A time-of-flight secondary ion mass spectrometry study of sequential polymers with a well-defined segmental length

Two series of sequential polymers (6FBA–Cn and BA–Cn) have been synthesized by phase-transfer catalyzed polyetherification of 1,n-dibromoalkane (n=4,6,8,10,12,14 and 18) with 4,4′-(hexafluoroisopropylidene)diphenol (6FBA) and bisphenol A (BA). The effects of the flexible aliphatic segment length on the structure of secondary ions were investigated. The characteristic secondary positive and negative ions in the time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra are related to the chemical structures of the sequential BA–Cn and 6FBA–Cn polymers. The emission of the characteristic secondary positive and negative ions occurs after cleavage of the C–O bonds of the polymer repeat units. In the ToF-SIMS negative spectra, a series of small peaks separated by 14 amu provides the information about the flexible segment lengths of the repeat units of the BA–Cn and 6FBA–Cn polymers and can be used to directly determine the number of the –CH2– groups, n, of the flexible segment.