What Is Polyvinylpyrrolidone (PVP)?
Polyvinylpyrrolidone (PVP), also called povidone or polyvidone, is a water-soluble, film-forming vinyl polymer made from N-vinylpyrrolidone (NVP). CAS 9003-39-8 covers the linear (non-crosslinked) PVP homopolymer. It is valued for an unusual combination of properties: it dissolves in both water and many polar organic solvents, forms clear films, adheres well to many surfaces, is non-ionic and pH-stable, and is classed as low-toxicity.
PVP is supplied in a range of grades defined by K-value, which reflects molecular weight. This guide covers the chemistry, production, grades and specification, properties, applications, comparison with other binders, K-value selection, safety and supply. PolyBlueChem supplies PVP K90 (technical grade) to the specification below with per-batch COA and SDS.
| CAS number | 9003-39-8 (linear PVP homopolymer) |
| Synonyms | Polyvinylpyrrolidone; PVP; povidone; polyvidone; 1-vinyl-2-pyrrolidinone homopolymer |
| Molecular formula | (C6H9NO)n |
| Monomer | N-vinylpyrrolidone (NVP), CAS 88-12-0 |
| Appearance | White to yellowish-white hygroscopic powder |
| Grades | Defined by K-value (K12 to K90) and by use (technical, cosmetic, pharmaceutical) |
Chemistry and Structure
PVP is a linear polymer whose repeating unit is the N-vinylpyrrolidone (NVP) residue. Each unit carries a lactam (amide) group, which is polar and capable of hydrogen bonding, on a non-polar carbon backbone. This gives PVP its amphiphilic character – it is compatible with water and with many organic solvents, and it can bind to a wide variety of substrates.
Two structural points matter commercially:
- Linear vs crosslinked – CAS 9003-39-8 is linear PVP (soluble). Crosslinked PVP (crospovidone) is a different material and a different CAS; it is insoluble and used as a disintegrant. They are not interchangeable.
- Molecular weight (K-value) – the same repeat unit can be polymerised to very different chain lengths. Chain length sets viscosity, film strength, adhesion and solution behaviour, and it is the main way PVP grades are distinguished.
The lactam group is also why PVP is a good complexing agent – it binds small molecules (the best-known example being the iodine complex used in disinfectants) and helps solubilise or stabilise active ingredients.
How PVP Is Produced
PVP is made in two stages: first the monomer NVP is synthesised, then NVP is polymerised under controlled conditions to the target molecular weight.
| Stage | Principle |
|---|---|
| Monomer (NVP) synthesis | NVP is produced from acetylene and formaldehyde via butynediol and 2-pyrrolidone chemistry. Modern routes focus on a clean, low-residue monomer because residual NVP must be minimised in the final polymer. |
| Polymerisation | NVP is polymerised by free-radical polymerisation in water or an alcohol (often isopropanol), using an initiator such as hydrogen peroxide or an azo/peroxide initiator. Reaction temperature, solvent and chain-transfer conditions control molecular weight and therefore the K-value. |
| Finishing | The polymer solution is dried (spray or drum drying), milled and sieved to a powder, and the residual monomer, water and ash are controlled to specification. |
Because the K-value is set mainly by the polymerisation step, the same plant can produce the whole K-series by changing the reaction conditions. Technical grade is finished to the specification below; cosmetic and pharmaceutical grades are finished and tested to tighter monographs.
Grades and K-Values
PVP grades are named by K-value. The K-value is a viscosity-derived measure of molecular weight: higher K means a longer chain, higher solution viscosity and stronger binding. The molecular weights below are indicative approximations used for orientation, not exact figures.
| Grade | Approximate molecular weight | Character | Typical use |
|---|---|---|---|
| K12 | about 2,500 | Very low viscosity | Solubiliser, dispersant |
| K17 | about 10,000 | Low viscosity | Film former, ophthalmic and cosmetic |
| K25 | about 25,000 | Low-medium | Coatings, cosmetic |
| K30 | about 50,000 | Medium (workhorse grade) | Binders, adhesives, coatings, cosmetic, pharma |
| K60 | about 400,000 | High | Thickening, strong binders |
| K90 | about 1,000,000 – 1,500,000 | Very high viscosity | Strong binders, thickeners, film strength |
K90 (the grade supplied here) is the high-molecular-weight type. It is chosen when strong binding, high viscosity or tough, cohesive films are needed, and where a lower K-grade would be too thin.
Specifications
PVP K90 technical grade is supplied to the following specification:
| Parameter | Specification |
|---|---|
| Appearance | White or yellowish-white hygroscopic powder |
| Identification | A, B, C, D |
| pH | 4.0 – 9.0 |
| Appearance of solution | Clear solution |
| K-Value | 87.4 – 94.2 (nominal K90) |
| Vinylpyrrolidone (NVP) residual monomer | 0.1% max |
| Water | 5.0% max |
| Residue on ignition | 0.1% max |
| Nitrogen content | 11.5 – 12.8% |
The K-value (87.4 – 94.2) fixes the molecular-weight band – and therefore the viscosity and binding strength – of the batch. The NVP limit (0.1% max) controls residual monomer, a key purity and safety parameter. Residue on ignition (0.1% max) limits inorganic salts, water (5.0% max) limits moisture in this hygroscopic powder, and nitrogen content (11.5 – 12.8%) confirms the polymer composition. A specification sheet and a per-batch certificate of analysis (COA) are available on request.
