INVESTIGADORES
TAGLIAZUCCHI Mario Eugenio
congresos y reuniones científicas
Título:
Molecular modeling of self-organized polyelectrolyte end-grafted layers
Autor/es:
MARIO TAGLIAZUCCHI; MÓNICA OLVERA DE LA CRUZ; IGAL SZLEIFER
Lugar:
Beer Sheva & Ein-Gedi
Reunión:
Workshop; The 9 th Stadler Minerva student workshop; 2011
Institución organizadora:
Reimund Stadler Minerva Center for Mesoscale Macromolecular Engineering
Resumen:
Responsive materials embrace several
kinds of bulk and surface systems that can alter their structure, behavior or
physical properties as a response to a change in their chemical or physical
environment. We use a molecular theory to study polyelectrolyte and redox
polyelectrolyte end grafted layers, explicitly including the competition
between different physical and chemical interactions. This competition drives
the self‑organization of the film into aggregates of different morphologies
(some of them previously observed in experiments) such as micelles, stripes,
holes and micelles coexisting with non-aggregated chains. These morphologies
arise because grafted hydrophobic polymers tend to form domains since their
chemical attachment to the surface does not enable macrophase separation. In
polyelectrolytes and redox polyelectrolytes the coupling between chemical
equilibrium (i.e. redox and/or acid base equilibrium), van der Waals
interactions and electrostatic forces affects the morphology of the aggregates
and allows control over surface patterns by bulk pH, electrode potential and
salt concentration. We present here a systematic investigation on the effect of
bulk pH, bulk salt concentration, grafting density and electrode potential on
the morphological behavior. We also show that the local environment within the
grafted film can drastically differ from that in the bulk solution, for example
the local pH inside micellar aggregates may differ by more than 1 unit with
that of the bulk solution. For redox polymers, these local properties have an
impact on the (experimentally accessible) current-potential curves. The picture
that emerges from this study is that the final state of the system cannot be
explained or analyzed in terms of each individual molecular interaction, but it
emerges from their global and highly coupled optimization.