Deposition and Characterization of Roughened Surfaces.

Area of Science:

• Materials Science
• Polymer Science
• Surface Chemistry

Background:

• Phase separation in polymer solutions is triggered by solvent evaporation.
• Polymer films are crucial for applications like solar cells and catalysis.
• Tailoring film morphology is key to optimizing substrate performance.

Purpose of the Study:

• To investigate phase separation in polystyrene (PS) and polyvinyl acetate (PVAc) blends.
• To characterize the morphology, strain, and surface properties of deposited films.
• To explore the application of these films as substrates for surface-enhanced Raman scattering (SERS).

Main Methods:

• Dissolving PS and PVAc in chlorobenzene at various ratios.
• Depositing thin films on glass substrates using spin coating.
• Analyzing film properties via Raman scattering, morphology, strain, and surface area measurements.

Main Results:

• Incompatible polymers formed roughened PVAc islands on a PS matrix.
• Increased PVAc concentration led to expanded porous regions and taller PVAc tips.
• An optimal ratio of 75% PVAc and 25% PS yielded a uniformly roughened surface.
• The roughened surface demonstrated a >500% increase in SERS signal intensity.

Conclusions:

• Phase separation in PS/PVAc blends can create highly roughened surfaces with tunable porosity.
• The optimized roughened surface significantly enhances Raman signal through the 'rod effect'.
• These tailored polymer films show promise as effective substrates for SERS applications.