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Polyvinyl alcohol (PVOH, PVA, or PVAl) is a water-soluble synthetic polymer.
Polyvinyl alcohol has the idealized formula [CH2CH(OH)]n.
Polyvinyl alcohol 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.
CAS: 9002-89-5
MF: C2H4O
MW: 44.05256
EINECS: 209-183-3
Synonyms
Polyvinyl alcohol, 98-99% hydrolyzed, high molecular weight;Poly(vinyl Alcohol) n=1750+/-50;Poly(vinyl Alcohol) n(=:)2,000 (degree's of saponification ca. 80mol%);POLYVINYL ALCOHOL 98-99% HYDROLYZED;POLYVINYL ALCOHOL 99% POWDER;POLYVINYL ALCOHOL USP/NF;Polyvinyl Alcohol, 88-89%;Polyvinyl Alcohol, 99-100%
Polyvinyl alcohol is colourless (white) and odorless.
Polyvinyl alcohol is commonly supplied as beads or as solutions in water.
Without an externally added crosslinking agent, Polyvinyl alcohol 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.
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 and sealer.
Polyvinyl alcohol is a homopolymer macromolecule obtained by polymerisation of vinyl alcohol.
Polyvinyl alcohol is used as a pharmaceutic aid and ophthalmic lubricant as well as in the manufacture of surface coatings artificial sponges, cosmetics, and other products.
Polyvinyl alcohol (PVOH) is a hydrophilic linear polymer which forms copolymers of vinyl alcohol and vinyl acetate.
Hence, the structural properties of polyvinyl alcohol polymers depend on the extent of polymerization and hydrolysis.
Such changes cause both chemical and physical modifications such as esterification, etherification, crystallization, ion-polymer complexation in the polymer.
Modified- PVOH structures are useful in biomedical applications.
Polyvinyl alcohol (PVOH, PVA, or PVAl) is a synthetic polymer which is both colourless, odourless and water-soluble.
Polyvinyl alcohol was initially discovered in the early 1920's and since has been used in numerous applications from the lamination of safety glass to the packaging of laundry detergents.
Polyvinyl alcohol is usually supplied as a powder, granules, or pellets, or sometimes as a solution in water.
Poly(vinyl alcohol) Chemical Properties
Melting point: >300 °C
Boiling point: -14.5°C (rough estimate)
bulk density: 400-670kg/m3
density: 1.080 g/cm3
Tg: 73
Tg: 99
Tg: 99°C
refractive index: 1.3810 (estimate)
Fp: 79°C
storage temp.: Store below +30°C.
solubility H2O: soluble (hot)
form: Powder
color: White to cream
PH: 3.5-7.0 (40g/l, H2O, 20℃)
Odor: at 100.00%. odorless
Water Solubility: soluble in hot water
Merck: 14,7585
Dielectric constant: 1.9（Ambient）
Stability: Stable. Combustible. Dust may form explosive mixtures with air. Incompatible with strong oxidizing agents.
Cosmetics Ingredients Functions: FILM FORMING
VISCOSITY CONTROLLING
InChI: 1S/C2H4O/c1-2-3/h2-3H,1H2
InChIKey: IMROMDMJAWUWLK-UHFFFAOYSA-N
IARC: 3 (Vol. 19, Sup 7) 1987
NIST Chemistry Reference: Polyvinyl alcohol(9002-89-5)
EPA Substance Registry System: Polyvinyl alcohol (9002-89-5)
Polyvinyl alcohol is a hydrolysis product of polyvinyl acetate, rather than by the polymerization of monomers; the molecular backbone contains Polyvinyl alcohol.
The specific gravity of this product 1.25 to 1.35 and the melting point is 212 ~ 267 ℃.
Polyvinyl alcohol is soluble in hot water and hot dimethyl sulfoxide.
Animal experiments show that polyvinyl alcohol, without stimulation, causes no significant toxicity upon subcutaneous, intramuscular, intravenous injection.
Polyvinyl alcohol resin products appear as white solid with the appearance of sub-floc, granular and powder; it is non-toxic, tasteless, non-polluting and is soluble in water of 80--90 ℃.
Polyvinyl alcohol's aqueous solution has good adhesiveness and film-forming property; it can resist most organic solvents such as oils, lubricants and hydrocarbons; it has long-chain polyol esterification, etherification, acetalization and other chemical properties.
Structure and properties
Polyvinyl alcohol 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.
Polyvinyl alcohol has excellent film-forming, emulsifying and adhesive properties.
Polyvinyl alcohol is also resistant to oil, grease and solvents.
Polyvinyl alcohol 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.
Uses
Polyvinyl alcohol is safe and environmentally friendly.
Beyond the popular laundry and detergent packets, it is used in many household, medical, personal care and industrial applications, including food packaging, textile yarns, paper products, unit- dose pharmaceuticals, water treatment chemicals, “artificial tears” used to treat dry eyes, contact lens lubricants, transfer printing, agrochemicals, embroidery and dust abatement.
Food-grade versions of the film are used to deliver pre-measured quantities of rice, pasta, cocoa seasoning and nutritional supplements.
For example, in the US market, the material is being used to create packets that contain doses of whey protein powder, favoured by fitness enthusiasts for building lean muscle mass.
The pre-measured packets make it easier and more convenient to simply drop the protein into a shaker bottle with water or milk, mix and drink.
