Chemisorption and thermal decomposition of polyvinylpyrrolidone adsorbed by pyrogenic silica as model of surface reactions on atmospheric microparticles

• Date: 2001
• Main Authors: Pokrovskiy, V. A., Bogatyrov, V. M.
• Format: Article
• Language: English
• Published: Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine 2001
• Online Access: https://surfacezbir.com.ua/index.php/surface/article/view/72
• Journal Title: Surface

Thermal decomposition of polyvinylpyrrolidone (PVP) in bulk and adsorbed on ultra-fine silica surface was studied as a model of thermal transformation of anthropogenic environmental pollutants on the surface of atmospheric micro-particles, Three stages of polymer decomposition with maxima at 150, 280 and 360°C were observed for bulk samples of PVP of average molecular mass about 10 000. Pyrrolidone (m/z 85) was the main product resulting from elimination of side groups in main polymer chain. Rupture of main chain itself resulting in elimination of vinylpyrrolidone (m/z 111) was the main process at high temperature and occurred in single stage with maximum at 360°C. Thermal decomposition of PVP thin layers on the surface of ultra-fine pyrogenic silica was also studied. Samples were obtained by adsorption of PVP on Aerosil A-300 surface and contained 5.8, 16.9 and 29.3 mass % of polymer. Unlike to silica-free samples, only two maxima of 85 m/z elimination (at 120 and 360 °C) were observed, majority of pyrrolidone being produced during the high-temperature stage. Details of polymer decomposition depended essentially upon portion of adsorbed PVP. The conclusion was done that adsorption slows down the conformation exchange and effects the process of polymer decomposition.