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1.
Poly(ethylene oxide) macromonomers carrying methoxy group on the one (α-) end and methacryloyloxyhexyl or methacryloyloxydecyl
group on the other (ω-) end were prepared, homopolymerized in water, and dispersion-copolymer-ized with styrene or methyl
methacrylate in a methanol–water mixture. They were found to polymerize more rapidly and to produce stable polystyrene dispersions
more effectively, as compared to the corresponding macromonomers carrying either α-methoxy and or α-dodecyloxy and ω-methacryloyloxy
end groups. Thus, the amphiphilic constitution of the macromonomers such that favors the polymerizing methacrylate end groups
to locally concentrate into the micelle core or to the particle surface while the poly(ethylene oxide) chains extending to
the medium appears to be most important in enhancing their polymerizability and effectiveness as reactive steric stabilizers.
On the other hand, stable poly(methyl methacry-late) particles with a number of craters or pleats on the surface were produced
with a PEO macromono-mer with α-methoxy and ω-methacryl-oyloxy end groups.
Received: 4 September 1996 Accepted: 18 October 1996 相似文献
2.
Polyelectrolytes with amphiphilic counterions, PEACs, are water insoluble because the amphiphiles self-assemble into highly charged micelles that strongly associate with the equally highly charged polyions. However, in the presence of water soluble cyclodextrins (CDs) that form inclusion complexes with the amphiphiles and prevent micellization, PEACs become soluble as the dispersed amphiphiles behave essentially as simple monovalent counterions. In this paper, we illustrate, by example, how strongly the ternary phase behavior of PEAC:CD:water depends on the polyion flexibility; for a highly flexible polyion (polyacrylate) the amphiphilic aggregates dictate the phase behavior, whereas a much stiffer polyion (DNA) itself dictates liquid crystalline ordering. 相似文献
3.
D. Duracher F. Sauzedde A. Elaïssari C. Pichot L. Nabzar 《Colloid and polymer science》1998,276(10):920-929
In a previous paper [1], the synthesis of various polystyrene– poly[NIPAM] core–shell latexes bearing cationic amidino and/or
amino charges has been described. Several colloidal properties of these cationic latexes have been charac-terized such as:
particle size, surface charge density, electrophoretic mobility and finally colloidal stability. Due to the poly[NIPAM]-rich
layer in the shell, it was found that temperature played a significant role on all these properties, a LCST around 33 °C being
exhibited. In addition, ionic strength was also found to affect the colloidal behavior of these latexes, the largest effect
being observed with latexes having both amidino and amino surface charges. The critical coagulation concentra-tions (CCC)
of the various latexes above and below the LCST were determined, highlighting the contribution of electrostatic and steric
repulsive forces to the stability of these particles.
Received: 20 January 1998 Accepted: 8 June 1998 相似文献
4.
J. M. Peula-Garcia R. Hidaldo-Alvarez F. J. de las Nieves 《Colloid and polymer science》1997,275(2):198-202
The latex agglutination immunoassay technique uses polymer colloids as a carrier for the adsorbed proteins to enhance the
antigen–antibody reaction. Competitive co-adsorption of IgGaCRP and m-BSA proteins on polystyrene latexes with different functionality
(sulfate and sulfonate groups) was carried out looking for the increase in the immunoreactivity and colloid stability of latex–protein
complexes. The preferential adsorption of a protein is also studied, comparing both surface types.
Regarding the application in the development of a diagnostic test system, it is necessary to study the latex–protein complexes
from an electrokinetic and colloid stability point of view.
The presence of protein on the surface latex shifts the iso-electric point (i.e.p.) of the latex–protein complexes to pH values
near the i.e.p. of the protein which is the majority. Thus by the adsorption of m-BSA we can obtain complexes with the i.e.p.
near pH 5 and, therefore, with a significant electrostatic repulsion at neutral pH.
Due to the higher surface charge density of the sulfonate latexes there is a higher adsorption of both proteins, which can
provide a better colloidal stability (by the adsorption of m-BSA) and a better immunoreactivity (by the adsorption of IgG).
Received: 27 March 1996 Accepted: 1 September 1996 相似文献
5.
