Aqueous solution polymerization vinylpyrrolidone

One half of an aqueous solution of vinylpyrrolidone (VP) is added to the reactor while the other half is added in portions during the polymerization. The polymerization is initiated when hydrogen peroxide and ammonia are added to the reaction mixture. The ammonia serves as a buffer in the solution in order to provide an alkaline condition, thus preventing the splitting off of the acetaldehyde from the monomer during the reaction. The rate of the peroxide-initiated polymerization is expressed as ... 

Early examples of the precipitation approach include the aqueous solution polymerizations reported by Chaimberg et al. [53] for the graft polymerization of polyvinylpyrrolidone onto silica. The nonporous silica particles were modified with vinyltriethoxysilane in xylene, isolated and dispersed in an aqueous solution of vinylpyrrolidone. The reaction was performed at 70°C and initiated by hydrogen peroxide, after which precipitation on the surface occurred, leading to encapsulation. Nagai et al. [54] in 1989 reported on the aqueous polymerization of the quaternary salt of dimethylaminoethyl methacrylate with lauryl bromide, a surface-active monomer, on silica gel. Although the aim was to polymerize only on the surface, separate latex particles were also formed. 

As supplied by the manufacturer, monomeric A/-vinylpyrrolidone is normally inhibited with 0.1% flake sodium hydroxide [24]. This inhibitor may be separated by decantation or filtration. An alternative inhibition system involves the use of gaseous ammonia or organic amines. These inhibitors are said not to interfere with the polymerization process and, in fact, may activate it [25]. This activation by ammonia is not entirely surprising. As will be discussed in Section 3B ( Aqueous Solution Polymerization ), aqueous ammonia has been known as an activator in aqueous systems for many years [1]. Certain impurities which have a distinctly inhibitory effect on the polymerization of A-vinylpyrrolidone are y-butyric acid and y-butyrolactone [26]. 

One of the early patents for the polymerization of AT-vinylpyrrolidone discloses sodium (or potassium) sulfite as polymerization initiators. The aqueous solution polymerization process is carried out in neutral or basic media in order to avoid acetaldehyde formation by decomposition of the monomer. In the more usual oxidative initiation, this may also lead to acetic acid generation. In the more generally used procedures, careful buffering of the reaction medium is usual. 

Aqueous Solution Polymerization of A -Vinylpyrrolidone to High Conversions at 50 C [53]... 

Since N-vinylpyrrolidone is soluble in a great variety of solvents, its polymerization need not be confined to aqueous systems. However, interest in aqueous solution polymerization processes has been so overwhelming that few literature references deal with organic solvent systems as an alternative. 

These results with due regard to the dilution of VP are similar to those for the polymerization in the presence of vinylpyrrolidone homopolymer651. Some differences in the behaviour of the AA-VP/St and AA-VP/AAm systems are connected with the variation in the nature of the hydrophobic styrene and hydrophilic acrylamide. In particular, in this case, the [AA] [VP] ratio is less than unity, because of the capture of a portion of VP units by the hydrophobic styrene nucleus of the micells formed in aqueous solutions of the VP/St copolymer. 

Polymerization and copolymerization of compounds, such as 8-12 with acrylamide, m.aleic anhydride, and 1-vinylpyrrolidone have been performed. The polymeric purine derivatives are generally hygroscopic poly(9-vinyladenine) is soluble in water and gives a hypochromic effect of 13% with ribonucleic acid in aqueous solution. For a review of polycondensation of functionalized purines see ref 234. 

Indeed, photopolymerization of acrylamide in aqueous solution on cell-GEHMP gives cellulose with the surface covered by a poly acrylamide) gel. Similarly, UV initiated polymerization of 2-hydroxyethyl acrylate, 2-(dimethylamino) ethyl methacrylate and A -vinylpyrrolidone carried out with the above functionalized Si(>2 results in the formation of a surfece polymer coating. 

Polymerization Studies. Anionic Polymerization of Caprolactam (the use of (CFs C0)20 (ca. 2 mole %) enabled a lower reaction temperature to be employed and higher yiel and polyamide molecular weights to be obtained]. Soil-retardant Finishing of Cotton Ooth by Vapour-phase Graft Polymerization of Fluoroalkyl Acrylates. Radical Polymerization of a-Fluoroacrylic Acid and -Vinylpyrrolidone in an Aqueous Solution. Perfluoropolyether Esters of Quinones [the preparation of the title compounds by reaction of 1.5-dihydroxyanthraquinone with per-fluoropolyetheracyl fluorides, e.g. CFj-CFi-CF -O-CF(Ci )-CaPj-O-CF(CF,)-C50F, is... 

Poly(vinylpyrrolidone-co-acrylamide) (PVP-Am) forms readily as a high molecular weight polymer in aqueous solutions in the presence of free radical initiators. The preparation and characterization of these copolymers has been reported, jhe copolymers prepared for this study were prepared by homogeneous polymerization as 9.1-20% (w/w) solutions. When the polymerization was complete, usually in 8-24 hours, these high solids solutions were rigid and gel-like in appearance. The linearity of the copolymer was evident on dilution, for they dissolved to form gel free, filtrable viscous aqueous solutions. 

