Application in polymerization reactions and chemical analysis

Application of PVP in polymerization reactions：

The viscosity and colloid protection function of PVP make it an important application in polymerization reaction, especially when adding a small amount of PVP in lotion polymerization and suspension polymerization, it can play the role of dispersion stability, thickening, and particle size control. For example, in the suspension polymerization of methacrylate and polyamine ester, in the lotion polymerization system of acrylic ester and vinyl acetate, add an appropriate amount of PVP-K60 or PVP and styrene copolymer to make the reaction system disperse evenly and stably. You can also adjust the viscosity, polymer particle size, and particle size distribution by adjusting the molecular weight and amount of PVP added, and improve some properties of the resin. Adding -3% PVPK60 to the suspension polymerization of polyurethane results in a polymer powder with uniform particle size ranging from 800-100 microns and residual monomers less than 0.5%. It can be used for coatings, adhesives, laminated composite materials, and made into thin films with a thickness of up to 100 microns. When used as a coating, the coating degree can be as small as 10 microns.

The addition of PVP-K15 or PVP-K30 with lower molecular weight as emulsifier in some lotion polymerization systems can make the reaction more complete, increase the polymerization rate and improve the mechanical properties of the polymer. When PVP-K15 is added as an emulsifier in the polymerization reaction of methyl methacrylate, it can be completed within half an hour at 50 degrees, and the elastic temperature range of the resulting polymer is 120-280 degrees. However, the elastic temperature range of the polymer obtained without PVP is relatively narrow, at 120-150 degrees. This also indicates that the polymer obtained by using PVP as a dispersing stabilizer has good thermal stability.

Application of PVP in Analytical Chemistry and Catalysts：

The aqueous solution of PVP can be divided into liquid-liquid or liquid-solid phases in the presence of different amounts of (NH4) 2SO4. This system is used for the extraction and separation of metal ions by organic solvents, resulting in a new extraction system. This system has good extraction performance for certain metal ions, such as in the PVP - (NH4) 2SO4-H2O system containing 20% PVP. Arsenazo (III) is used as an extractant to react with a solution containing Zr (IV) and La (III) ions to form a complex. Under certain conditions, the chelation of Zr (IV) and Arsenazo has a high extraction rate in the PVP phase, while the extraction rate of La (III) is very low, thus achieving the separation of Zr (IV) and La (III). In addition, PVP has good complexation with certain metals, such as PVP and trace amounts of Cd, which can be complexed to form PVP Cd. This property can be successfully used to detect trace amounts of cadmium. According to relevant research reports, for the gas-phase carbonylation of methanol, the activity and selectivity of carbon supported colloidal metal catalysts (PVP Rh/C) are much higher than those of pure carbon supported metal rhodium catalysts. This is because the colloidal metal catalyst formed by the combination of rhodium and PVP has a narrow particle size distribution, high dispersion, and increased specific surface area, which not only improves catalytic activity but also enhances reaction selectivity.