
pp. 249-254
Author(s):  
Aliye Arabaci ◽  
Nuri Solak
Keyword(s):  
High Temperature ◽  
Thermal Analyses ◽  
Water Soluble ◽  
Ex Situ ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
Ftir Characterization ◽  
Ft Ir ◽  
Xrd Techniques

Doped ceria-based (DC) materials have recently been considered as the most promising solid electrolytes for intermediate temperature solid oxide fuel cell (IT-SOFC) applications. Doped ceria is usually prepared via thermal decomposition of its water soluble salts, especially, acetates and nitrates. The properties of the obtained final product directly influenced by the starting material and the decomposition products. Therefore, it is crucial to understand the decomposition steps and intermediate products. Number of experimental work have been reported using various <em>in-situ</em> and <em>ex-situ</em> techniques such as thermogravimetry with mass spectrometry (TG/DTA-MS), X-ray diffraction with differential scanning calorimeter (XRD-DSC). However, the available literature data is limited and not reasonably in agreement with each other. High Temperature FT-IR spectroscopy, TG/DTA-MS, XRD, techniques were used and results are compared with literature. A good agreement between the thermal analyses and HT-FTIR results were obtained. Possible decomposition mechanism is discussed.

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