Papisov et a/. have examined the influence of templates consisting of poly-(ethylene glycol)+poly(JV-vinylpyrrolidone) and poly(vinyl alcohol)+polyvinylpyrrolidone) on the polymerization of acrylic and methacrylic acids in aqueous solution at 50 °C. Growing chains of poly(methaciylic acid) apparently complex preferentially with poly(iV-vinylpyrrolidone) the order of complexing strength is given as poly(A/-vinylpyrrolidone) > poly(ethylene glycol) > poly-(vinyl alcohol). 

A more recent development is template polymerization [520 522]. When acrylic acid was polymerized in aqueous solution using potassium persulfate as initiator, the polymerization proceeded very slowly. In the presence of poly(vinylpyrrolidone) but under otherwise identical reaction conditions, the rate of polymerization increased dramatically, depending on the amount of PVP. At nearly equimolar concentrations of PVP and monomer, the rate of polymerization reaches a maximum value, because of the strong interaction between poly(vinylpyrrolidone) and acrylic acid in aqueous solution (Scheme 40) [523]. 

Poly(N-vinylpyrrohdone) (PVP) is a water-soluble and imcharged polymer. The presence of PVP has no influence on the polymorphs of CaCOs precipitation, but has a morphological effect on vaterite and calcite at high PVP concentration [101]. The precipitate obtained in the initial presence of P VA was calcite (run 2 of Table 3). The crystalline products obtained with N-vinylpyrrolidone without addition of the radical initiator were calcite with a trace amount of aragonite (run 1 of Table 3). These results indicate that both the polymer and monomer did not exert any influence on the nucleation and crystal growth of CaCOs. On the contrary, in-situ polymerization of the monomer during the precipitation of CaCOs was carried out by the doublejet method (Keiun et al, 2006, personal communication). After addition of the calcium reactants into the aqueous solution of the monomer was completed, an aqueous solution of KPS as a water-soluble radical initiator was added to the reaction mixture after incubation at 30 °C for several minutes (1, 3, or 20 min). All the products obtained by the in-situ polymerization were pre-... 

A -Vinylpyrrolidone is water-soluble and is usually polymerized in aqueous solution at about 50 C with ammonia and hydrogen peroxide. The polymer is also water-soluble and is isolated by spray-drying. Commercial grades of polyvinylpyrrolidone (PVP) have average molecular weights (Mv) ranging from about 10 000 up to 360 000. 

A patent [60] states that batch polymerizations of 7V-vinylpyrrolidone in aqueous solution with hydrogen peroxide often give rise to gel formation. This difficulty can be overcome by replacing at least part of the water with such substances as isopropyl alcohol, thioglycolic acid, dimethylformamide, ethanolamine, methyl ethyl ketone, trichloroacetic acid or 2-mercaptoethanol. A continuous polymerization procedure is said to be particularly effective. Procedure 3-9 is given here only as an illustration of this patented process. 

A procedure for the continuous polymerization of A-vinylpyrrolidone by chemical initiation has been described in Procedure 2-8. The same authors also claimed the polymerization of a 20 /o aqueous solution of the monomer, containing 0.1 7o of thioglycolic acid passed into a stirred reactor having a hold-up volume of 100 ml at a rate of 52ml/hr, while the reactor was irradiated with a Machlett OE G-50 X-ray tube, 50,000 volts at 50 ma. During a 12-hr period, conversion was 88% of a gel-free polymer having an average Fikentscher K value of 62.5 [60]. 

The complex-formation of PVP with poly(acrylic acid) has been mentioned above. In general, mixing the two polymers in aqueous solution led to products that differed from template-polymerized acrylic acid only in that some, but not all, of the poly(acrylic acid) was grafted onto the poly(vinylpyrrolidone) [48,49]. 

Suspension Copolymerization of Styrene and Acrylonitrile 41-11. Suspension Copolymerization of Acrylamide and Acrylic Acid 41-12. Polymerization of Acrylamide in Aqueous Solution 41-13. Continuous-Solution Polymerization of -Vinylpyrrolidone... 

NVP-HRAM). We examined both synthetic variables and the aqueous (brine) viscometry of the products. The NVP-RAM polymers were synthesized by terpolymerization of acrylamide (AM)f N-octylacrylaxnide (RAM), and N-vinylpyrrolidone (NVP) in water with AIBN initiator and SDS surfactant. Since NVP is a moderately good solvent for N-octyl acrylamide, only low levels of SDS are required. The effects of polymerization variables on product solution properties was studied. 

The spectrophotometric method was used for determining the residual content of vinylpyrrolidone after polymerization in the aqueous phase. It was found that the vinylpyrrolidone content in the solution was reduced to 10%. 

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