scholarly journals Design of High-Relaxivity Polyelectrolyte Nanocapsules Based on Citrate Complexes of Gadolinium(III) of Unusual Composition

2021 ◽  
Vol 22 (21) ◽  
pp. 11590
Author(s):  
Evgenia Burilova ◽  
Alexander Solodov ◽  
Julia Shayimova ◽  
Julia Zhuravleva ◽  
Darya Shurtakova ◽  
...  
Keyword(s):  
Citric Acid ◽  
Magnetic Relaxation ◽  
Ligand Complex ◽  
Ethylene Imine ◽  
Medium Ph ◽  
Weakly Alkaline ◽  
Transmission Electron ◽  
High Relaxivity ◽  
Poly Ethylene ◽  
Ph Range

Through nuclear magnetic relaxation and pH-metry, the details of the complexation of gadolinium(III) ions with citric acid (H4L) in water and aqueous solutions of cationic polyelectrolytes are established. It is shown that the presence of poly(ethylene imine) (PEI) in solution affects magnetic relaxation behavior of gadolinium(III) complexes with citric acid (Cit) to a greater extent than polydiallyldimethylammonium chloride (PDDC). A large increase in relaxivity (up to 50 mM−1s−1) in the broad pH range (4–8) is revealed for the gadolinium(III)–citric acid–PEI system, which is particularly strong in the case of PEI with the molecular weight of 25 and 60 kDa. In weakly acidic medium (pH 3–7), the presence of PEI results in the formation of two tris-ligand associates [Gd(H2L)3]3− and [Gd(H2L)2(HL)]4−, which do not exist in aqueous medium. In weakly alkaline medium (pH 7–10), formation of ternary complexes Gd(III)–Cit–PEI with the Gd(III)–to–Cit ratio of 1:2 is evidenced. Using transmission electron microscopy (TEM) and dynamic light scattering techniques (DLS), the formation of the particles with the size of 50–100 nm possessing narrow molecular-mass distribution (PDI 0.08) is determined in the solution containing associate of PEI with tris-ligand complex [Gd(H2L)2(HL)]4−.

scholarly journals pH-Dependence of the morphology of micelles formed by poly(2-vinylpyridine)-block-poly(ethylene oxide) copolymers in water

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Jean-François Gohy ◽  
Sandrine Mores ◽  
Sunil K. Varshney ◽  
Jian-Xin Zhang ◽  
Robert Jérôme
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ethylene Oxide ◽  
Ph Dependence ◽  
Minor Component ◽  
Transmission Electron ◽  
Poly Ethylene Oxide ◽  
Spherical Micelles ◽  
Poly Ethylene ◽  
Ph Range

AbstractThe morphology of micelles formed by two poly(2-vinylpyridine)-blockpoly( ethylene oxide) (P2VP-b-PEO) copolymers has been studied in phosphatebuffered water by dynamic light scattering and transmission electron microscopy. Spherical micelles are observed when the P2VP block is the minor component of the diblock copolymer. When P2VP dominates the composition, transition from spheres-to-rods-to-vesicles takes place in a narrow pH range that straddles the pKa of P2VP. This transition is controlled by the degree of protonation of the P2VP blocks. At high pH, the copolymer precipitates from the solution.

Controlled Aqueous Synthesis of CdSe Quantum Dots using Double-Hydrophilic Block Copolymers as Stabilizers

2018 ◽  
Vol 232 (9-11) ◽  
pp. 1281-1293 ◽  
Author(s):  
Denis Runge ◽  
Helmut Cölfen
Keyword(s):  
Quantum Dots ◽  
Block Copolymers ◽  
Analytical Ultracentrifugation ◽  
Polymer Concentration ◽  
Cdse Quantum Dots ◽  
Ethylene Imine ◽  
Aqueous Synthesis ◽  
Transmission Electron ◽  
Double Hydrophilic Block Copolymers ◽  
Poly Ethylene

