Berlin 2005 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 8: SYMPOSIUM: Polymer networks and beyond: From molecular structure to materials and biological functions III

CPP 8.6: Vortrag

Samstag, 5. März 2005, 16:00–16:15, TU C243

Swelling, Elasticity and Spatial Inhomogeneity of Poly(N-isopropylacrylamide)/Clay Nanocomposite Hydrogels — •Jingjing Nie, Binyang Du, and Wilhelm Oppermann — Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld Str. 4, 38678 Clausthal-Zellerfeld, Germany

Hydrogels were prepared by polymerizing N-isopropylacrylamide without any chemical cross-linker in an aqueous dispersion of exfoliated clay particles. The shear modulus of such gels rises in proportion with clay concentration. This seems to indicate that we have a network where the clay particles act as multifunctional cross-links. The influence of clay concentration, monomer concentration, and preparation temperature on macroscopic and structural properties was systematically investigated by mechanical measurements, swelling measurements and static light scattering. Interestingly, the swelling ratio is fairly independent of clay concentration and also of the other parameters varied. This is in contrast to chemically cross-linked networks and may be traced back to a markedly different microstructure. The static light scattering results reveal two correlation lengths, i.e. two types of spatial inhomogeneities. Their dependence on the parameters used to synthesize the networks will be discussed.