Analysis of Poly(Ethylene Terephthalate) (PET) by XPS

Poly(ethylene terephthalate) is used in numerous industrial applications. Successful medical applications are in the area of cardiovascular surgery. Its chemical functionality makes it propitious to grafting biochemical compounds; surface modification by plasma treatment may also be used to improve biocompatibility and modify wetting properties. The analyzed specimen was a commercial film (Mylar A). The main C 1s region was decomposed into three main components which were clearly identified on the recorded spectrum: 284.8, 286.4, and 288.8 eV attributed, respectively, to carbon only bound to carbon and hydrogen [C_—(C,H)], carbon making a single bond with oxygen [C_—O] and carbon of ester [C_OO]. Satellite peaks were found at 291.3, 293.5, and 295.8 eV. The molar ratios C_—(C,H):C_—O:C_OO were 3:0.92:0.91 excluding the satellite peaks, to be compared with the expected values of 3:1:1. The O 1s peak showed two partially resolved components at 531.6 [O_=C—O] and 533.3 eV [O=C—O_] with a satellite at 538.2 eV. The O:C ratio was 27.8:72.2, to be compared with the expected values of 28.6:71.4. The FWHM of the main C 1s components was in the range of 0.90 to 1.23 eV depending on the component and the mode of decomposition; the FWHM of O 1s components was about 1.40 eV.