ma8b01019_si_002.pdf (8.23 MB)
Preparation of Polymer Brush Grafted Anionic or Cationic Silica Nanoparticles: Systematic Variation of the Polymer Shell
journal contribution
posted on 2018-08-29, 17:53 authored by Marek Sokolowski, Christoph Bartsch, Vivian J. Spiering, Sylvain Prévost, Marie-Sousai Appavou, Ralf Schweins, Michael GradzielskiPolymer
brush grafted anionic SiO2@PMAA (poly(methacrylic
acid)) and cationic SiO2@PDMAEMA (poly(2-(dimethylamino)ethyl
methacrylate)) inorganic/polymer hybrid nanoparticles with different
core radii (dNP = 50–140 nm) and
different amounts of attached polymer were synthesized via surface-initiated
atomic transfer radical polymerization (ATRP). To avoid irreversible
aggregation, a three-step surface modification had to be employed,
thereby keeping the nanoparticles always dispersed. For SiO2@PMAA the shell thickness changes with the monomer concentration,
while for SiO2@PDMAEMA the grafting density was changed
by monomer concentration and the shell thickness remained constant.
We assume that the control over the grafting density relies on the
nature of the complexation potential of the PDMAEMA. The structural
characterization of the polymer grafted SiO2-NPs was done
in detail by different scattering methods combined with thermogravimetric
analysis, and details of the brush characteristics are obtained by
small-angle neutron scattering (SANS). With this approach we were
able to produce silica nanoparticles with anionic and cationic polymer
shells, where the softness of the NPs can be controlled by the amount
of polymer, which are pH-responsive and colloidally stable over a
large pH range.