Macromolecular Rapid Communications, Vol.32, No.6, 523-527, 2011
Association of a Cylindrical Polyelectrolyte Brush with Tetravalent Counterions
Cylindrical poly(styrene sulfonate) brushes were combined with a tetravalent double-DABCO based counterion. With increasing addition of counterion, hydrodynamic radius and radius of gyration decrease and AFM reveals a conformation change from wormlike to curled structures. R-g/R-h changes from 1.3 to 0.9. Above charge stoichiometry, brushes become interconnected into finite size assemblies, which are stable in aqueous solution for charge ratios (ratio of the molar concentration of charged counterion groups to the molar concentration of charged monomer units of the polymer brush) 1 < l < 1.2. They are compact and consist of the brushes in curled (bent) conformation, which is in difference to network-like aggregates from cylindrical poly(styrene sulfonate) brushes with tetravalent porphyrin counterions (Grohn et al. Macromolecules 2009) and to a wormlike-bent conformation-helix transition found for another brush counterion system (Muller et al. Soft Matter 2009).