Poly vinyl pyrrolidone
Polyvinylpyrrolidone (PVP), also commonly called polyvidone or povidone, is a water-soluble polymer made from the monomer N-vinylpyrrolidone:

# Uses

## Medical
PVP was used as a plasma volume expander for trauma victims after the 1950s.
It is used as a binder in many pharmaceutical tablets; it simply passes through the body when taken orally. However, autopsies have found that crospovidone (PVPP) contributes to pulmonary vascular injury in substance abusers who have injected pharmaceutical tablets intended for oral consumption. The long-term effects of crospovidone or povidone within the lung are unknown. PVP added to iodine forms a complex called povidone-iodine that possesses disinfectant properties. This complex is used in various products like solutions, ointment, pessaries, liquid soaps and surgical scrubs. It is known under the trade names Betadine and Pyodine among a plethora of others.
It is used in pleurodesis (fusion of the pleura because of incessant pleural effusions). For this purpose, povidone iodine is equally effective and safe as talc, and may be preferred because of easy availability and low cost.

## Technical
PVP is also used in many technical applications:
- as an adhesive in glue stick and hot-melt adhesives
- as a special additive for batteries, ceramics, fiberglass, inks, and inkjet paper, and in the chemical-mechanical planarization process
- as an emulsifier and disintegrant for solution polymerization
- to increase resolution in photoresists for cathode ray tubes (CRT)
- in aqueous metal quenching
- for production of membranes, such as dialysis and water purification filters
- as a binder and complexation agent in agro applications such as crop protection, seed treatment and coating
- as a thickening agent in tooth whitening gels
- as an aid for increasing the solubility of drugs in liquid and semi-liquid dosage forms (syrups, soft gelatine capsules) and as an inhibitor of recrystallisation
- as an additive to Doro's RNA extraction buffer
- as a liquid-phase dispersion enhancing agent in DOSY NMR 

## Other uses
PVP binds to polar molecules exceptionally well, owing to its polarity. This has led to its application in coatings for photo-quality ink-jet papers and transparencies, as well as in inks for inkjet printers.
PVP is also used in personal care products, such as shampoos and toothpastes, in paints, and adhesives that must be moistened, such as old-style postage stamps and envelopes. It has also been used in contact lens solutions and in steel-quenching solutions. PVP is the basis of the early formulas for hair sprays and hair gels, and still continues to be a component of some.
As a food additive, PVP is a stabilizer and has E number E1201. PVPP (crospovidone) is E1202. It is also used in the wine industry as a fining agent for white wine or some beers. Other references state that polyvinyl pyrrolidone and its derivatives are fully from mineral synthetic origin. Therefore, its use in the production should not be a problem for vegans.
In molecular biology, PVP can be used as a blocking agent during Southern blot analysis as a component of Denhardt's buffer. It is also exceptionally good at absorbing polyphenols during DNA purification. Polyphenols are common in many plant tissues and can deactivate proteins if not removed and therefore inhibit many downstream reactions like PCR.
In microscopy, PVP is useful for making an aqueous mounting medium.

# Safety
The U.S. Food and Drug Administration (FDA) has approved this chemical for many uses, and it is generally considered safe. However, there have been documented cases of allergic reactions to PVP/povidone, particularly regarding subcutaneous (applied under the skin) use and situations where the PVP has come in contact with autologous serum (internal blood fluids) and mucous membranes. For example, a boy having an anaphylactic response after application of PVP-Iodine for treatment of impetigo was found to be allergic to the PVP component of the solution. A woman, who had previously experienced urticaria (hives) from various hair products, later found to contain PVP, had an anaphylactic response after povidone-iodine solution was applied internally. She was found to be allergic to PVP. In another case, a man experiencing anaphylaxis after taking acetaminophen tablets orally was found to be allergic to PVP.
Povidone is commonly used in conjunction with other chemicals. Some of these, such as iodine, are blamed for allergic responses, although testing results in some patients show no signs of allergy to the suspect chemical. Allergies attributed to these other chemicals may possibly be caused by the PVP instead.

# Properties
PVP is soluble in water and other polar solvents. When dry it is a light flaky hygroscopic powder, readily absorbing up to 40% of its weight in atmospheric water. In solution, it has excellent wetting properties and readily forms films. This makes it good as a coating or an additive to coatings.

# History
PVP was first synthesized by Walter Reppe and a patent was filed in 1939 for one of the most interesting derivatives of acetylene chemistry. PVP was initially used as a blood plasma substitute and later in a wide variety of applications in medicine, pharmacy, cosmetics and industrial production.

# Cross-linked derivatives