Polyvinyl alcohol

Last updated
Polyvinyl alcohol
Polyvinyl Alcohol Structural Formula V1.svg
Sample of Polyvinyl alcohol.jpg
Names
Other names
PVOH; Poly(Ethenol), Ethenol, homopolymer; PVA; Polyviol; Vinol; Alvyl; Alcotex; Covol; Gelvatol; Lemol; Mowiol; Mowiflex, Alcotex, Elvanol, Gelvatol, Lemol, Nelfilcon A, Polyviol und Rhodoviol
Identifiers
ChEMBL
ChemSpider
  • none
ECHA InfoCard 100.121.648 OOjs UI icon edit-ltr-progressive.svg
E number E1203 (additional chemicals)
KEGG
RTECS number
  • TR8100000
UNII
Properties
(C 2 H 4 O)x
Density 1.19–1.31 g/cm3
Melting point 200 °C (392 °F; 473 K)
log P 0.26 [1]
1.477 @ 632 nm [2]
Hazards
NFPA 704 (fire diamond)
NFPA 704.svgHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
1
0
Flash point 79.44 °C (174.99 °F; 352.59 K)
Lethal dose or concentration (LD, LC):
14,700 mg/kg (mouse)
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Polyvinyl alcohol (PVOH, PVA, or PVAl) is a water-soluble synthetic polymer. It has the idealized formula [CH2CH(OH)]n. It is used in papermaking, textile warp sizing, as a thickener and emulsion stabilizer in polyvinyl acetate (PVAc) adhesive formulations, in a variety of coatings, and 3D printing. It is colourless (white) and odorless. It is commonly supplied as beads or as solutions in water. [3] [4] Without an externally added crosslinking agent, PVA solution can be gelled through repeated freezing-thawing, yielding highly strong, ultrapure, biocompatible hydrogels which have been used for a variety of applications such as vascular stents, cartilages, contact lenses, etc. [5]

Contents

Although polyvinyl alcohol is often referred to by the acronym PVA, more generally PVA refers to polyvinyl acetate, which is commonly used as a wood adhesive, sealer and water soluble plastic.

Uses

PVA is used in a variety of medical applications because of its biocompatibility, low tendency for protein adhesion, and low toxicity. Specific uses include cartilage replacements, contact lenses, and eye drops. [6] Polyvinyl alcohol is used as an aid in suspension polymerizations. Its largest application in China is its use as a protective colloid to make PVAc dispersions. In Japan its major use is the production of Vinylon fiber. [7] This fiber is also manufactured in North Korea for self-sufficiency reasons, because no oil is required to produce it. Another application is photographic film. [8]

PVA-based polymers are used widely in additive manufacturing. For example, 3D printed oral dosage forms demonstrate great potential in the pharmaceutical industry. It is possible to create drug-loaded tablets with modified drug-release characteristics where PVA is used as a binder substance. [9]

Medically, PVA-based microparticles have received FDA 510(k) approval to be used as embolisation particles to be used for peripheral hypervascular tumors. [10] It may also used as the embolic agent in a Uterine Fibroid Embolectomy (UFE). [11] In biomedical engineering research, PVA has also been studied for cartilage, orthopaedic applications, [12] and potential materials for vascular graft. [13]

PVA is commonly used in household sponges that absorb more water than polyurethane sponges.

Polyvinyl acetals

Polyvinyl acetals are prepared by treating PVA with aldehydes. Butyraldehyde and formaldehyde afford polyvinyl butyral (PVB) and polyvinyl formal (PVF), respectively. Preparation of polyvinyl butyral is the largest use for polyvinyl alcohol in the US and Western Europe.

