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# Metal-polymer interfaces: Molecular level synthesis and characterization of a platinum-polystyrene interface and polymer monolayers prepared by the spontaneous adsorption of sulfur - functionalized polystyrene on gold surfaces

#### Abstract

Metal-polymer interfaces were investigated by the synthesis and characterization of two model systems. The first system consisted of a coordinating ligand attached to a clean platinum black surface, which when activated initiated polymerization of monomer. A series of coordinating ligands were investigated and 4-picoline was chosen because it adsorbed irreversibly and perpendicularly, and its pseudo-benzylic hydrogens were acidic and could be removed to form an anionic polymerization initiator. The amount of 4-picoline adsorbed to platinum black was determined by three independent methods: UV-vis spectroscopy, gravimetric and elemental analyses. The platinum-picoline-polystyrene interface was characterized by FTIR spectroscopy and elemental analyses. A control experiment was run in which polystyrene was polymerized anionically in the presence of clean platinum. FTIR identified the polystyrene in the polymer-grafted-platinum sample, while none was observed in the control. The second system investigated consisted of polymer monolayers prepared by the spontaneous adsorption of thiol-terminated polystyrene and polystyrene/poly(propylene sulfide) block copolymers from solution onto glass-supported evaporated gold films. Experiments were performed to determine what control of polymer film thickness could be exercised by changes in molecular weight, concentration, solvent composition and extent of sulfur-functionalization. The monolayers were characterized by various techniques: External reflectance FTIR spectroscopy was used to identify the polymer adsorbed to the gold surface. X-ray photoelectron spectroscopy provided information about the elemental composition of the outer surface. Liquid scintillation counting was used to determine the mass of the polymer adsorbed to the gold surface. Sulfur-containing polymers were prepared by living anionic polymerization techniques. Radiolabelled polymers were prepared using $\sp3$H-styrene. Polystyrene containing a terminal thiol group (M$\sb{\rm n}$ = 1,000-200,000) adsorbed to gold under conditions that polystyrene did not. At higher molecular weight (M$\sb{\rm n}$ = 500,000) adsorption did not occur. Polystyrene/poly(propylene sulfide) block copolymers adsorbed to gold and the thickness of the adsorbed layer could be controlled by the length of the poly(propylene sulfide) block. This work demonstrates the importance of using organic chemistry to make specifically designed functional polymers that can be used to investigate interfacial phenomena.

Polymers

#### Recommended Citation

Stouffer, Jan M, "Metal-polymer interfaces: Molecular level synthesis and characterization of a platinum-polystyrene interface and polymer monolayers prepared by the spontaneous adsorption of sulfur - functionalized polystyrene on gold surfaces" (1988). Doctoral Dissertations Available from Proquest. AAI8813278.
https://scholarworks.umass.edu/dissertations/AAI8813278

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