Abstract We present a simple experimental procedure to obtain CdSe quantum dots from aqueous solution with a controllable size. Double-hydrophilic block copolymers consisting of a poly(ethylene glycol) block and a block of either poly(ethylene imine) or polylysine are used as stabilizers. UV/VIS absorption spectroscopy, analytical ultracentrifugation and transmission electron microscopy are used to examine the resulting quantum dots. The particle size can be simply controlled by adjusting the polymer concentration during synthesis for both block copolymers.

scholarly journals Study Structure and Properties of Nanocomposite Material Based on Unsaturated Polyester with Clay Modified by Poly(ethylene oxide)

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Tran Duy Thanh ◽  
Nguyen Dang Mao ◽  
Nguyen Thi Kim Ngan ◽  
Ha Thuc Chi Nhan ◽  
Ha Thuc Huy ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Polymer Matrix ◽  
Unsaturated Polyester ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Poly Ethylene Oxide ◽  
Hydrophobic Nature ◽  
Poly Ethylene ◽  
Alkyl Ammonium

In recent years, polymer clay nanocomposites have been attracting considerable interests in polymers science because of their advantages. There are many scientists who researched about this kind of material and demonstrated that when polymer matrix was added to little weight of clay, properties were enhanced considerably. Because clay is a hydrophilic substance so it is difficult to use as filler in polymer matrix having hydrophobic nature, so clay needs to be modified to become compatible with polymer. In this study, poly(ethylene oxide) was used as a new modifier for clay to replace some traditional ionic surfactants such as primary, secondary, tertiary, and quaternary alkyl ammonium or alkylphosphonium cations having the following disadvantages: disintegrate at high temperature, catalyze polymer degradation, and make nanoproducts colorific, and so forth. In order to evaluate modifying effect of poly(ethylene oxide), modified clay products were characterize d by X-ray spectrum. Then organoclay was used to prepare nanocomposite based on unsaturated polyester. Morphology and properties of nanocomposites were measure d by X-ray diffraction, transmission electron microscopy, tensile strength, and thermal stability. The results showed that clay galleries changed to intercalated state in the nanocomposites. Properties of nanocomposites were improved a lot when the loading of the organoclay was used at 1 phr.

Linear Poly(ethylene imine)-Based Hydrogels for Effective Binding and Release of DNA

2014 ◽  
Vol 15 (4) ◽  
pp. 1124-1131 ◽  
Author(s):  
Christoph Englert ◽  
Lutz Tauhardt ◽  
Matthias Hartlieb ◽  
Kristian Kempe ◽  
Michael Gottschaldt ◽  
...  
Keyword(s):  
Ethylene Imine ◽  
Linear Poly ◽  
Poly Ethylene

Microgels composed of poly(ethylene imine) and carboxymethoxycoumarin: pH-dependent and photodependent integrity

2012 ◽  
Vol 129 (2) ◽  
pp. 644-651 ◽  
Author(s):  
Hyun Ju Cha ◽  
Jing Dai ◽  
Jin-Chul Kim
Keyword(s):  
Ethylene Imine ◽  
Ph Dependent ◽  
Poly Ethylene

Study on desorption of Mn, Fe, and Mg from TMP and evaluation of the complexing strength of different chelating agents using side reaction coefficients 10th EWLP, Stockholm, Sweden, August 25–28, 2008

Holzforschung ◽  
2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Kim Granholm ◽  
Pingping Su ◽  
Leo Harju ◽  
Ari Ivaska
Keyword(s):  
Citric Acid ◽  
Metal Ions ◽  
Chelating Agents ◽  
Side Reaction ◽  
Sodium Dithionite ◽  
Thermomechanical Pulp ◽  
Peroxide Bleaching ◽  
Ph Values ◽  
Reducing Environment ◽  
Ph Range

