Finite-Size Networks from Cylindrical Polyelectrolyte Brushes and Porphyrins

Abstract

We report on the electrostatic self-assembly of negatively charged cylindrical polystyrenesulfonate (NaPSS) brushes and stiff organic counterions of different valency. In particular, the tetravalent cationic porphyrin meso-tetrakis(4-(trimethylammonium)phenyl)porphyrin (TAPP) yielded two new supramolecular architectures that are stable in aqueous solution. The porphyrin binds to the polyelectrolyte brush due to electrostatic and secondary π-π interactions and can further interconnect the brushes to nanoscale networks. In salt solution individual porphyrin-decorated cylindrical brushes were obtained. Structures formed are characterized by UV-vis spectroscopy, atomic force microscopy (AFM), cryo-transmission electron microscopy (cryo-TEM), small-angle neutron scattering (SANS), and dynamic light scattering (DLS). In order to study porphyrin aggregates by DLS, an IR laser setup (λ ) 831.5 nm) was used. The new morphologies have potential as functional structures in molecular electronics and pharmaceutics.

Fluorescent Nanoparticles through Self‐Assembly of Linear Ionenes and Pyrenetetrasulfonate

“…The findings extend other recent results that showed that aggregates of defined size and shape can be obtained when polyelectrolytes with special architectures are used, [54][55][56][57][58][59][60] while this was not the case for more flexible systems with more conformational freedom. [42][43][44][45][46][47][48][49] The present study showed that linear polyelectrolytes with multivalent aromatic counterions can also lead to assemblies of a defined size, but only in certain cases when the polyelectrolyte chain provides certain constraints.…”

“…A detailed consideration of such issues for the case of polyelectrolyte assemblies with cylindrical brushes was recently performed. [57] While the question about how the aggregate size is controlled, is of fundamental interest, the one or the other control may be of advantage for different types of applications. Specifically, kinetically controlled particles are to be expected to be more stable under a wider range of conditions rather than responsive equilibrium structures.…”

“…Recently we could show that this can be achieved using polyelectrolytes of certain architectures in combination with stiff, multivalent, organic counterions. [54][55][56][57][58][59][60] It was found that in this type of ''electrostatic self-assembly'' the interplay of electrostatic interaction between counterion and macroion and additional mutual secondary interaction of the counterions, in particular ''p-p-stacking,'' can yield welldefined nanoassemblies in solution. Association of poly-(amidoamine) (PAMAM) dendrimers with the two isomeric naphthalene dicarboxylic acids resulted in cylindrical and spherical aggregates.…”

Architecture, Assembly, and Emerging Applications of Branched Functional Polyelectrolytes and Poly(ionic liquid)s

“…Not only can CPBs interact with large oppositely charged polyelectrolytes to form different kinds of assemblies, they can also interact with smaller counterions in an interesting way. For example, the tetravalent cationic porphyrin binds to the PSS CPBs due to electrostatic and secondary π-π interactions 78. CPB macromolecules can be further interconnected into nanoscale networks.…”

Polyelectrolyte Stars and Cylindrical Brushes

“…The results are in good agreement with our experimental findings. Moreover, Wegner et al [146] and Gröhn et al [149] studied the influence of the aggregating behavior of polyelectrolytes with multivalent counterions.…”