Structure of Polyelectrolyte Block Copolymer Micelles

Abstract

The structure of charged spherical block copolymer micelles in aqueous solution was investigated with static and dynamic light scattering, small-angle neutron scattering, and cryo-electron microscopy as a function of added salt. At low added salt concentration the polyelectrolyte shell has typical features of an osmotic brush. If the added salt concentration exceeds the intrinsic ionic strength of the polyelectrolyte shell, the micellar aggregation number increases due to screening of the repulsive interaction between polyelectrolyte chains (salted brush). The relation between shell ionic strength and added salt concentration follows a simple Donnan equilibrium. The combination of methods reveals that the polyelectrolyte shell is phase-separated into a dense interior and a dilute outer domain.

Characterization of sodium poly(4-styrenesulfonate)-grafted polymer fine particles synthesized by core-cross-linking of block copolymer micelles

“…R h -R c corresponds to the brush thickness of the polySSNa-grafted particle. The slope of the plot in the region between 0.01 and 0.2 M is approximately À0.12, which agrees well with the reported value for the salt concentration dependence of the shell thickness for polySScontaining micelles (À0.11 to À0.14) [30,31]. These results indicate that the graft chains stretched by the electrostatic repulsions shrank due to the screening effect of the added salts.…”

Thermoresponsive behavior of micellar aggregates from end-functionalized PnBA-b-PNIPAM-COOH block copolymers and their complexes with lysozyme

“…This supports the hypothesis that the hydrophilic-hydrophobic transition of PNIPAM creates particles with a hard hydrophobic interior and soft hydrophilic charged surface. 10 Å are common for well-defined core-shell objects in solution 22,27 . The high regime scales roughly as and hence cannot be followed by the spherically 12 symmetric model which scales as .…”

Effective short-range Coulomb correction to model the aggregation behavior of ionic surfactants

“…As a consequence, one can conclude that the charge density distribution in the counterions and the permittivity of the hydrophobic micellar core have a very weak impact on the CMC, which is adequately predicted by the traditional form of the Coulomb potential provided in Eq. (2). In other words, a simple CG model neglecting key physico-chemical details of a micellar solution of ionic surfactants is still able to provide a good estimate of the CMC as long as the effective interactions between tail beads, T T , is consistently set.…”

“…The structural features of these clusters, such as size, shape and packing, are deeply related to some key physico-chemical parameters (temperature, pH, salt concentration, etc.) [1][2][3][4][5][6][7][8] as well as to the molecular architecture of their building blocks [9]. Their spontaneous aggregation or self-assembly, being rather recurrent in soft matter systems, is driven by a complex competition between enthalpic and entropic forces, which might be dramatically altered by almost intangible thermal fluctuations of few k B T , with T the absolute temperature and k B 1.38 × 10 −23 J K −1 the Boltzmann's constant.…”