Letter pubs.acs.org/macroletters
Temperature-Controlled Diffusion in PNIPAM-Modified Silica Inverse Opals Jing Xie,† Mikheil Doroshenko,† Ulrich Jonas,‡ Hans-Jürgen Butt,† and Kaloian Koynov*,† †
Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany Macromolecular Chemistry, Department Chemistry−Biology, University of Siegen, Adolf-Reichwein-Strasse 2, AR-G 213, D-57076 Siegen, Germany
‡
S Supporting Information *
ABSTRACT: We report a new strategy for the preparation of well-defined and mechanically stable porous nanostructures with tunable porosity. Silica inverse opals, which are known as a model system for a porous periodic nanostructure, were grafted with brushes of the thermoresponsive poly(N-isopropylacrylamide) grown via atom transfer radical polymerization. By tuning the temperature, the swelling state of the brush layer is reversibly altered, and with this we were able to control the overall porosity of the system and, thus, the mobility of small penetrants. Fluorescence correlation spectroscopy, a method combining single molecule sensitivity with small probing volume (
