POLYVINYLPYRROLIDONE: STRUCTURE, PROPERTIES, USES, SIDE EFFECTS - CHEMISTRY - 2025

The polyvinylpyrrolidone (PVP) is a polymer of N-vinylpyrrolidone monomer. The polymer goes by many names, including polyvidone and povidone. Polyvinylpyrrolidone was first synthesized by Walter Reppe in 1939.

Reppe reacted acetylene and formaldehyde in the presence of copper acetylide. After several intermediate steps, he obtained butyrolactone, and finally, the monomer vinylpyrrolidone, which polymerizes to form PVP by the action of certain catalysts.

Bottle with polyvinylpyrrolidone powder. Source: LHcheM / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

The upper image shows the solid and amorphous appearance of this polymer. Its molecular structure is of the chain type, the average length of which defines the molar mass, viscosity and other properties of various types of PVP.

The PVP polymer has numerous industrial applications as an adhesive additive. It is used in the coating and in the manufacture of synthetic fibers. It is also used in styling creams and in skin care cosmetics.

Initially PVP was used in medicine to replace or expand plasma. However, it has been shown that PVP generates allergic responses.

Structure

Structural formulas of the monomer vinylpyrrolidone and polyvinylpyrrolidone. Source: Shinobu (talk) (derivative work) / Public domain

The structural formulas of both the vinylpyrrolidone monomer and the polyvinylpyrrolidone polymer are shown above. Note that they are cyclic tertiary amines.

The vinyl group, -CH = CH ₂, is responsible for one vinylpyrrolidone monomer binding to another. Therefore, at this end is where the monomers will join successively until they form a chain with C ₆ H ₉ NO units.

By having an amino ring, PVP is a basic polymer, capable of accepting protons from the environment and of interacting effectively with water molecules. Their interactions are such that the polymer defines a hygroscopic solid.

Properties

Physical appearance

Hygroscopic white or slightly yellow amorphous powder

Names

The IUPAC name for this polymer is 1-ethenylpyrrolidin-2-one.

Chemical formula

(C ₆ H ₉ NO) _n

Molar mass

2,500 - 2,500,000 g / mol

Note the range of molar masses that this polymer can have. This is because there are several types of polyvinylpyrrolidone, each with different properties and specifications. For example, PVP is presented as K-12, with a molar mass between 4,000-6,000; or as K-30, with a molar mass between 40,000-80,000

PVP can also be presented as K-60, K-90, K-120, the latter having a molar mass of between 2,100,000-3,000,000.

Smell and taste

Odorless and tasteless

Density

1.2 g / cm ³

Melting point

150 - 180 ºC

Solubility

It is very soluble in water, with a solubility of 100 mg / mL. In dry state it can absorb up to 40% of its weight in water.

It is soluble in other polar solvents such as ethanol and methanol. But insoluble in ethers, esters and acetone.

pH

3.0 - 5.0

Stability

It is stable but incompatible with strong oxidizing agents, and it is also sensitive to light.

Autoignition temperature

440 ºC

Applications

- Industrial

Glass and ceramics

Polyvinylpyrrolidone is frequently used in the manufacture of glass bottles. Source: Pixnio.

Polyvinylpyrrolidone is used as an additive in adhesives, allowing them to be used in glass, metal and plastic by increasing their strength and hardness. This polymer forms a grease resistant film and raises the softening point of thermoplastics.

It is used as a binder in ceramics, prepared by fire or at high temperatures. The binder ignites during the cooking process, so it has no influence on the final product. In the manufacture of glass, PVP acts as a binder, lubricant and coating agent.

In the glass fibers it helps to fix the dyes. In addition, PVP is part of coatings, ballpoint inks, pigment dispersants in watercolors for commercial art, paper coating, and in the manufacture of waxes and polishes.

Electrical applications

PVP is used in the manufacture of storage batteries, printed circuits, cathode ray tubes. It is used as a binder for metal salts or amalgam in batteries. It is also used in gold, nickel, copper and zinc plating.

Lithography and photography

PVP is used in the production of aluminum emulsions, coating of engravings, storage and adhesion of lithographic plates, thermal recording, etc.

Metallurgy

PVP is used in the processing of ferrous and non-ferrous metals, acting as an ingredient in coatings that help remove materials from their surfaces.

Stabilizer and clarifier

PVP is a clarifier for beer and wine, as it improves their transparency, color and flavor.

- Medicinal

Excipient and dispersant

PVP is used as an excipient and dispersant in tablets, granules and injections. It also stabilizes enzymes and heat sensitive drugs.

Plasma volume expander

PVP began to be used in 1950 as a substitute for plasma in patients with severe trauma. But due to its allergenic action, and its accumulation in the liver, spleen and lungs, it was no longer used for this purpose.

Antibacterial action

PVP couples with iodine, serving as a carrier to take advantage of the disinfecting action. The PVP-iodine or povidone-iodine complex is present in soaps and ointments, fulfilling an important disinfectant action.

Ophthalmological importance

PVP is used in contact lenses, fulfilling a moisturizing and lubricating function. Some preparations for ophthalmic use contain PVP in their formula.

- Others

Personal care

PVP is used as a hair fixing lotion, as well as a hair spray. It is added to sunscreen creams to improve its moisturizing and lubricating condition. In addition, PVP is incorporated in creams and lotions for cleaning and skin care.

Chromatography

PVP is used as a fixing liquid in gas chromatography.

Side effects

Since 1950 PVP began to be used to expand plasma in patients with severe trauma. However, it was found to cause the release of histamine: an amine mediator of allergic processes. And that in addition, the PVP ended up sequestered in the liver and spleen.

PVP can cause pulmonary interstitial fibrosis that can be reversed if exposure to the polymer is not prolonged. Several episodes of allergic processes have been reported, which could be related to PVP; especially when it comes into contact with subcutaneous body fluids.

A case of urticaria has been reported related to the use of hair products in which PVP was present. Likewise, there was a case of allergy in a patient treated with PVP-iodine, also pointing out the allergenic role of PVP in some cases of dermatitis.

References

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2. Wikipedia. (2020). Polyvinylpyrrolidone. Recovered from: en.wikipedia.org
3. Chemical Book. (2017). Polyvinylpyrrolidone. Recovered from: chemicalbook.com
4. Elsevier BV (2020). Polyvinylpyrrolidone. ScienceDirect. Recovered from: sciencedirect.com
5. Food Safety. (2014). Polyvinylpyrrolidone.. Recovered from: jstage.jst.go.jp
6. QuimiNet. (May 21, 2008). What is polyvinyl pyrrolidone? Recovered from: quiminet.com