Javier Revilla Abdelhamid Ela?&#x;ssari Pascal Carriere Christian Pichot 《Journal of colloid and interface science》1996,180(2):405
The adsorption of bovine serum albumin (BSA) onto polystyrene latexes bearing various amounts of sugar moieties has been investigated as a function of pH and ionic strength and the results were compared to those for bare polystyrene latexes having negative surface charges. The functionalized latexes were produced by seeded copolymerization of (0.3 μm) liposaccharidic monomer onto polystyrene particles obtained by soap-free emulsion polymerization of styrene using potassium persulfate as initiator. At first, the electrophoretic mobility behavior of the various latexes was examined as a function of pH: a significant decrease was observed in the case of saccharide-containing latex particles compared to the bare particles. The adsorption of BSA onto these latexes exhibited a reduced amount of adsorbed BSA for those latex particles bearing saccharide groups. This adsorbed amount depends on the yield of saccharidic monomer incorporated onto the surfaces of the latex particles. 相似文献
6.
A spectroturbidimetric method adaptable to routine clinical practice is proposed for estimating the sizes of insoluble immune
complex particles in poly(ethylene glycol) (PEG)-treated blood serum. In order to determine average particle diameter d from wavelength exponent w (the exponent in the power approximation of turbidity spectra), calibration is performed relative to polystyrene latexes,
d (nm) = exp(8.2 − 0.9w). To optimize the method, the influence of PEG concentration and antigen/antibody ratio on the average sizes of formed particles
is studied by the example of a model antigen (tetanic toxoid)-antibody (human antitoxoid γ-globulin) system. The optimized
procedure is used to analyze human blood serum. It is shown that, in the presence of 3% PEG, the average particle sizes and
volumes of the insoluble immune complexes are significantly different in healthy individuals and patients with rheumatoid
arthritis. These differences are in significant correlation with the rheumatoid factor level determined in sera through the
standard latex agglutination test. 相似文献
7.
Effects of oligonucleotide adsorption on the physicochemical characteristics of a nanoparticle-based model delivery system for antisense drugs 总被引:4,自引:0,他引:4
N. Götting H. Fritz M. Maier J. von Stamm T. Schoofs E. Bayer 《Colloid and polymer science》1999,277(2-3):145-152
Cationic polystyrene nanoparticles, as a model drug carrier system for nucleic acids, are capable of binding negatively charged
oligonucleotides by multiple electrostatic interactions. The effect of the adsorption of phosphorothioate oligonucleotides
on the physicochemical properties of the carrier system was investigated for uncoated and sterically stabilized latex particles.
Turbidity measurements and photon-correlation spectroscopy indicate that the colloidal stability of the nanoparticle-oligonucleotide
conjugates is influenced by the number of oligonucleotides adsorbed on the carrier. Especially in the case of the uncoated
material, a destabilizing effect has been observed up to oligonucleotide concentrations of 2.7 μmol/g polymer. Strikingly,
at higher concentrations the latexes exhibit colloidal stability similar to the oligonucleotide-free samples. These results
were correlated to zeta-potential measurements demonstrating a reversal from positive to negative values of the zeta potential
with increasing oligonucleotide concentration. The points of zero charge of the particles are in the region of maximum coagulation.
These findings were compared to adsorption studies and calculations based on the random sequential adsorption model. It appears
that at first the colloidal stability of the carrier systems is diminished with increasing oligonucleotide adsorption, while
higher surface coverages lead to a significant reduction in coagulation. At the saturation level the surface coverage can
be considered as a monolayer of “side-on” adsorbed molecules and the conjugates exhibit colloidal stability similar to the
bare particles without adsorbed molecules.
Received: 20 April 1998 Accepted: 16 July 1998 相似文献
8.
9.
Inclusion complexes of poly(ethylene oxide) with α-cyclodextrin are the key compounds in the synthesis of polyrotaxanes. These
complexes prepared in aqueous solutions contain free cyclodextrin, which cocrystallizes with the major reaction product. These
complexes dissociate upon dissolution in DMF and DMSO to form cyclodextrin and pseudopolyrotaxanes with a low cyclodextrin
content. Polyrotaxane was synthesized with the use of poly(ethylene oxide)-α,ω-bis-amine as a linear component. The end-groups
of the polymer in the inclusion complex were modified by the reaction with 2,4-dinitrofluorobenzene. A procedure was developed
for purification of a polyrotaxane with high cyclodextrin content.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1914–1918, August, 2005. 相似文献
10.