Preparation

Unlike most vinyl polymers, PVA is not prepared by polymerization of the corresponding monomer, since the monomer, vinyl alcohol, is thermodynamically unstable with respect to its tautomerization to acetaldehyde. Instead, PVA is prepared by hydrolysis of polyvinyl acetate, [3] or sometimes other vinyl ester-derived polymers with formate or chloroacetate groups instead of acetate. The conversion of the polyvinyl esters is usually conducted by base-catalysed transesterification with ethanol:

[CH2CH(OAc)]n + C2H5OH → [CH2CH(OH)]n + C2H5OAc

The properties of the polymer are affected by the degree of transesterification.

Worldwide consumption of polyvinyl alcohol was over one million metric tons in 2006. [7] Large producers include Kuraray and Sekisui Specialty Chemicals, while mainland China has installed a number of very large production facilities in the past decade[ clarification needed ] and currently accounts for 45% of world capacity.

Structure and properties

PVA is an atactic material that exhibits crystallinity. In terms of microstructure, it is composed mainly of 1,3-diol linkages [−CH2−CH(OH)−CH2−CH(OH)−], but a few percent of 1,2-diols [−CH2−CH(OH)−CH(OH)−CH2−] occur, depending on the conditions for the polymerization of the vinyl ester precursor. [3]

Polyvinyl alcohol has excellent film-forming, emulsifying and adhesive properties. It is also resistant to oil, grease and solvents. It has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties. However, these properties are dependent on humidity: water absorbed at higher humidity levels acts as a plasticiser, which reduces the polymer's tensile strength, but increases its elongation and tear strength.

Safety and environmental considerations

Polyvinyl alcohol is widely used, thus its toxicity and biodegradation are of interest. Tests showed that fish (guppies) are not harmed, even at a poly(vinyl alcohol) concentration of 500 mg/L of water. [3]

There are several different grades of PVA depending on the degrees of polymerization and hydrolysis, which will affect their physical and chemical properties as well as their biodegradability. [3] Aqueous solutions of PVA degrade faster, which is why PVA grades that are highly water-soluble tend to have a faster biodegradation [14] . Not all PVA grades are readily biodegradable, but studies show that high water-soluble PVA grades such as the ones used in detergents can be readily biodegradable according to OECD screening test conditions. [15]

Orally administered PVA is relatively harmless. [16] The safety of polyvinyl alcohol is based on some of the following observations: [16]

See also

Related Research Articles

<span class="mw-page-title-main">Polyethylene</span> Most common thermoplastic polymer

Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, etc.). As of 2017, over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market.

PVA may refer to:

<span class="mw-page-title-main">Polyvinyl acetate</span> PVA, adhesive used for porous materials

Polyvinyl acetate (PVA, PVAc, poly(ethenyl ethanoate)), commonly known as wood glue, PVA glue, white glue, carpenter's glue, school glue, or Elmer's Glue in the US, is a widely available adhesive used for porous materials like wood, paper, and cloth. An aliphatic rubbery synthetic polymer with the formula (C4H6O2)n, it belongs to the polyvinyl ester family, with the general formula −[RCOOCHCH2]−. It is a type of thermoplastic.

In polymer chemistry, emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomers, and surfactants. The most common type of emulsion polymerization is an oil-in-water emulsion, in which droplets of monomer are emulsified in a continuous phase of water. Water-soluble polymers, such as certain polyvinyl alcohols or hydroxyethyl celluloses, can also be used to act as emulsifiers/stabilizers. The name "emulsion polymerization" is a misnomer that arises from a historical misconception. Rather than occurring in emulsion droplets, polymerization takes place in the latex/colloid particles that form spontaneously in the first few minutes of the process. These latex particles are typically 100 nm in size, and are made of many individual polymer chains. The particles are prevented from coagulating with each other because each particle is surrounded by the surfactant ('soap'); the charge on the surfactant repels other particles electrostatically. When water-soluble polymers are used as stabilizers instead of soap, the repulsion between particles arises because these water-soluble polymers form a 'hairy layer' around a particle that repels other particles, because pushing particles together would involve compressing these chains.

