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]. 

Both bulk and solution polymerizations of A -vinylpyrrolidone have been initiated at 0°-100°C by metal salts such as the chloride, bromide, iodide, sulfate, and nitrate of mercury(II) the chloride, bromide, and iodide of bismuth and the chloride of antimony [30]. The polymerization may be sufficiently exothermic to require external cooling. Procedure 3-3 is given here as an illustration of this patented process. 

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. 

A review article by Fikentscher and Herrle [1] discusses the solution polymerization of this monomer in considerable detail. This material is summarized here so that readers may develop their own reaction procedures on the basis of the information. The reaction conditions based on this work are reliable for the preparation of copolymers of N-vinylpyrrolidone and vinyl acetate [47]. 

TABLE XII Effect of Increasing A -Vinylpyrrolidone Concentrations in Solution Polymerization [53]"... 

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. 

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... 

When the ratio of template to acid is close to 0.5, the viscosity of the product is more than 3 times higher than the viscosity of the polymer obtained without the template. PEO participates in the change of local concentration by interaction with carbonyl groups, but not in the activation. Solution of LiCl in N-methylpyrrolidone with PlOCeHsls was found very effective system for synthesis of amides by the direct reaction of acids with amines in the presence of polymeric matrix. High molecular weight poly(aminoacids) obtained by direct polycondensation reaction, promoted by triphenyl phosphite and LiCl in the presence of poly(vinylpyrrolidone), were synthesized by Higashi et al The results for polymerization of L-leucine in the presence of poly(vinyl pyrrolidone) are presented in the Table 6.3. 

N-Carboxyanhydride of a-amino add is polymerized by the nucleophile-containing polymers such as poly(N-vinyl-2-ethylimidazole), poly(N-vinyl-2-ethylimidazole-co-acrylamide) and poly(N-vinyl-2-ethylimidazole-co-N-vinylpyrrolidone) (102, 103). The rate of polymerization increases with the order of pyrrolidone, amide and imidazole moieties. The order corresponds to the magnitude of the bond formation which is observed in 1R measurement. The rate also increases with the content of pyrrolidone moiety. The rate in N, N -dimethylformamide solution which is unfavorable to the hydrogen bond formation is lower than that in acetophenone. These results show that the hydrogen bond formation is notable as the binding. 

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. 

Acetylene and formaldehyde are reacted in the presence of a highly active catalyst to form butynediol, which is hydrogenated to butanediol and then cyclodehydrogenated to form butyrolactone. Pyrrolidone is produced by reacting butyrolac-tone with ammonia. This is followed by a vinylation reaction in which pyrrolidone and acetylene are reacted under pressure. The monomer vinylpyrrolidone is then polymerized in solution, using a catalyst. Crospovidone is prepared by a popcorn polymerization process. 

The same standards can be separated with poly(ethylene glycol) (PEG 200 molecular mass 200,000 g mol-1) in a 5% wlw) solution or with poly(vinylpyrrolidone) K90 (1% wlw). As can be seen in Fig. 6, the separation ranges and the broadness of the peaks are quite different, because of differences in the sieving ranges of the polymeric additives. 

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... 

PVP is a completely synthetic macromolecule, produced by polymerization of vinylpyrrolidone (Fig. 6). It was introduced by Hecht and Weese (1943) as a plasma substitute. Its thread-like molecules are highly water soluble and form viscous solutions, which can be sterilized and are stable for many years. Preparations for-... 

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. 

Polyfl -vinylpyrrolidone) [PVP, poly(A/-vinyl-2-pyrrolidone)] n, A highly water-soluble polymer prepared by the addition polymerization of 1 -vinyl-2-pyrrolidone (for structure). Molecular weights range from 10,000 to 360,000. Solutions of the polymer are used as protective colloids and emulsion stabilizers, and it has been used as a substitute for human blood plasma. PVP films are clear and hard, but can be plasticized. 

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. 

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