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.