<span class="mw-page-title-main">Hydrogel</span> Soft water-rich polymer gel

A hydrogel is a biphasic material, a mixture of porous, permeable solids and at least 10% by weight or volume of interstitial fluid composed completely or mainly by water. In hydrogels the porous permeable solid is a water insoluble three dimensional network of natural or synthetic polymers and a fluid, having absorbed a large amount of water or biological fluids. These properties underpin several applications, especially in the biomedical area. Many hydrogels are synthetic, but some are derived from nature. The term 'hydrogel' was coined in 1894.

<span class="mw-page-title-main">Acrylic acid</span> Chemical compound

Acrylic acid (IUPAC: propenoic acid) is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a characteristic acrid or tart smell. It is miscible with water, alcohols, ethers, and chloroform. More than a million tons are produced annually.

<span class="mw-page-title-main">Vinyl alcohol</span> Chemical compound

Vinyl alcohol, also called ethenol or ethylenol, is the simplest enol. With the formula CH2CHOH, it is a labile compound that converts to acetaldehyde immediately upon isolation near room temperature. It is not a practical precursor to any compound.

<span class="mw-page-title-main">Ethylene-vinyl acetate</span> Chemical compound

Ethylene-vinyl acetate (EVA), also known as poly(ethylene-vinyl acetate) (PEVA), is a copolymer of ethylene and vinyl acetate. The weight percent of vinyl acetate usually varies from 10 to 50%, with the remainder being ethylene. There are three different types of EVA copolymer, which differ in the vinyl acetate (VA) content and the way the materials are used.

<span class="mw-page-title-main">Vinyl acetate</span> Chemical compound

Vinyl acetate is an organic compound with the formula CH3CO2CH=CH2. This colorless liquid is the precursor to polyvinyl acetate, ethene-vinyl acetate copolymers, polyvinyl alcohol, and other important industrial polymers.

In polymer chemistry, vinyl polymers are a group of polymers derived from substituted vinyl monomers. Their backbone is an extended alkane chain [−CH2−CHR−]. In popular usage, "vinyl" refers only to polyvinyl chloride (PVC).

<span class="mw-page-title-main">Sodium polyacrylate</span> Anionic polyelectrolyte polymer

Sodium polyacrylate (ACR, ASAP, or PAAS), also known as waterlock, is a sodium salt of polyacrylic acid with the chemical formula [−CH2−CH(CO2Na)−]n and has broad applications in consumer products. This super-absorbent polymer (SAP) has the ability to absorb 100 to 1000 times its mass in water. Sodium polyacrylate is an anionic polyelectrolyte with negatively charged carboxylic groups in the main chain. It is a polymer made up of chains of acrylate compounds. It contains sodium, which gives it the ability to absorb large amounts of water. When dissolved in water, it forms a thick and transparent solution due to the ionic interactions of the molecules. Sodium polyacrylate has many favorable mechanical properties. Some of these advantages include good mechanical stability, high heat resistance, and strong hydration. It has been used as an additive for food products including bread, juice, and ice cream.

<span class="mw-page-title-main">Enol ether</span> Class of chemical compounds

In organic chemistry an enol ether is an alkene with an alkoxy substituent. The general structure is R2C=CR-OR where R = H, alkyl or aryl. A common subfamily of enol ethers are vinyl ethers, with the formula ROCH=CH2. Important enol ethers include the reagent 3,4-dihydropyran and the monomers methyl vinyl ether and ethyl vinyl ether.

<span class="mw-page-title-main">Hot-melt adhesive</span> Glue applied by heating

Hot-melt adhesive (HMA), also known as hot glue, is a form of thermoplastic adhesive that is commonly sold as solid cylindrical sticks of various diameters designed to be applied using a hot glue gun. The gun uses a continuous-duty heating element to melt the plastic glue, which the user pushes through the gun either with a mechanical trigger mechanism on the gun, or with direct finger pressure. The glue squeezed out of the heated nozzle is initially hot enough to burn and even blister skin. The glue is sticky when hot, and solidifies in a few seconds to one minute. Hot-melt adhesives can also be applied by dipping or spraying, and are popular with hobbyists and crafters both for affixing and as an inexpensive alternative to resin casting.