Abstract Chelation of thermomechanical pulp (TMP) was studied in this work. The desorption of Mn, Fe, and Mg due to their impact on peroxide bleaching was investigated. The desorption experiments were performed with EDTA, citric acid, oxalic acid, and formic acid as chelating agents at different pH. Chelation experiments with EDTA were carried out at pH 3–11. Sodium dithionite was used as the reducing agent in studying chelation with EDTA in a reducing environment. Mn was very effectively desorbed with EDTA from TMP at pH <10 and the reducing environment further improved the removal of all the studied metal ions from TMP with EDTA. Citric acid also removed Mn effectively from TMP at pH 5. The thermodynamic stability constants of different metal chelates do not present the correct picture of how strongly the metal ions are bound by the chelating agents in different conditions. But by means of the side reaction coefficients (α M(L)-coefficients) it is also theoretically possible to evaluate and compare the real binding strengths between the metal ions and different chelating agents at varying pH values and other solution conditions. In this study, a theory is given for the calculation of side reaction coefficients. Values of the α M(L)-coefficients, for the pH range 0–14, are presented for EDTA, DTPA, and also for some other new potential environmentally friendly chelating agents.

Immobilization of poly (ethylene imine) on poly (l-lactide) promotes MG63 cell proliferation and function

2009 ◽  
Vol 20 (11) ◽  
pp. 2317-2326 ◽  
Author(s):  
Zhen-Mei Liu ◽  
Soo-Yeon Lee ◽  
Sukhéna Sarun ◽  
Dieter Peschel ◽  
Thomas Groth
Keyword(s):  
Cell Proliferation ◽  
Mg63 Cell ◽  
Ethylene Imine ◽  
Poly Ethylene ◽  
And Function

scholarly journals Cation, Anion and Ion-Pair Complexes with a G-3 Poly(ethylene imine) Dendrimer in Aqueous Solution

Molecules ◽  
2017 ◽  
Vol 22 (5) ◽  
pp. 816 ◽  
Author(s):  
Matteo Savastano ◽  
Carla Bazzicalupi ◽  
Claudia Giorgi ◽  
Paola Gratteri ◽  
Antonio Bianchi
Keyword(s):  
Aqueous Solution ◽  
Ion Pair ◽  
Ethylene Imine ◽  
Poly Ethylene

Fullerene-Gold Core-Shell Structures and Their Self-Assemblies

2017 ◽  
Vol 16 (02) ◽  
pp. 1650029
Author(s):  
R. Sepahvand ◽  
S. Alihosseini ◽  
M. Adeli ◽  
P. Sasanpour
Keyword(s):  
Citric Acid ◽  
Self Assembly ◽  
Size Structure ◽  
Shell Structures ◽  
Core Shell ◽  
Hybrid Nanomaterial ◽  
Gold Core ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Gold Nps

Hybrid nanomaterials consisting of functionalized fullerene and gold nanoparticle (NP) have been synthesized. Fullerene was functionalized by citric acid and used as reducing and capping agent for preparation of gold NPs. Functionalization of fullerene by use of citric acid was performed by enzymatic and thermal approaches. The core-shell structures containing gold NPs as core and fullerene as shell (gold/fullerene) were prepared. It was found that method and density of functionalization of fullerene effect final structure and therefore their physicochemical property of hybrid nanomaterial dramatically. Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM) were used to analyze the structure of the synthesized hybrid nanomaterial and also study their self-assembly and physicochemical properties. Effect of the size, structure and morphology (e.g., agglomeration) of the synthesized hybrid nanomaterial on their UV-Vis absorption behavior has been also verified by theoretical modeling.

scholarly journals Role of Surfactants in the Properties of Poly(Ethylene Terephthalate)/Purified Clay Nanocomposites

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1397 ◽  
Author(s):  
Elaine dos Santos ◽  
Marcus Fook ◽  
Oscar Malta ◽  
Suédina de Lima Silva ◽  
Itamara Leite
Keyword(s):  
Clay Nanocomposites ◽  
Phosphonium Salts ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Alkyl Ammonium ◽  
Pet Crystallization

Purified clay was modified with different amounts of alkyl ammonium and phosphonium salts and used as filler in the preparation of PET nanocomposites via melt intercalation. The effect of this type of filler on morphology and thermal and mechanical properties of PET nanocomposites was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile properties, and transmission electron microscopy (TEM). The results showed that the mixture of alkyl ammonium and phosphonium salts favored the production of PET nanocomposites with intercalated and partially exfoliated morphologies with slight improvement in thermal stability. In addition, the incorporation of these organoclays tended to inhibit PET crystallization behavior, which is profitable in the production of transparent bottles.

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