Block Copolymer Micelles in Aqueous Media

1993 ◽  
Vol 58 (10) ◽  
pp. 2362-2369 ◽  
Author(s):  
Zdeněk Tuzar ◽  
Pavel Kratochvíl ◽  
Karel Procházka ◽  
Petr Munk
Keyword(s):  
Methacrylic Acid ◽  
Dynamic Equilibrium ◽  
Aqueous Media ◽  
Sedimentation Velocity ◽  
Micellar System ◽  
Micellar Systems ◽  
Large Particles ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Rich Mixtures

Micellization of di- and triblock copolymers, poly(methacrylic acid)-block-polystyrene and poly(methacrylic acid)-block-polystyrene-block-poly(methacrylic acid), varying in molecular weight and composition, has been studied by static and dynamic light scattering, and sedimentation velocity. Micelles with polystyrene cores were prepared in water-dioxane mixtures, rich in dioxane, and transferred into water-rich mixtures, water, and aqueous buffers via stepwise dialysis. It has been shown that, in dioxane-rich mixtures, the micellar system was in dynamic equilibrium, while in water-rich solvents, water, and aqueous buffers the micellization equilibrium was frozen and micelles behaved like autonomus particles. Under certain conditions, micelles were accompanied by independent large particles. This phenomenon, known from other micellar systems as an "anomalous micellization", is discussed.

Study of Sedimentation Velocity of Block Copolymer Micelles

1993 ◽  
Vol 58 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Minmin Tian ◽  
C. Ramireddy ◽  
Stephen E. Webber ◽  
Petr Munk
Keyword(s):  
Block Copolymer ◽  
Methacrylic Acid ◽  
Mixed Solvent ◽  
Hard Spheres ◽  
Sedimentation Velocity ◽  
Hydrodynamic Coefficient ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Size Heterogeneity ◽  
Good Agreement

No anomalies were observed during the measurement of sedimentation coefficients of block copolymer micelles formed by copolymers of styrene and methacrylic acid in a mixed solvent; 80 vol.% of dioxane and 20 vol.% of water. The shapes of the sedimenting boundaries suggest that the size heterogeneity of the micelles is small. Linear relations between 1/s and c were obtained. The value of the hydrodynamic coefficient κ was between 2 and 4 in a good agreement with the value 2.75 or 2.86 that was obtained by combining Burgers' or Fixman's values of the coefficient of the concentration dependence kvs for hard spheres with Einstein's value of [η] for spheres.

Donnan Equilibria in Polymeric Micellar Systems with Weak Polyelectrolyte Shells: The Lowering of the pH Value

1997 ◽  
Vol 62 (11) ◽  
pp. 1730-1736 ◽  
Author(s):  
Petr Munk ◽  
Zdeněk Tuzar ◽  
Karel Procházka
Keyword(s):  
Ionic Strength ◽  
Block Copolymer ◽  
Ph Value ◽  
Electrolyte Solutions ◽  
Hydrogen Ions ◽  
Micellar Systems ◽  
Weak Electrolytes ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Polyelectrolyte Solutions

When two electrolyte solutions are separated and only some of the ions can cross the boundary, the concentrations of these ions are different on both sides of the boundary. This is the well-known Donnan effect. When weak electrolytes are involved, the imbalance includes also hydrogen ions: there is a difference of pH across the boundary and the dissociation of nondiffusible weak electrolytes is suppressed. The effect is very pronounced when the concentration of the weak electrolyte is high and ionic strength is low. The significance of this phenomenon is discussed for polyelectrolyte solutions, and particularly for block copolymer micelles with weak polyelectrolyte shells. The effect is quite dramatic in the latter case.

A Monte Carlo Study of Flexible Polymer Chain Conformations in Restricted Volumes. I. A Model for Insoluble Blocks Conformations in Swollen Cores of Multimolecular Spherical Block Copolymer Micelles

1993 ◽  
Vol 58 (10) ◽  
pp. 2290-2304 ◽  
Author(s):  
Zuzana Limpouchová ◽  
Karel Procházka
Keyword(s):  
Monte Carlo ◽  
Block Copolymer ◽  
Monte Carlo Study ◽  
Volume Effect ◽  
Micellar Systems ◽  
Flexible Polymer ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Chain Conformations ◽  
Chain Lengths

Monte Carlo simulations of chain conformations in a restricted spherical volume at relatively high densities of segments were performed for various numbers of chains, N, and chain lengths (number of segments), L, on a tetrahedral lattice. All chains are randomly end-tethered to the surface of the sphere. A relatively uniform surface density of the tethered ends is guaranteed in our simulations. A simultaneous self-avoiding walk of all chains creates starting conformations for a subsequent equilibration. A modified algorithm similar to that of Siepmann and Frenkel is used for the equilibration of the chain conformations. In this paper, only a geometrical excluded volume effect of segments is considered. Various structural and conformational characteristics, e.g. segment densities gS(r), free end densities gF(r) as functions of the position in the sphere (a distance from the center), distributions of the tethered-to-free end distances, ρTF(rTF), etc. are calculated and their physical meaning is discussed. The model is suitable for studies of chain conformations is swollen cores of multimolecular block copolymer micelles and for interpretation of non-radiative excitation energy migration in polymeric micellar systems.

Fluorometric and Ultraviolet−Visible Absorption Study of Poly(methacrylic acid) Shells of High-Molar-Mass Block Copolymer Micelles†

Langmuir ◽  
1999 ◽  
Vol 15 (12) ◽  
pp. 4185-4193 ◽  
Author(s):  
Miroslav Štěpánek ◽  
Klára Podhájecká ◽  
Karel Procházka ◽  
Yue Teng ◽  
Stephen E. Webber
Keyword(s):  
Block Copolymer ◽  
Methacrylic Acid ◽  
Molar Mass ◽  
Absorption Study ◽  
Visible Absorption ◽  
High Molar Mass ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles

Fluorometric Studies of the Polyelectrolyte Shell of Block Copolymer Micelles in Aqueous Media

Langmuir ◽  
1999 ◽  
Vol 15 (26) ◽  
pp. 8800-8806 ◽  
Author(s):  
Miroslav Štěpánek ◽  
Karel Procházka
Keyword(s):  
Block Copolymer ◽  
Aqueous Media ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles

Block copolymer micelles in aqueous media

1992 ◽  
Vol 58 (1) ◽  
pp. 195-199 ◽  
Author(s):  
P. Munk ◽  
C. Ramireddy ◽  
M. Tian ◽  
S. E. Webber ◽  
K. Procházka ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Aqueous Media ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles

Study of Sedimentation Velocity of Block Copolymer Micelles

1993 ◽  
Author(s):  
Minmin Tian ◽  
C. Ramireddy ◽  
Stephen E. Webber ◽  
Petr Munk
Keyword(s):  
Block Copolymer ◽  
Sedimentation Velocity ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles
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