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Papers Published

  1. Hyun, Jinho and Chilkoti, Ashutosh, Surface-initiated free radical polymerization of polystyrene micropatterns on a self-assembled monolayer on gold, Macromolecules, vol. 34 no. 16 (2001), pp. 5644 - 5652 [ma002125u] .
    (last updated on 2007/04/12)

    Abstract:
    We describe the in situ synthesis of nanometer thick films of polystyrene (PS) on a self-assembled monolayer (SAM) on gold by surface-initiated free radical polymerization and further demonstrate that three-dimensional polymer structures with micrometer lateral resolution and nanometer vertical resolution can be fabricated by combining microcontact printing (μCP) with surface-initiated polymerization (SIP). We implemented SIP onto a COOH-terminated SAM on gold using a sequential approach to couple an amine-terminated free radical initiator to the terminal COOH groups presented by the SAM, followed by free radical polymerization of styrene. Each step of SIP was characterized by X-ray photoelectron spectroscopy and ellipsometry, and the PS film and micropattern were also characterized by atomic force microscopy. We typically Obtained PS films with a thickness of 10-20 nm for a polymerization time of 12-24 h and with a root-mean-square roughness of [less-than or equal to] 0.5 nm. PS micropatterns were also successfully fabricated by reactive μCP of the initiator onto a COOH-terminated SAM, followed by SIP of styrene. We also demonstrate two potential applications of SIP in biomaterials research: (1) label-free, real-time monitoring of protein adsorption on polymers by surface plasmon resonance (SPR) on nanometer thick homogeneous polymer films fabricated on a SAM on gold and (2) patterning cells on micropatterned polymers fabricated by combining μCP and SIP.

    Keywords:
    Plastic films;Free radical polymerization;Thick films;Self assembly;Surface phenomena;Gold;Initiators (chemical);Proteins;Adsorption;Monolayers;Surface roughness;Surface plasmon resonance;X ray photoelectron spectroscopy;Atomic force microscopy;Ellipsometry;