The behaviour of small solid particles and liquid droplets at fluid interfaces is of wide interest, in part because of the
roles they play in the stability of foams and emulsions. Here we focus on solid particles at liquid interfaces, both singly
and in highly structured monolayers. We briefly mention small oil lenses on water in connection with the determination of
line tension, τ. Particles are surface-active in the sense that they often adhere quite strongly to liquid surfaces, although
of course they are not usually amphiphilic. The three-phase contact line around a particle at an interface is associated with
an excess free energy resulting in a tendency of the line to contract (positive τ, which is a 1D analogue of surface tension)
or to expand (negative τ). Positive line tension acts so as to push the contact angle of a particle with the fluid interface
further away from 90°, i.e. to force the particle towards the more “wetting” of the two bulk phases. It also leads to activation
barriers to entry and departure of particles from an interface. The behaviour of particle monolayers at octane/water interfaces
is also discussed . It is found that, for monodisperse spherical polystyrene particles containing ionisable sulphate groups
at the surface, highly ordered monolayers are formed. This appears to result from very long range electrostatic repulsion
mediated through the oil phase. Surface pressure–surface area isotherms are discussed for particle monolayers and it is shown,
using light microscopy, that at monolayer “collapse” particles are not expelled from the monolayers but rather the monolayer
folds, remaining intact. This has an important bearing on methods, involving the use of the Langmuir trough, for the experimental
determination of contact angles and line tensions in particulate systems.
Received: 18 July 1999/Accepted: 30 August 1999 相似文献
11.
A series of polyampholytes of sodium-2-acrylamido-2-methylpropanesulfonate (NaAMPS) and 2-(methacryloyloxy) ethyltrimethylammonium chloride (MADQUAT) has been synthesized by free radical polymerization in microemulsions. The optimization of the formulation was, by a selection procedure, based on the hydrophile-lipophile balance (HLB) of the nonionic surfactants and solubility parameters of the different components. Both ionomers play an important role in the formulation owing to their amphiphilic and electrolyte characters as confirmed by surface tension and turbidimetry experiments. These effects control the HLB and interfacial properties of the microemulsions. The results are semi-quantitatively interpreted from the cohesive energy ratio (CER) concept. The reaction products are stable inverse latexes consisting of high molecular weight copolymers entrapped in water droplets particles and dispersed in an isoparaffinic oil. 相似文献
12.
In this work turbidimetric and nephelometric techniques have been used to study the homocoagulation of aqueous dispersions
of uniform spherical particles of surfactant-free latexes. Cationic and anionic latexes of similar particle sizes (361 and
370 nm) and different surface charge densities (+16.4 and −3.6 μC/cm2) were used throughout. The kinetic constants which control the aggregation processes when the electrical repulsion disappears
were estimated by both techniques at different particle concentration and wavelength in order to establish the experimental
conditions which provided reliable and similar values for the coagulation rate constant. Both experimental techniques (turbidity
and nephelometry) and two ways of fitting the data have been used with both latexes. For the first method, the initial slope
of turbidity or total scattered intensity versus time curves were used to calculate the kinetic constants. In the second method,
the whole turbidity or total scattered intensity versus time curves were fitted and the kinetic constants calculated. An unambiguous
experimental value for the doublet rate constant in diffusion conditions is obtained by turbidity and nephelometry techniques.
By nephelometry both data treatments have permitted a distinction between the doublet rate constant and the global rate constant
in diffusion conditions.
Received: 2 June 1997 Accepted: 14 August 1997 相似文献
13.
