ABSTRACT
Polyvinylpyrrolidone (PVP) is readily prepared by the polymerization of N-vinyl-2-pyrrolidone (NVP). The cross-linked homopolymer, PVPP, is produced using a caustic catalyst or by using a cross-linking agent to form an insoluble hydrophilic polymer. The polymer is insoluble in water and virtually all organic solvents. The molecular weight distribution curve of PVP is generally broad due to transfer reactions during the polymerization. These transfer reactions occur more frequently in the preparation of the relatively high molecular weight polymers because the degree of branching is greater than in the lower molecular weight polymers. Polyvinylpyrrolidone is relatively inert to chemical modification. In powder form the various grades of PVP are quite stable at room temperature. When protected from mould, aqueous solutions are also stable. PVP also contains small amounts of 2-pyrrolidone, which is due to the hydrolysis of NVP during the polymerization process.
