Solubility PVP

One practical result of this strong interaction is the employment of PVP to remove unwanted phenoHcs such as bitter tanins from beer and wine. This process is more easily carried out with insoluble crospovidone, which can be regenerated for reuse with dilute base (104). Soluble PVP has been employed to prevent photoyeUowing of paper by complexing free phenoHc hydroxyl groups in lignin (105). 

Solubility. One of PVP s more outstanding attributes is its solubility in both water and a variety of oiganic solvents. PVP is soluble in alcohols, acids, ethyl lactate, chlorinated hydrocarbons, amines, glycols, lactams, and nitroparaffins. Solubility means a minimum of 10 wt % PVP dissolves at room temperature (moisture content of PVP can influence solubility). PVP is insoluble in hydrocarbons, ethers, ethyl acetate, JW-butyl-4-acetate, 2-butanone, acetone, cyclohexanone, and chlorobenzene. Both solvent polarity and H-bonding strongly influence solubility (77). 

The most surprising feature of the behavior of PS-PVP-PEO micelles with water-soluble PVP (protonized) and PEO blocks in acidic media is their aggregation in the region of low pH. Because it is a rather unexpected phenomenon, we studied it in more detail. The distributions of relaxation times obtained by DLS are bimodal (Eig. 8). Angular dependences (not shown) prove that both fast and slow relaxation modes correspond to diffusive processes. The intensity of the slow mode decreases with increasing pH and decreasing copolymer concentration. At very low copolymer and HCl concentrations, the slow mode disappears completely. The DLS measurements thus show that PS-PVP-PEO solutions contain two types... 

Also interesting would be a study of this reduction with ordinary, water-soluble PVP, prepared with a nonoxidizing initator. If the reduction were successful, the final polymer would have an unusual structure with a tertiary amine and a secondary hydroxl group on adjacent carbon atoms. 

In May-June, the growing parts of youg pine needles (10g) are ground in 180 ml of Tris-HCI 100 mM, pH 8.3, 0.15 M saccharose, 2 mM p-mercaptoethanol, soluble PVP 1%. After centrifugation, lOO.OOOg supernatants are frozen at -50°C for subsequent cell-free assays and purification procedure. All the above steps and all subsequent operations were carried out at 4°C. 

A large volume of literature exists for PO blends with easily crosslinkable elastomers, but the information on radiation processing and degradation of HTPB is scarce. For dimensionally recoverable applications a blend of LCP with PVDF or PE was radiation crosslinked. Similarly, PSF or PES was blended with water-soluble PVP and crosslinked to make it water insoluble for medical or food applications. For the use in cable jackets and heat-shrinkable applications PVDF or a copolymer of tetrafluoroethylene and ethylene (ETFE) could be compounded with a thermoplastic elastomer, formed and radiation crosslinked. Adjusting composition and irradiation dose produced a series of materials with good balance of tensile strength and elongation. ... 

It has also been found that polymers possessing functional groups such as amines and pyridines are soluble in pregeUed sol solutions, especially, poly(2-vin5ipyridine) and poly(N-vinylpyrroHdinone) (PVP) (49). There, materials were made as part of a study of the synthesis of nonshrinking sol—gel-derived networks (49). 

Cross-linked versions of water-soluble polymers swollen in aqueous media are broadly referred to as hydrogels (52) and have a growing commercial utility in such apphcations as oxygen-permeable soft contact lenses (qv) (53) (Table 4) and controUed-release pharmaceutical dmg deflvery devices (54). Cross-linked PVP and selected copolymers fit this definition and are of interest because of the following stmcture/performance characteristics ... 

Practical appHcations have been reported for PVP/ceUulosics (108,119,120) and PVP/polysulfones (121,122) in membrane separation technology, eg, in the manufacture of dialysis membranes. Electrically conductive polymers of polyaruline are rendered more soluble and hence easier to process by complexation with PVP (123). Addition of small amounts of PVP to nylon 66 and 610 causes significant morphological changes, resulting in fewer but more regular spherulites (124). 

Polyvinylpyrrolidone (PVP) is water-soluble polymer, whieh is widely used in various industries and agrieulture beeause of high inelination to the eomplex formation and eapaeity to stabilization of different systems. 

Poly(vinyl pyrrolidone) (PVP) was introduced by the Germans in World War II as a blood plasma substitute.A water-soluble polymer, its main value is due to its ability to form loose addition compounds with many substances. 

The synthetic approach is very simple and does not require any special set up. In a typical room temperature reaction, 1.0 mL aqueous solution of cadmium chloride was added to 20 mL aqueous solution of soluble starch in a 50 mL one-necked round-bottom flask with constant stirring at room temperature. The pH of the solution was adjusted from 6 to 11 using 0.1 M ammonia solution. This was followed by a slow addition of 1.0 mL colourless selenide ion stock solution. The mixture was further stirred for 2 h and aged for 18 h. The resultant solution was filtered and extracted with acetone to obtain a red precipitate of CdSe nanoaprticles. The precipitate was washed several times and dried at room temperature to give a material which readily dispersed in water. The same procedure was repeated for the synthesis of PVA and PVP - capped CdSe nanoparticles by replacing the starch solution with the PVA and PVP polymers while the synthesis of elongated nanoparticles was achieved by changing the Cd Se precursor ratio from 1 1 to 1 2. The synthesis of polymer capped ZnSe nanoparticles also follows the same procedure except that ZnCb solution was used instead of CdCb solution. 

The solid is used as a heterogeneous catalyst or as a water-soluble system in biphasic conditions in the hydrogenation of benzene and pheny-lacetylene [65]. The heterogeneous system Rh-PVP is investigated in the solid/liquid catalytic hydrogenation of benzene with a ratio of 1/34000 at 80 °C and 20 bar H2. The conversion into cyclohexane is about 60% after 200 h of reaction time. In a water/benzene biphasic condition at 30 °C and under 7 bar H2, complete hydrogenation (Scheme 2) for a molar ratio of 2000 is observed after 8 h giving a TOF = 675 h (related to H2 consumed), never-... 

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