SOLVENT EFFECTS ON THE SURFACE-COMPOSITION OF BISPHENOL-A POLYCARBONATE AND POLYDIMELTHYLSILOXANE (BPAC-PDMS) RANDOM BLOCK-COPOLYMERS

The surface compositions of bisphenol A polycarbonate and poly(dimethy lsiloxane) (BPAC-PDMS) random block copolymers were analyzed using ang le-dependent electron spectroscopy for chemical analysis (ESCA) and at tenuated total reflection (ATR) FTIR. The composition tvas measured at sampling depths of 18, 73, and 103 Angstrom with angle-dependent ESCA and at a sampling depth of 4.1 mu m with ATR-FTIR. The present study focuses on examining the quantitative effects of solvent casting and a nnealing on the surface composition of the BPAC-PDMS random block copo lymers of varying bulk compositions. The effects of solvent casting we re evaluated in terms of solvent solubility (or Hildebrand parameter) and solvent volatility (or boiling point). It was found that the casti ng solvents and annealing treatments influenced the surface compositio ns significantly, and each of the solvents gave the polymer film a dif ferent morphology in the near surface region. In addition, a physical picture of the near surface region (103 Angstrom) of siloxane block co polymers cast from selected solvents is compared to the thicker region (similar to 4.1 mu m) probed by ATR-FTIR.