A fully calibrated and validated TGA-GC–MS is proposed for the quantitative analysis of diethylphosphate- end capped polymers. It allows the determination of the amount of phosphorous in polymeric samples and also thedetermination of the number of repeating units per chain end. Since no sample pretreatments are required polymeric films supported on inert substrates can be directly analyzed even in ultrathinfilms with thickness of few tens of nanometers. Finally, the chromatographic profile of the species evolving during the thermal degradation depend on the polymeric film thickness allowing that information concerning the polymer stability anddegradation mechanism at different size scale can be obtained. Considering the widespread interest for thin and ultrathin films of polymers containing phosphorous groupsfor brush-based technologies, the proposed method can be helpful in various areas, including …