QUANTITATIVE ATR FT-IR ANALYSIS OF SURFACE SEGREGATION OF POLYMER BLENDS OF POLYSTYRENE POLY(DIMETHYLSILOXANE)-CO-POLYSTYRENE/

The surface segregation of a series of two-component polymer blends of polystyrene/poly(dimethylsiloxane)-co-polystyrene has been studied by attenuated total reflection Fourier transform infrared (ATR FT-IR) sp ectroscopy. We examined the details of calibration for quantitative AT R FT-IR. The quantitation is based on calibration of Beer's law by tra nsmission FT-IR measurements. The effect of spectral distortion and pe netration depth dependence of radiation wavelength due to ATR sampling is evaluated. ATR spectra are corrected for penetration depth depende nce before being used for quantitation. The corrected ATR spectra were compared with the transmission spectra of the same samples. Peak area ratios using one peak from each component were measured for the deter mination of the concentration of surface poly(dimethylsiloxane). The c orrection and calibration procedure improves the accuracy of quantitat ive surface analysis in the range of micrometer sampling depth. Unlike other approaches for quantification of ATR data on polymers, this met hod can be used for systems with a complex, unknown concentration grad ient near the surface such as the blend system reported here.