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Preparation and Characterization of Low Dispersity Anionic Multiresponsive Core–Shell Polymer Nanoparticles
journal contribution
posted on 2016-02-21, 16:01 authored by J. P. Pinheiro, Leila Moura, Remco Fokkink, J. P. S. FarinhaWe prepared anionic multistimuli responsive core–shell
polymer
nanoparticles with very low size dispersity. By using either acrylic
acid (AA) or methacrylic acid (MA) as a comonomer in the poly(N-isopropyl acrylamide) (PNIPAM) shell, we are able to change
the distribution of negative charges in the nanoparticle shell. The
particle size, volume phase transition temperature, and aggregation
state can be modulated using temperature, pH, or ionic strength, providing
a very versatile platform for applications in sensors, medical diagnostics,
environmental remediation, etc. The nanoparticles have a glassy poly(methyl
methacrylate) (PMMA) core of ca. 40 nm radius and a cross-linked PNIPAM
anionic shell with either AA or MA comonomers. The particles, p(N-AA)
and p(MA-N), respectively, have the same total charge but different
charge distributions. While the p(MA-N) particles have the negative
charges preferentially distributed toward the inner shell, in the
case of the p(N-AA) particles the charge extends more to the particle
outer shell. The volume phase transition temperature (TVPT) of the particles is affected by the charge distribution
and can be fine-tuned by controlling the electrostatic repulsion on
the particle shell (using pH and ionic strength). By suppressing the
particle charge we can also induce temperature-driven particle aggregation.