Effect of Phosphate Salt Concentration and Solution pH on the Aqueous‐Phase Homo and Copolymerization of N‐Vinyl Pyrrolidone. Issue 4 (17th May 2018)

• Record Type: Journal Article
• Authors: Borges, Fernando T. P.; Papavasiliou, Georgia; Murad, Sohail; Teymour, Fouad
• Other Names: Hutchinson Robin guestEditor.; Soares João guestEditor.
• Is Part Of: Macromolecular reaction engineering. Volume 12:Issue 4(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-05-17
• Subjects: NVP -- phosphate salts -- polymeric materials -- polymerization reaction engineering -- polymerization reaction modeling; Polymers -- Periodicals; Polymerization -- Periodicals; Reaction mechanisms (Chemistry) -- Periodicals; Electronic journals; 547.705
• DOI: 10.1002/mren.201800012
• Languages: English
• ISSNs: 1862-832X

Abstract

Abstract: N ‐vinyl pyrrolidone (NVP) aqueous‐phase polymerization is known to depend on the degree of hydration of the NVP molecules, resulting in an increase in the rate of propagation with decreasing monomer concentration. When potassium monophosphate and sodium hexametaphosphate are added to the monomer solution the reaction kinetics slow down, with the degree of retardation being dependent on salt‐to‐monomer concentration ratio. Using polymerization reaction models in combination with ion coordination theory, this effect can be associated with an active interaction of the ions in solution with the NVP molecules. When varying the solution pH, an optimum operating zone ranging approximately from pH 4 to pH 7 for the NVP–V‐50 2, 2′‐Azobis(2‐methylpropionamidine) dihydrochloride (AAPH) system is found. Potassium persulfate is unable to initiate NVP homopolymerization. The addition of poly(ethylene glycol) diacrylate as a comonomer reduces the kinetic slow‐down caused by the addition of salts or by extreme pH and significantly increases the overall conversion rate. Abstract : The effects of pH and phosphate salt concentration on the kinetics of aqueous‐phase N ‐vinyl pyrrolidone (NVP) polymerization are studied. Results show significant impact of both factors. Thermodynamics theory partially explains the salt effect. Both effects are attenuated in copolymerization systems.