IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Organic Films and Devices Thursday Sessions
       Session OF+SS-ThP

Paper OF+SS-ThP5
Surface Plasmon Resonance Techniques for In Situ Detection of LCST Behavior on Surface-Grafted Polymer Films

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Molecular Aspects of Organic Films Poster Session
Presenter: S. Mendez, University of New Mexico
Authors: S. Mendez, University of New Mexico
S. Balamurugan, University of New Mexico
L.K. Ista, University of New Mexico
G.P. Lopez, University of New Mexico
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Thin films of the temperature responsive polymer, poly(N-isopropylacrylamide) (PNIPAAM), were polymerized in situ on azo-initiator derivatized self-assembled monolayers (SAMs). Carboxylic acid and methyl-terminated alkanethiols were used to form mixed component SAMs on gold substrates. Reaction of the COOH moieties with Woodwards reagent K and an amine containing azo-initiator resulted in immobilization of the initiator on the surface. PNIPAAM was then grown from the surface upon exposure of the surfaces to heat and monomer solution. Varying the concentration of COOH-thiolate within the original SAM allowed us to control the surface coverage of the polymer. Surface plasmon resonance (SPR) was used to detect the lower critical solubility temperature (LCST) transition of these surface-grafted polymers by taking advantage of a difference in both thickness and refractive index of the polymers in their relaxed (low temperature) and collapsed (high temperature) states. Realtime, in situ reflectance measurements of the PNIPAAM films immersed in water were taken as the temperature of the samples was raised. The effect of surface coverage on the position and degree of the transition was also examined.