Influence of tacticity on polymer surfaces studied by ToF-SIMS

Poly(methylmethacrylate) (PMMA) and polystyrene (PS) thin films of different tacticities have been analysed by time-of-flight (ToF) SIMS in order to look for a possible influence of the stereoregularity on their fingerprint spectra (m/z less than or equal to 200). Because, at first glance, the spectra of samples with different tacticities seemed rather similar, the intensity ratios between secondary ions from main polymer chain and those from pendant group were evaluated. By this procedure, it was found that isotactic PMMA can be clearly distinguished from syndiotactic and atactic PMMA, A lower concentration of the methyl-methacrylate pendant group was detected at the surface of the isotactic sample. In the case of PS, more phenyl groups were found to be present at the surface of isotactic PS and an empirical criterion is proposed to differentiate between atactic and isotactic PS.