Poly(dimethylsiloxane) stamps for microcontact printing with polar inks, wh
ich no longer need to be reactivated after each printing step, are revealed
. The silicone surface is modified by linking a hydrophilic polyethylene gl
ycol chain to SiOH groups created on the surface of the stamp. While stamps
that are oxidized conventionally become useless 3 h after their preparatio
n (Figure top), the PEG-modified stamps can still print high-quality patter
ns after 20 days (Figure bottom).