Wood glue is an adhesive used to tightly bond pieces of wood together. Many substances have been used as glues. Traditionally animal proteins like casein from milk or collagen from animal hides and bones were boiled down to make early glues. They worked by solidifying as they dried. Later, glues were made from plant starches like flour or potato starch. When combined with water and heated, the starch gelatinizes and forms a sticky paste as it dries. Plant-based glues were common for books and paper products, though they can break down more easily over time compared to animal-based glues. Examples of modern wood glues include polyvinyl acetate (PVA) and epoxy resins. Some resins used in producing composite wood products may contain formaldehyde. As of 2021, “the wood panel industry uses almost 95% of synthetic petroleum-derived thermosetting adhesives, mainly based on urea, phenol, and melamine, among others”.

Polyvinyl nitrate (abbreviated: PVN) is a high-energy polymer with the idealized formula of [CH2CH(ONO2)]. Polyvinyl nitrate is a long carbon chain (polymer) with nitrate groups bonded randomly along the chain. PVN is a white, fibrous solid, and is soluble in polar organic solvents such as acetone. PVN can be prepared by nitrating polyvinyl alcohol with an excess of nitric acid. Because PVN is also a nitrate ester such as nitroglycerin (a common explosive), it exhibits energetic properties and is commonly used in explosives and propellants.

<span class="mw-page-title-main">Flubber (material)</span> Type of gelatin

Flubber, Glorp, Glurch, or Slime is a rubbery polymer formed by cross-linking of polyvinyl alcohol (PVA) with a borate compound. Slime can be made by combining polyvinyl-acetate-based adhesives with borax.

Isopropyl alcohol is a colorless, flammable organic compound with a pungent alcoholic odor.

<span class="mw-page-title-main">Chloroacetaldehyde</span> Chemical compound

Chloroacetaldehyde is an organic compound with the formula ClCH2CHO. Like some related compounds, it is highly electrophilic reagent and a potentially dangerous alkylating agent. The compound is not normally encountered in the anhydrous form, but rather as the hemiacetal (ClCH2CH(OH))2O.

A nanocapsule is a nanoscale shell made from a nontoxic polymer. They are vesicular systems made of a polymeric membrane which encapsulates an inner liquid core at the nanoscale. Nanocapsules have many uses, including promising medical applications for drug delivery, food enhancement, nutraceuticals, and for self-healing materials. The benefits of encapsulation methods are for protection of these substances to protect in the adverse environment, for controlled release, and for precision targeting. Nanocapsules can potentially be used as MRI-guided nanorobots or nanobots, although challenges remain.

<span class="mw-page-title-main">Intravitreal implants</span>

Intravitreal implants are micro device-like inserts injected into the posterior segment of the eye to treat retinal diseases releasing therapeutic drugs at a set rate over a desired period of time. The posterior segment of the eye consists of the sclera, choroid, fovea, vitreous humor, optic nerve, and retina.

