Thermogravimetric analysis of poly(ε-caprolactam) and poly[(ε-caprolactam)-co-(ε-caprolactone)] polymers

The thermal degradation of poly(ε-caprolactam) and its copolymers with ε-caprolactone has been studied by high-resolution thermogravimetric analysis (TGA), followed by the analysis of evolved gas via a simultaneous coupling to Fourier transform infrared spectrometry (FTIR) and mass spectrometry (MS). Poly(ε-caprolactam) and poly(ε-caprolactone) polymers are, respectively, degraded at different temperatures, rendering this study to be particularly useful in determining the structure of their copolymers, i.e. random or blocky-like copolymers. The poly[(ε-caprolactam)-co-(ε-caprolactone)] polymers have been synthesized in bulk by anionic ring-opening copolymerization promoted by ε-caprolactammagnesium bromide in a temperature range from 120 to 180°C. A multi-step degradation was observed by TGA, and characterization of the evolved gas by FTIR and MS gives credit to some blocky-like enchainment of the comonomers. This assignation has been further confirmed by TGA directly performed on blends of poly(ε-caprolactam) and poly(ε-caprolactone) as obtained by solvent casting.