Pyrolysis-gas chromatography-mass spectrometry for studying N-vinyl-2-pyrrolidone-co-vinyl acetate copolymers and their dissolution behaviourAU: Chojnacka, Aleksandra

• Published in: Analytica chimica acta Vol. 706; no. 2; pp. 305 - 311
• Main Authors: Ghaffar, Abdul, Feilden, Andrew, Treacher, Kevin, Janssen, Hans-Gerd, Schoenmakers, Peter
• Format: Journal Article
• Language: English
• Published: 14.11.2011
• Subjects: Acetates; Chromatography; Copolymers; Dissolution; Molecular weight; Monomers; Spectrometry; Spectroscopy
• ISSN: 0003-2670
• DOI: 10.1016/j.aca.2011.05.052

Knowledge on the solubility behaviour and dissolution rate of speciality and commodity polymers is very important for the use of such materials in high-tech applications. We have developed methods for the quantification and characterization of dissolved copolymers of N-vinyl-2-pyrrolidone (VP) and vinyl acetate (VA) during dissolution in water. The methods are based on pyrolysis (Py) performed in a programmed-temperature vaporization injector with subsequent identification and quantification of the components in the pyrolysate using capillary gas chromatography-mass spectrometry (GC-MS). By injecting large volumes and applying cryo-focussing at the top of the column, low detection limits could be achieved. The monomer ratio was found to have the greatest effect on the dissolution rate of the PVP-co-VA copolymers. The material with the highest amount of VA (50%) dissolves significantly slower than the other grades. Size-exclusion chromatography (SEC) and Py-GC-MS were used to measure molecular weights and average chemical compositions, respectively. Combined off-line SEC//Py-GC-MS was used to determine the copolymer composition (VP/VA ratio), as a function of the molecular weight for the pure polymers. In the dissolution experiments, a constant VP/VA ratio across the dissolution curve was observed for all copolymers analysed. This suggests a random distribution of the two monomers over the molecules.