Electrostatic and Association Phenomena in Aggregates of Polymers and Micelles

Abstract

An automatic, continuous-mixing technique is introduced to measure light scattering and viscosity simultaneously over a wide range of solute concentrations in multicomponent systems. Behavior along arbitrary curves in component coordinates can be monitored. This technique is used to investigate the association and electrostatically based excluded-volume interactions that arise in solutions of interacting neutral polymers and charged micelles. In this study, the ionic surfactant sodium dodecyl sulfate (SDS) and a neutral polymer poly(vinylpyrrolidone) (PVP) were chosen. The SDS confers pseudopolyelectrolyte properties on the polymer/micelle aggregates (PSA), such as electrostatically enhanced second and third virial coefficients A2 and A3, respectively. The presence of a large A3 is directly observed as a well-defined maximum in scattering intensity versus [PVP] under saturating SDS conditions. The electrostatically enhanced three-body effects represented by A3 in light scattering are nearly 3 orders of magnitude greater than the corresponding three-body terms in viscosity. A viscosity effect reminiscent of the electroviscous effect seen for linear polyelectrolytes is observed, but it occurs under very different PSA concentration and solution ionic strength conditions.

Adsorption of copolymers aggregates: From kinetics to adsorbed layer structure

“…Copolymer solutions were also characterized via static light scattering, using the Automatic Continuous Mixing (ACM) approach [45,46]. A Shimadzu gradient pump was used to create a continuous ramp of copolymer concentration, and the scattering intensity of this flowing solution was measured simultaneously at seven angles using a Brookhaven Instruments Corporation BI-MwA.…”

Online monitoring of diallyldimethylammonium chloride polymerization

“…A 2 values for the correction term in Eq . were determined by seperate measurements and are given in Table are used . Hence determination of R θ and c at every point in time allows weight average molecular weight to be computed from Eq .…”

Automatic continuous online monitoring of polymerization reactions (ACOMP)

“…Gradient pumps are used to create selected paths in the composition space of the solution, and light scattering and viscosity data are gathered over the path, and the RI and/or UV detectors are used to compute the solute concentrations at each point of the path. Examples include determination of effects of added electrolyte on polyelectrolyte dimensions, interactions and hydrodynamics,32, 33 ion‐specific effects and interactions of surfactants, polymers, aromatic molecules and electrolytes 34. Figure 6 gives an example of ACM data showing the effect of increasing electrolyte (NaCl) concentration on the LS and viscosity of a highly charged, linear polyelectrolyte, sodium hyaluronate (HA).…”