Quantitative analysis and structure determination of styrene/methyl methacrylate copolymers by pyrolysis gas chromatography.

A pyrolysis gas chromatography (Py-GC) method has been developed to study the composition and microstructure of styrene/methyl methacrylate (STY/MMA) copolymers. The composition was quantified by Py-GC using monomer peak intensity. Because of the poor stability of methyl methacrylate oligomers, neither MMA dimer nor MMA trimers were detected under normal pyrolysis conditions. The number-average sequence length for STY was determined by pure and hybrid trimer peak intensities. The number-average sequence length for MMA was determined by using formulas that incorporate composition and the number-average sequence length of STY. This method is a new approach for the investigation of the microstructure of those copolymers that do not produce dimer and trimer peaks upon pyrolysis.