Papers Published

  1. Kaholek, Marian and Lee, Woo-Kyung and Feng, Jianxin and Lamattina, Bruce and Dyer, Daniel J. and Zauscher, Stefan, Weak polyelectrolyte brush arrays fabricated by combining electron-beam lithography with surface-initiated photopolymerization, Chemistry of Materials, vol. 18 no. 16 (2006), pp. 3660 - 3664 [cm060276r] .
    (last updated on 2007/04/06)

    We present a simple "top-down/bottom-up" strategy to fabricate nano- and micropatterned polymer brush arrays composed of pH- and salt-sensitive, weak polyelectrolyte copolymers [poly(N-isopropy-lacrylamide-co- methacrylic acid, 3:1, poly (NIPAAM-co-MAA)]. In our approach, a silicon surface is first patterned with gold, using "lift-off' electron-beam lithography ("top-down"), and the resulting pattern is then amplified by surface-initiated photopolymerization by conventional, UV-light-induced free radical polymerization ("bottom-up") from an immobilized 2,2 prime -azobisisobutyronitrile (AIBN) type initiator. The use of pH- and ionic-strength-sensitive comonomers in the copolymer brush enables large, externally triggered conformational changes of the micro- and nanopatterned polymer brushes. We observed that the height of nanopatterned ionized polymer brushes increases with increasing feature size of the pattern. The design and fabrication of surfaces with conformationally switchable, patterned polymeric structures is important for sensing and actuation applications on the micro- and nanoscales. © 2006 American Chemical Society.

    Polyelectrolytes;Electron beam lithography;Photopolymerization;pH effects;Salts;Ultraviolet radiation;Free radical polymerization;Initiators (chemical);Ionic strength;