Dynamics of Block Copolymer Micelles Revealed by X-Ray Intensity Fluctuation Spectroscopy

1997 ◽  
Vol 78 (7) ◽  
pp. 1275-1278 ◽  
Author(s):  
S. G. J. Mochrie ◽  
A. M. Mayes ◽  
A. R. Sandy ◽  
M. Sutton ◽  
S. Brauer ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Intensity Fluctuation ◽  
X Ray ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles

scholarly journals Structure of PEP–PEO block copolymer micelles: exploiting the complementarity of small-angle X-ray scattering and static light scattering

2011 ◽  
Vol 44 (3) ◽  
pp. 473-482 ◽  
Author(s):  
Grethe Vestergaard Jensen ◽  
Qing Shi ◽  
María J. Hernansanz ◽  
Cristiano L. P. Oliveira ◽  
G. Roshan Deen ◽  
...  
Keyword(s):  
Light Scattering ◽  
Block Copolymer ◽  
Small Angle ◽  
Static Light Scattering ◽  
Length Scales ◽  
X Ray ◽  
X Ray Scattering ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Poly Ethylene

The structure of large block copolymer micelles is traditionally determined by small-angle neutron scattering (SANS), covering a large range of scattering vectors and employing contrast variation to determine the overall micelle morphology as well as the internal structure on shorter length scales. The present work shows that the same information can be obtained by combining static light scattering (SLS) and small-angle X-ray scattering (SAXS), which provide information on, respectively, large and short length scales. Micelles of a series of block copolymers of poly(ethylene propylene)-b-poly(ethylene oxide) (PEP–PEO) in a 70% ethanol solution are investigated. The polymers have identical PEP blocks of 5.0 kDa and varying PEO blocks of 2.8–49 kDa. The SLS contrasts of PEP and PEO are similar, providing a homogeneous contrast, making SLS ideal for determining the overall micelle morphology. The SAXS contrasts of the two components are very different, allowing for resolution of the internal micelle structure. A core–shell model with a PEP core and PEO corona is fitted simultaneously to the SAXS and SLS data using the different contrasts of the two blocks for each technique. With increasing PEO molecular weight, a transition from cylindrical to spherical micelles is observed. This transition cannot be identified from the SAXS data alone, but only from the SLS data.

Liquid Crystalline Phase Behavior of Well-Defined Cylindrical Block Copolymer Micelles Using Synchrotron Small-Angle X-ray Scattering

2015 ◽  
Vol 48 (5) ◽  
pp. 1579-1591 ◽  
Author(s):  
Dominic W. Hayward ◽  
Joe B. Gilroy ◽  
Paul A. Rupar ◽  
Laurent Chabanne ◽  
Claire Pizzey ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Phase Behavior ◽  
Small Angle ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
X Ray ◽  
X Ray Scattering ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Cylindrical Block

Styrene/butadiene block copolymer micelles in heptane

1985 ◽  
Vol 63 (1) ◽  
pp. 249-252 ◽  
Author(s):  
T. L. Bluhm ◽  
M. D. Whitmore
Keyword(s):  
Block Copolymer ◽  
Radius Of Gyration ◽  
X Ray ◽  
X Ray Scattering ◽  
Micelle Core ◽  
Theoretical Predictions ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Styrene Butadiene ◽  
Good Agreement

The radius of gyration of poly(styrene-b-butadiene) block copolymer micelles in n-heptane is measured by small angle X-ray scattering (SAXS). The results are compared with theoretical predictions, and good agreement is found, particularly for the appropriate scaling relations. It is argued that the radius of gyration of the micelles depends on both the molecular weight and the composition of the copolymers. The dominant factors which determine the micelle core and corona dimensions are identified.

Structural Analysis of Bottlebrush Block Copolymer Micelles Using Small-Angle X-ray Scattering

2020 ◽  
Vol 9 (9) ◽  
pp. 1261-1266
Author(s):  
Seyoung Kim ◽  
Yunshik Cho ◽  
Jee Hyun Kim ◽  
Sanghoon Song ◽  
Jeewoo Lim ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Block Copolymer ◽  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Ray Scattering

The Morphology of Block Copolymer Micelles in Supercritical Carbon Dioxide by Small-Angle Neutron and X-ray Scattering

1997 ◽  
Vol 30 (5) ◽  
pp. 690-695 ◽  
Author(s):  
J. D. Londono ◽  
R. Dharmapurikar ◽  
H. D. Cochran ◽  
G. D. Wignall ◽  
J. B. McClain ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Block Copolymer ◽  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Environmentally Responsible ◽  
Theoretical Predictions ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Ray Scattering

Above its critical point, carbon dioxide forms a super-critical fluid, which promises to be an environmentally responsible replacement for the organic solvents traditionally used in polymerizations. Many lipophilic polymers such as polystyrene (PS) are insoluble in CO2, though polymerizations may be accomplished via the use of PS-fluoropolymer stabilizers, which act as emulsifying agents. Small-angle neutron and X-ray scattering have been used to show that these molecules form micelles with a CO2-phobic PS core and a CO2-philic fluoropolymer corona. When the PS block was fixed in length and the fluorinated corona block was varied, the number of block copolymer molecules per micelle (six to seven) remained constant. Thus, the coronal block molecular weight exerts negligible influence on the aggregation number, in accordance with the theoretical predictions of Halperin, Tirrell & Lodge [Adv. Polym. Sci. (1992), 100, 31–46]. These observations are relevant to understanding the mechanisms of micellization and solubilization in supercritical fluids.

β-lactam Functionalized Poly(isoprene-b-ethylene oxide) Amphiphilic Block Copolymer Micelles as a New Nanocarrier System for Curcumin

2010 ◽  
Vol 6 (3) ◽  
pp. 277-284 ◽  
Author(s):  
Konstantinos Gardikis ◽  
Konstantinos Dimas ◽  
Aristidis Georgopoulos ◽  
Eleni Kaditi ◽  
Stergios Pispas ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Ethylene Oxide ◽  
Amphiphilic Block Copolymer ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles

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.

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