建立了含不同亲疏水粒子比的双亲性无规共聚物粗粒化模型. 采用耗散粒子动力学方法模拟了两亲性无规共聚物选择性溶剂自组装球形胶束表面的亲水性能. 模拟结果表明, 无规共聚物在选择性溶剂中自组装得到实心球形胶束, 球形胶束表面的亲水性与聚合物链亲水粒子含量、溶剂的选择性有关. 随着聚合物链所含亲水粒子增加, 球形胶束表面的亲水性增强. 球形胶束表面的亲水性随着疏水粒子与溶剂粒子间的排斥参数增大而增强, 模拟结果与实验结论一致. 该模拟方法给出的胶束微结构信息可以为双亲无规共聚物分子设计及自组装双亲胶束制备提供一定的理论指导. 相似文献
14.
New polymer latexes bearing saccharide moieties on the particle surface were synthesized by using a water‐soluble sugar monomer, such as 1‐deoxy‐1‐methacryl‐amido‐D ‐glucitol, (MAG). All the latexes were prepared by a two‐stage emulsion polymerization technique. In the first step, the core was prepared with butyl acrylate (BA) and styrene (St). In the second step, the seed latex was polymerized with ethyl acrylate (EA) and MAG. The influence of a bifunctional monomer such as allyl methacrylate (ALMA), introduced at various concentrations, on the final latexes morphologies and properties was investigated. It was found that the latex particles exhibit a core‐shell structure. The mass balance of MAG showed that the main part of the sugar moiety is on the shell layer. The molecular properties, such as structure, composition, and molecular weight, were determined by elemental analysis, 1H‐ and 13C‐NMR spectroscopy. Colloidal (particle size and their distributions), thermal, and rheological properties were also studied. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
15.
A. A. Rakhnyanskaya I. D. Pebalk V. N. Orlov I. A. Gritskova N. I. Prokopov A. A. Yaroslavov 《Polymer Science Series A》2010,52(5):483-489
The complexation of anionic latex particles with two series of cationic copolymers is studied. The copolymers of the first
series contain cationic and electroneutral (zwitter ion) hydrophilic units. The electrostatic adsorption of these copolymers
on the surface of latex particles is accompanied by the formation of multiple salt bridges between cationic copolymer units
and surface anionic groups. The dependence of ultimate adsorption on the molar fraction of cationic groups in copolymer α
is described by a bell-shaped curve with a maximum at α = 0.05−0.10 and a long horizontal portion at α > 0.24. In terms of
the adsorption theory of polyampholytes, such a pattern of the adsorption curve results from the compromise between the attraction
of polymer chains to the surface induced by their polarization in the electric field of particles and the repulsion of like
charged macromolecular units. The stability of complexes with the copolymers of the first series in water-salt media increases
with an increase in α. The copolymers of the second series contain cationic and hydrophobic units. In this case, an increase
in α is accompanied by a decrease in the amount of the adsorbed polymer throughout the studied α range (0.24–1). The complexes
are stabilized not only via electrostatic interactions but also via hydrophobic interactions. A decrease in α decreases the
role of electrostatics in stabilization of the complexes; however, this effect is compensated for by an increase in the number
of hydrophobic contacts. This allows the stability of complexes to be preserved in concentrated water-salt solutions. The
results of this study indicate that the stability of interfacial layers with the participation of cationic copolymers can
be changed in a wide range by varying the ratio of ionic and electroneutral (hydrophilic or hydrophobic) comonomers in macromolecules. 相似文献
16.
New approach to the synthesis of star-shaped polymers based on calix[8]arene with amphiphilic arms of nonionogenic nature
is described. The ionophore properties of the resulting polymer with respect to ions of alkali metals, europium, and uranium
were studied by an example of a polymer containing residues of ω-cetyloligoethylene oxide as arms. 相似文献
17.