References

  1. ↑ "Poly(vinyl alcohol)". ChemSrc.
  2. ↑ Schnepf MJ, Mayer M, Kuttner C, et al. (July 2017). "Nanorattles with tailored electric field enhancement". Nanoscale. 9 (27): 9376–9385. doi: 10.1039/C7NR02952G . hdl: 10067/1447970151162165141 . PMID   28656183.
  3. 1 2 3 4 5 Hallensleben ML (2000). "Polyvinyl Compounds, Others". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a21_743. ISBN   978-3527306732.
  4. ↑ Tang X, Alavi S (2011). "Recent Advances in Starch, Polyvinyl Alcohol Based Polymer Blends, Nanocomposites and Their Biodegradability". Carbohydrate Polymers. 85: 7–16. doi:10.1016/j.carbpol.2011.01.030.
  5. ↑ Adelnia, Hossein; Ensandoost, Reza; Shebbrin Moonshi, Shehzahdi; et al. (2022-02-05). "Freeze/thawed polyvinyl alcohol hydrogels: Present, past and future". European Polymer Journal. 164: 110974. doi:10.1016/j.eurpolymj.2021.110974. hdl: 10072/417476 . ISSN   0014-3057. S2CID   245576810.
  6. ↑ Baker MI, Walsh SP, Schwartz Z, Boyan BD (July 2012). "A review of polyvinyl alcohol and its uses in cartilage and orthopedic applications". Journal of Biomedical Materials Research Part B: Applied Biomaterials. 100 (5): 1451–7. doi:10.1002/jbm.b.32694. PMID   22514196.
  7. 1 2 SRI Consulting CEH Report Polyvinyl Alcohol, published March 2007, abstract retrieved July 30, 2008.
  8. ↑ Lampman, Steve, ed. (2003). "Effects of Composition, Processing, and Structure on Properties of Engineering Plastics". Characterization and Failure Analysis of Plastics. ASM International. p. 29. doi:10.31399/asm.tb.cfap.t69780028. ISBN   978-0-87170-789-5.
  9. ↑ Xu X, Zhao J, Wang M, et al. (August 2019). "3D Printed Polyvinyl Alcohol Tablets with Multiple Release Profiles". Scientific Reports. 9 (1): 12487. Bibcode:2019NatSR...912487X. doi:10.1038/s41598-019-48921-8. PMC   6713737 . PMID   31462744.
  10. ↑ "Contour™ - Brief Summary". www.bostonscientific.com. Retrieved 2023-08-11.
  11. ↑ Siskin GP. Cho KJ (ed.). "Uterine Fibroid Embolization and Imaging". Medscape. WebMD LLC. Archived from the original on 2015-03-04.
  12. ↑ Baker, Maribel I.; Walsh, Steven P.; Schwartz, Zvi; Boyan, Barbara D. (July 2012). "A review of polyvinyl alcohol and its uses in cartilage and orthopedic applications". Journal of Biomedical Materials Research Part B: Applied Biomaterials. 100B (5): 1451–1457. doi:10.1002/jbm.b.32694. PMID   22514196.
  13. ↑ Chaouat, Marc; Le Visage, Catherine; Baille, Wilms E.; Escoubet, Brigitte; Chaubet, Frédéric; Mateescu, Mircea Alexandru; Letourneur, Didier (2008-10-09). "A Novel Cross-linked Poly(vinyl alcohol) (PVA) for Vascular Grafts". Advanced Functional Materials. 18 (19): 2855–2861. doi:10.1002/adfm.200701261. S2CID   42332293.
  14. ↑ Kawai F, Hu X (August 2009). "Biochemistry of microbial polyvinyl alcohol degradation". Applied Microbiology and Biotechnology. 84 (2): 227–37. doi:10.1007/s00253-009-2113-6. PMID   19590867. S2CID   25068302.
  15. ↑ Byrne, Dominic, Boeije, Geert, Croft, Ian, Hüttmann, Gerd, Luijkx, Gerard, Meier, Frank, Parulekar, Yash and Stijntjes, Gerard. "Biodegradability of Polyvinyl Alcohol Based Film Used for Liquid Detergent Capsules: Biologische Abbaubarkeit der für Flüssigwaschmittelkapseln verwendeten Folie auf Polyvinylalkoholbasis." Tenside Surfactants Detergents, vol. 58, no. 2, 2021, pp. 88-96. https://doi.org/10.1515/tsd-2020-2326
  16. 1 2 DeMerlis, C. C.; Schoneker, D. R. (March 2003). "Review of the oral toxicity of polyvinyl alcohol (PVA)". Food and Chemical Toxicology. 41 (3): 319–326. doi:10.1016/s0278-6915(02)00258-2. ISSN   0278-6915. PMID   12504164 . Retrieved 17 January 2024.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.