Characterization of ultra-thin polymeric films by Gas chromatography-Mass spectrometry hyphenated to thermogravimetry

• A TGA-GC-MS method was optimised, validated and successfully applied.
• The method allows investigating the thermal behavior of ultrathin copolymer layers.
• The optimized TGA-GC-MS method is highly versatile.
• Bulk materials, thick films, thin and ultrathin films can be analyzed.
• The method is able to highlight differences in samples with small differences in thickness.

Polymeric materials are widely employed to build up tunable nanomasks for nano-patterning technologies. Ultrathin polymer layers are involved in this process. A Thermo Gravimetric Analysis–Mass Spectrometry (TGA-GC-MS) method was optimised, validated and successfully applied to investigate the thermal behavior of ultrathin poly(styrene-r-methylmethacrylate) random copolymer layers P(S-r-MMA) grafted to a silicon wafer surface. The interface between TGA and MS is highly versatile since many instrumental parameters (i.e. loop volumes, pulsed sampling frequencies, acquisition modalities, carrier gases, flow rates) can be easily tuned. Samples featuring substantial scale difference, i.e. bulk materials, thick films (few μm thickness), thin and ultrathin films (few nm thickness) can be analyzed without any instrumental modification or sample pretreatments. The TGA-GC-MS analysis was used to highlight subtle differences in samples featuring different thicknesses, in the 2–6 nm range, and subjected to various thermal treatments, thus indicating that this hyphenated technique could be successfully applied to the investigation of ultrathin polymer films.