Molecular structure of polystyrene at Air/Polymer and Solid/Polymer interfaces
IR-visible sum-frequency generation (SFG) spectroscopy has been used in a total internal reflection geometry to study the molecular structure of polystyrene (PS) at PS/sapphire and PS/air interfaces, simultaneously. The symmetric vibrational modes of the phenyl rings dominate the SFG spectra at the PS/air interface as compared to the antisymmetric vibrational modes at the PS/sapphire interface. This indicates approximately parallel orientation of the phenyl rings at the PS/air interface while nearly perpendicular orientation at the PS/sapphire interface, with respect to the surface normal.
Gautam
KS
The University of Akron, Akron, Ohio 44325, USA.
Schwab
AD
Dhinojwala
A
Zhang
D
Dougal
SM
Yeganeh
MS