Remotely Controlled Adaptive Surfaces

Thursday, November 11, 2010: 10:30 AM
Grand Ballroom A (Hilton)
Ales Zadrazil and Frantisek Stepanek, Chemical robotics laboratory, ICT Prague, Prague, Czech Republic

Controlled adhesion of particles to substrates is of outmost importance for many engineering applications such as targeted drug delivery or changing particles hydrodynamical properties. Herein we experimentally investigate a thermo-sensitive crosslinked hydrogel based on poly(N-isopropylacrylamide (PNIPAM) as a building block of such adaptive particles. Such hydrogel can exhibit volume transition from swollen to shrunken state at lower critical solution temperature LCST of approximately 32 °C. When hydrogel is incorporated into the particles structure (pores), its temperature-controlled volume change, will affect particles properties, by hydrogels expansion/collapsion from/to pores. In order to effectuate “remote control” of the hydrogel volume change, magnetic nanoparticles (like Fe3O4) were incorporated into hydrogels structure. Upon exposing such composite hydrogel to the alternating magnetic field, the temperature of hydrogel will increase locally and induce a transition from expanded to the collapsed state. SiO2 based porous micropartisles were chosen to be a model substrated. It was shown that hydrogel can reversibly expand/collapse from/into the plexi-glass pores. The effect of pore depth/diameter ratio on the hydrogel volume expanding from the pore was investigated.

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