Hydrophilic magnetic polymer latexes. 1. Adsorption of magnetic iron oxide nanoparticles onto various cationic latexes 总被引:5,自引:0,他引:5
With a view to preparing monosized hydrophilic functional magnetic latex particles based on a two-step strategy using anionic
iron oxide and cationic polymer latexes, the adsorption step was systematically investigated for a better control of the subsequent
encapsulation step. The iron oxide nanoparticles were first obtained according to the classical precipitation method of ferric
and ferrous chloride salt using a concentrated sodium hydroxide solution, whereas the polystyrene (PS), P(S/N-isopropylacrylamide (NIPAM)) core–shell and PNIPAM latexes were produced via emulsion and precipitation polymerizations,
respectively. The polymer and inorganic colloids were then characterised. The adsorption of iron oxide nanoparticles onto
the three types of polymer latexes via electrostatic interaction was studied as a function of iron oxide particle concentration,
charge density and the cross-linking density of the hydrophilic layer. The maximum amounts of magnetic nanoparticles adsorbed
onto the various latexes were found to increase in the following order: PS < P(S/NIPAM) < P(NIPAM). This significant difference
is discussed by taking into account the charge distribution in the hydrogel layer and diffusion phenomena inside the cross-linked
hydrophilic shell.
Received: 28 December 1998 Accepted in revised form: 15 April 1999 相似文献
18.
E. V. Zolotukhina T. A. Kravchenko 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(5):813-817
The influence of solution pH on H+-Cu2+ exchange equilibrium was studied for the disperse copper- KU-23 (15/100 S) macroporous strongly acid sulfocation exchanger
nanocomposite. In dilute solutions of copper(II) sulfate in weakly acid media (pH 3–6), ion exchange limitation is related
to the consumption of hydrogen counterions and the formation of copper counterions in a side reaction between copper particles
and impurity oxygen. The concentration of hydrogen counterions in the nanocomposite is replenished as pH decreases because
of their sorption from solution together with copper ions.
Original Russian Text ? E.V. Zolotukhina, T.A. Kravchenko, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No.
5, pp. 934–938. 相似文献
19.
Potentiometric sensors with plasticized polymer membranes based on tetraalkylammonium organic ion exchangers and silver(I)
complexes with ampicillin, oxacillin, and cefazolin are proposed for the quantification of antibiotics in model mixtures.
The quantitative parameters of complex species of silver with β-lactam antibiotics (β-lac) are established. The complexes
(β-lac)2Ag are shown applicable as electroactive components of membranes of potentiometric sensors with tetraalkylammonium cations
as counterions. For the information on potentiometric selectivity coefficients and the parameters of cross-sensitivity of
sensors in solutions of β-lactam antibiotics they might be used in multisensor systems of the electronic tongue type. The
analytical signals are processed by the method of neural network. The average relative error of the individual quantification
of β-lactam antibiotics in three-component model mixtures was 4–6%. 相似文献
20.
Hiroshi Kamitakahara Kaoru Murata-Hirai Yoshimasa Tanaka 《Cellulose (London, England)》2012,19(1):171-187
Bioimaging is a key to understanding immune responses, cell differentiation, and development. Quantum dots (QDs) conjugated
with monoclonal antibodies and other biomolecules are currently utilized for flow cytometry and immunohistochemistry, but
monoclonal antibody–QD complexes are of limited use when cell surface markers are not available. In this study, we synthesized
novel amphiphilic blockwise alkylated tetrasaccharides and developed a simple method for labeling a wide variety of live cells
with organic QDs encapsulated with these carbohydrates. The novel amphiphilic blockwise alkylated tetrasaccharides were as
follows: methyl β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-d-glucopyranoside (1), methyl β-d-galactopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-d-glucopyranoside (2), ethyl β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-ethyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-ethyl-d-glucopyranoside, (3), and ethyl β-d-galactopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-ethyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-ethyl-d-glucopyranoside (4). The newly synthesized blockwise alkylated tetrasaccharides spontaneously assembled into micelle-like particles, in which
the hydrophobic moiety of the blockwise alkylated tetrasaccharides played an important role. They were less toxic to human
cells than octyl β-d-glucopyranoside, a commonly used amphiphilic glucoside. Flow cytometry and confocal laser scanning microscopy revealed that
the blockwise alkylated tetrasaccharide–organic QD complexes were stably attached to live cells. The affinity of compounds
1 and 2 to the live cell surface was slightly higher than that of compounds 3 and 4. Because the preparation of these carbohydrate–QD
complexes is simple and does not require sophisticated equipment, and because the complexes can be autonomously attached to
a wide spectrum of cell lines, they can be used as cell labeling reagents in biomedical studies. 相似文献