Copolymer Micelles with Polyelectrolyte Shell in Aqueous Media. A Mean-Field Study

2006 ◽  
Vol 71 (5) ◽  
pp. 756-768 ◽  
Author(s):  
Karel Jelínek ◽  
Filip Uhlík ◽  
Zuzana Limpouchová ◽  
Pavel Matějíček ◽  
Karel Procházka
Keyword(s):  
Aqueous Media ◽  
Excitation Energy Transfer ◽  
Mean Field ◽  
Hydrophobically Modified ◽  
Small Influence ◽  
Covalently Bonded ◽  
Self Consistent Field ◽  
Copolymer Micelles ◽  
And Behavior ◽  
Scf Calculations

The multimolecular micelles formed by polystyrene-block-poly(methacrylic acid) (PS-PMA) copolymer and by hydrophobically modified PS-PMA copolymer with naphthalene and anthracene (PS-N-PMA-A) were studied by self-consistent field (SCF) calculations in aqueous media. The labeling with covalently bonded naphthalene between PS and PMA blocks and with anthracene at the free end of PMA blocks, which is suitable for experimental nonradiative excitation energy transfer (NRET) studies of PS-N-PMA-A micelles, modifies the structure of micellar shell. The study was aimed at understanding structure and behavior of micelles at different pH and ionic strength. The results show that the presence of hydrophobic tags has only a small influence on the overall structure of micelles but it strongly affects the distribution of PMA free ends. The hydrophobic labels (anthracenes) try to return into the shell and their certain fraction is localized close to the core/shell interface, which causes a fairly high NRET efficiency. The calculated and experimentally measured NRET efficiency were compared; their trends are reasonable at the semiquantitative level.

Hydrophobically Modified Amphiphilic Block Copolymer Micelles in Non-Aqueous Polar Solvents. Fluorometric, Light Scattering and Computer-Based Monte Carlo Study

2002 ◽  
Vol 67 (5) ◽  
pp. 531-556 ◽  
Author(s):  
Pavel Matějíček ◽  
Filip Uhlík ◽  
Zuzana Limpouchová ◽  
Karel Procházka ◽  
Zdeněk Tuzar ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Light Scattering ◽  
Aqueous Media ◽  
Excitation Energy Transfer ◽  
Monte Carlo Study ◽  
Fluorescence Decay ◽  
Model Systems ◽  
Interfacial Region ◽  
Hydrophobically Modified ◽  
Rich Mixtures

The micellization behavior of a hydrophobically modified polystyrene-block-poly(methacrylic acid) diblock copolymer, PS-N-PMA-A, tagged with naphthalene between blocks and with anthracene at the end of the PMA block, was studied in 1,4-dioxane-methanol mixtures by light scattering and fluorescence techniques. The behavior of a single-tagged sample, PS-N-PMA, and low-molar-mass analogues was studied for comparison. Methanol-rich mixtures with 1,4-dioxane are strong selective precipitants for PS. Multimolecular micelles with compact PS cores and PMA shells may be prepared indirectly by dialysis from 1,4-dioxane-rich mixtures, or by a slow titration of copolymer solutions in 1,4-dioxane-rich solvents with methanol under vigorous stirring. In tagged micelles, the naphthalene tag is trapped in nonpolar and fairly viscous core/shell interfacial region. In hydrophobically modified PS-N-PMA-A micelles, the hydrophobic anthracene at the ends of PMA blocks tends to avoid the bulk polar solvent and buries in the shell. The distribution of anthracene tags in the shell is a result of the enthalpy-to-entropy interplay. The measurements of direct nonradiative excitation energy transfer were performed to estimate the distribution of anthracene-tagged PMA ends in the shell. The experimental fluorometric data show that anthracene tags penetrate into the inner shell in methanol-rich solvents. Monte Carlo simulations were performed on model systems to get reference data for analysis of time-resolved fluorescence decay curves. A comparison of experimental and simulated decays indicates that hydrophobic traps return significantly deep into the shell (although not as deep as in aqueous media). The combined light scattering, fluorometric and computer simulation study shows that the conformational behavior of shell-forming PMA blocks in non-aqueous media is less affected by the presence of nonpolar traps than that in aqueous media.

OPTICAL TRANSITIONS IN A PARABOLIC GaAs/Ga1-xAlxAs SUPERLATTICES

2001 ◽  
Vol 08 (03n04) ◽  
pp. 321-325
Author(s):  
ŞAKIR ERKOÇ ◽  
HATICE KÖKTEN
Keyword(s):  
Transition Matrix ◽  
Optical Transition ◽  
Matrix Elements ◽  
Electron States ◽  
Parabolic Potential ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Transition Matrix Elements ◽  
Scf Calculations

We have performed self-consistent field (SCF) calculations of the electronic structure of GaAs/Ga 1-x Al x As superlattices with parabolic potential profile within the effective mass theory. We have calculated the optical transition matrix elements involving transitions from the hole states to the electron states, and we have also computed the oscillator strength matrix elements for the transitions among the electron states.

(Invited) Functionalization and Behavior in Aqueous Media of Silicon Surfaces for Improved Biochemical Sensing

2019 ◽  
Vol 35 (8) ◽  
pp. 101-107
Author(s):  
Jean-Noel Chazalviel ◽  
Philippe Allongue ◽  
Anne Chantal Gouget-Laemmel ◽  
Catherine Henry de Villeneuve ◽  
Anne Moraillon ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Silicon Surfaces ◽  
Biochemical Sensing ◽  
And Behavior

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

scholarly journals Understanding Depletion Induced Like-Charge Attraction from Self-Consistent Field Model

2017 ◽  
Vol 22 (1) ◽  
pp. 95-111 ◽  
Author(s):  
Pei Liu ◽  
Manman Ma ◽  
Zhenli Xu
Keyword(s):  
Mean Field ◽  
Interaction Force ◽  
Systematic Investigation ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Anomalous Feature ◽  
Long Time ◽  
Ionic Size ◽  
Poisson Boltzmann ◽  
Force Calculation

AbstractThe interaction force between likely charged particles/surfaces is usually repulsive due to the Coulomb interaction. However, the counterintuitive like-charge attraction in electrolytes has been frequently observed in experiments, which has been theoretically debated for a long time. It is widely known that the mean field Poisson-Boltzmann theory cannot explain and predict this anomalous feature since it ignores many-body properties. In this paper, we develop efficient algorithm and perform the force calculation between two interfaces using a set of self-consistent equations which properly takes into account the electrostatic correlation and the dielectric-boundary effects. By solving the equations and calculating the pressure with the Debye-charging process, we show that the self-consistent equations could be used to study the attraction between like-charge surfaces from weak-coupling to mediate-coupling regimes, and that the attraction is due to the electrostatics-driven entropic force which is significantly enhanced by the dielectric depletion of mobile ions. A systematic investigation shows that the interaction forces can be tuned by material permittivity, ionic size and valence, and salt concentration, and that the like-charge attraction exists only for specific regime of these parameters.

Sign in / Sign up

Export Citation Format

Share Document