This ensures the correct amount of protein is used with no waste or mess.
Other grades of Polyvinyl alcohol film are used in manufacturing processes, such as mould release film in the production of solid surface countertops and reinforced composites
Mowiol 40-88 can be used for a variety of applications such as drug delivery, surface enhanced Raman spectroscopy (SERS) fiber-optic sensors, and transparent conducting oxides (TCOs).
In the plastics industry in molding Compounds, surface coatings, films resistant to gasoline, textile sizes and finishing compositions; can be compounded to yield elastomers to be used in manufacture of artificial sponges, fuel hoses, etc., also in printing inks for plastics and glass, in pharmaceutical finishing, cosmetics, water-sol film and sheeting.
Pharmaceutic aid (viscosity increasing agent); ophthalmic lubricant.
NaA zeolite particles have been dispersed in a poly(vinyl alcohol) matrix to prepare a mixed-matrix membrane to study the pervaporative separation of water-butanol mixtures.
Poly (vinyl alcohol)/gelatin based biocompatible polymeric scaffolds have been used to design for 3D cancer models.
Polyvinyl alcohol is mainly used in the textile industry, as the raw materials of warp pulp, fabric finishing agent, vinylon fiber; interior and exterior wall paint of the building, adhesives; chemical industry use Polyvinyl alcohol as a polymerization emulsifier, dispersant and polyvinyl formal, acetal, butyrate aldehyde resin; paper industry use it as a paper binder; agriculture use Polyvinyl alcohol as soil improvers, pesticide adhesion synergist and polyvinyl alcohol film; it can also be used for daily cosmetics and high-frequency quenching agent and so on.
Polyvinyl alcohol 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, laundry detergent pods and eye drops.
Polyvinyl alcohol is used as an aid in suspension polymerizations.
Polyvinyl alcohol's 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.
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.
Polyvinyl alcohol-based polymers are used widely in additive manufacturing.
For example, 3D printed oral dosage forms demonstrate great potential in the pharmaceutical industry.
Polyvinyl alcohol is possible to create drug-loaded tablets with modified drug-release characteristics where PVA is used as a binder substance.
Medically, Polyvinyl alcohol-based microparticles have received FDA 510(k) approval to be used as embolisation particles to be used for peripheral hypervascular tumors.
Polyvinyl alcohol may also used as the embolic agent in a Uterine Fibroid Embolectomy (UFE).
In biomedical engineering research, Polyvinyl alcohol has also been studied for cartilage, orthopaedic applications, and potential materials for vascular graft.
Polyvinyl alcohol is commonly used in household sponges that absorb more water than polyurethane sponges.
Polyvinyl alcohol may be used as an adhesive during preparation of stool samples for microscopic examination in pathology.
Pharmaceutical Applications
Polyvinyl alcohol is used primarily in topical pharmaceutical and ophthalmic formulations.
Polyvinyl alcohol is used as a stabilizing agent for emulsions (0.25–3.0% w/v).
Polyvinyl alcohol is also used as a viscosity-increasing agent for viscous formulations such as ophthalmic products.
Polyvinyl alcohol is used in artificial tears and contact lens solutions for lubrication purposes, in sustained-release formulations for oral administration, and in transdermal patches.
Polyvinyl alcohol may be made into microspheres when mixed with a glutaraldehyde solution.
Industrial uses
Polyvinyl alcohol is a tough, whitish polymerthat can be formed into strong films, tubes, andfibers that are highly resistant to hydrocarbonsolvents.
Although polyvinyl alcohol is one ofthe few water-soluble polymers, it can be renderedinsoluble in water by drawing or by theuse of cross-linking agents.
Polyvinyl acetals
Polyvinyl acetals are prepared by treating Polyvinyl alcohol 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, Polyvinyl alcohol 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, Polyvinyl alcohol is prepared by hydrolysis of polyvinyl acetate, 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.
Production Methods
Polyvinyl alcohol is produced through the hydrolysis of polyvinyl acetate.
The repeating unit of vinyl alcohol is not used as the starting material because it cannot be obtained in the quantities and purity required for polymerization purposes.
The hydrolysis proceeds rapidly in methanol, ethanol, or a mixture of alcohol and methyl acetate, using alkalis or mineral acids as catalysts.
Reactivity Profile
Mixtures of alcohols with concentrated sulfuric acid and strong hydrogen peroxide can cause explosions.
Example: an explosion will occur if dimethylbenzylcarbinol is added to 90% hydrogen peroxide then acidified with concentrated sulfuric acid.
Mixtures of ethyl alcohol with concentrated hydrogen peroxide form powerful explosives.
Mixtures of hydrogen peroxide and 1-phenyl-2-methyl propyl alcohol tend to explode if acidified with 70% sulfuric acid.
Alkyl hypochlorites are violently explosive.
They are readily obtained by reacting hypochlorous acid and alcohols either in aqueous solution or mixed aqueous- carbon tetrachloride solutions.
Chlorine plus alcohols would similarly yield alkyl hypochlorites.
They decompose in the cold and explode on exposure to sunlight or heat.
Tertiary hypochlorites are less unstable than secondary or primary hypochlorites.
Base-catalysed reactions of isocyanates with alcohols should be carried out in inert solvents. Such reactions in the absence of solvents often occur with explosive violence.
