ToF-SIMS investigation of the thermally induced processes at the surface of polyester based polymer blends

Surface evolution caused by thermal processing at 270 °C of blends of bisphenol-A polycarbonate (PC) with polyethyleneterephthalate (PET) or with polybuthyleneterephthalate (PBT) has been investigated by ToF-SIMS. Such systems are known, upon melt mixing, to undergo transesterification reactions leading to the formation of copolymers. In the case of PET–PC, the transesterification is accompanied by reactions involving the loss of small molecules from the resulting copolymer, whereas the copolymer resulting from the transesterification of PBT–PC is stable at the temperature under consideration. We report on Static SIMS measurements performed on blend samples melt mixed for different times, that show a complex evolution of surface composition, explained also in terms of surface-specific processes, such as segregation of lower surface free energy components. The results from the melt mixed system are compared with those obtained from parallel temperature-programmed ToF-SIMS experiment, performed on spin-cast thin films.