FOURIER-TRANSFORM INFRARED AND ELECTRON-SPECTROSCOPY FOR CHEMICAL-ANALYSIS STUDIES OF BLOCK COPOLYMERS OF STYRENE AND DIMETHYLSILOXANE

The surface segregation of poly(dimethylsiloxane) (PDMS) in chloroform solution cast films of styrene and dimethylsiloxane block copolymers in AB diblock and ABA and BAB triblock types was investigated by electron spectroscopy for chemical analysis and attenuated total reflectance (ATR) FTIR. The results show that the PDMS surface segregation is mainly dependent on the architectures of the block copolymers and the PDMS block length. AB-type diblock copolymers exhibit a relatively thicker pure PDMS surface layer, and the PDMS surface segregation effects were detected up to the ATR-FTIR sampling depth. All three types of block copolymers present much higher PDMS concentrations in the outermost surface region (about 0-27 angstrom from the air interface) than in the bulk materials. PDMS surface segregation changes were observed for some of the block copolymers after annealing the as-cast films.