K. Kratz et al., Effect of connectivity and charge density on the swelling and local structural and dynamic properties of colloidal PNIPAM microgels, BER BUN GES, 102(11), 1998, pp. 1603-1608
Citations number
25
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
BERICHTE DER BUNSEN-GESELLSCHAFT-PHYSICAL CHEMISTRY CHEMICAL PHYSICS
The structural and dynamic properties of thermosensitive neutral and partia
lly charged colloidal microgels of poly(N-isopropylacrylamide-co-acrylic ac
id) (PNIPAM/AAc) have been investigated by neutron and light scattering tec
hniques. Introduction of cross-linker induces topological constraints into
the polymer network, and hence reduces the swelling capability of the parti
cles as expressed in the variation of their hydrodynamic radii. Small-angle
neutron scattering experiments reveal that below the transition temperatur
e the inhomogeneous structure of the microgel consists of local solid-like
frozen regions and solution-like regions where the polymer chain behaves as
in semidilute polymer solution. The temperature-induced collapse leads to
a strongly segregated micro-phase separated particle. The swelling of charg
ed microgels is determined by their charge density, controlled through the
amount of acrylic acid comonomer, the pH, and the salt concentration.