Key Properties
| Property | Behaviour | Practical value |
|---|---|---|
| Solubility | Soluble in water and many polar organic solvents | Formulate in water or solvent systems |
| Film formation | Forms clear, tough films | Coatings, adhesives, hair fixatives |
| Adhesion | Bonds to many substrates | Binder for pigments, electrodes, ceramics |
| Ionic character | Non-ionic and pH-stable | Compatible with a wide range of additives |
| Complexing | Binds small molecules | Solubilisation and stabilisation |
| Hygroscopicity | Absorbs moisture from air | Store sealed and dry |
| Binding strength | Increases strongly with K-value | K90 for maximum cohesion |
The combination of water-plus-solvent solubility, clear film formation and strong adhesion is what sets PVP apart from binders such as PVA or starch: PVP can be used in both aqueous and mixed-solvent systems without a change of binder.
Applications
PVP K90 (technical grade) is used wherever a strong, soluble binder, film former or thickener is required.
| Industry | Function |
|---|---|
| Adhesives and binders | Film-forming binder in glues, remoistenable and hot-melt adhesives; viscosity builder |
| Coatings and inks | Pigment dispersant, film former and rheology modifier |
| Electronics | Binder/dispersant in photoresists, conductive pastes, capacitor and electrode formulations |
| Ceramics and refractory | Green (pre-sinter) binder that burns out cleanly |
| Detergents and cleaning | Dye-transfer inhibitor, thickener, soil-release aid |
| Personal care | Film former and fixative in hair and styling products |
| Textile and paper | Sizing, coating and finishing aid |
| Agrochemicals | Dispersant and granulation binder |
- Adhesives and coatings – K90’s high molecular weight gives cohesive, tacky films and good adhesion (see PVP K90 in adhesives and coatings).
- Electronics and ceramics – used as a binder and dispersant where clean burn-out and even films are needed (see PVP K90 in electronics and ceramics).
- Detergents and personal care – the dye-transfer and film-forming roles that use the polymer’s affinity for dyes and surfaces (see PVP in detergents and personal care).
PVP vs Other Binders and Polymers
PVP is often compared with polyvinyl alcohol (PVA), cellulose ethers (HPMC/CMC), starch and acrylic binders. The choice turns on solubility range, film quality, adhesion and cost.
| Binder | Water-soluble | Organic-soluble | Film / adhesion | Notes |
|---|---|---|---|---|
| PVP | Yes | Many polar solvents | Clear, strong, good adhesion | Non-ionic, complexing, higher cost |
| PVA | Yes | Limited | Strong, flexible films | Water-based only; lower cost |
| HPMC / CMC | Yes | No | Good film, thickener | Cellulosic; water-based |
| Starch | Yes (gelatinised) | No | Cheaper, weaker film | Low cost, lower performance |
| Acrylic binders | Some | Some | Tunable, durable | Different chemistry and cure |
Choose PVP where you need both water and solvent compatibility, clear films, strong adhesion or complexing; choose PVA, HPMC or starch where a purely aqueous, lower-cost binder will do.
K-Value Selection
Once PVP is the right chemistry, the K-value sets the performance. Use the guide below as a starting point and confirm on your own formulation.
| Requirement | Suggested grade |
|---|---|
| Low viscosity, solubilisation | K12 – K17 |
| General binder / film former | K30 |
| Higher viscosity and hold | K60 |
| Maximum binding, thickening and film strength | K90 |
Higher K means a more viscous solution at the same solids, so a K90 solution must be run at lower solids than a K30 to stay workable – the trade-off for its greater binding strength. For a fuller comparison see PVP K-value grades: selection guide.
Dosage and Formulation Notes
PVP is used at levels set by the application; the figures below are orientation only.
| Application | Starting-point guidance |
|---|---|
| Adhesive / binder | A few percent to a few tens of percent of the dry formulation, set by the required tack and film strength |
| Coating / ink | Low percentages as a dispersant/film former, adjusted for viscosity |
| Ceramic green binder | Small addition to the body, set by green strength and burn-out |
| Detergent / cleaning | Fraction of a percent as dye-transfer inhibitor, by test |
Because a K90 solution is viscous, prepare stock solutions at modest solids and add under good agitation. Confirm the level and the solution solids on your own system.
Working with PVP Solutions
PVP is usually used as a solution, so how it is dissolved and handled affects performance.
- Dissolving – add the powder to water or solvent under good agitation. Because K90 is high-viscosity, prepare stock solutions at modest solids (for example 5 – 15%) and let the polymer wet out fully; lumps formed by poor wetting dissolve slowly.
- Viscosity – solution viscosity rises steeply with concentration and with K-value. A K90 solution is far more viscous than a K30 solution at the same solids, so work at lower solids for high K.
- Solvent choice – PVP dissolves in water and in many polar organic solvents, so the same grade can be used in aqueous and mixed-solvent systems; confirm compatibility with your specific solvent blend.
- Stability – PVP is non-ionic and pH-stable over a wide range, and is generally compatible with common additives; as a hygroscopic polymer it should be stored and, where possible, used to avoid excess moisture pickup.
- Film properties – PVP films are clear and adhesive but can be moisture-sensitive; where water resistance is needed, blend with a more hydrophobic binder or a crosslinker.
Reading a PVP Certificate of Analysis
Each line of the specification controls a different aspect of quality; the table explains what to look at on a batch COA.
| Parameter | What it controls | Why it matters |
|---|---|---|
| K-Value | Molecular weight / viscosity | Sets binding strength and solution viscosity – the key grade parameter |
| Vinylpyrrolidone (NVP) | Residual monomer | Purity and safety control |
| Water | Moisture | Hygroscopic powder; affects weighing and storage |
| Residue on ignition | Inorganic salts/ash | Limits process residues |
| Nitrogen content | Polymer composition | Confirms the polymer identity |
| pH | Acidity/alkalinity of the solution | Compatibility in formulation |
| Appearance of solution | Insoluble matter | Clarity for films and coatings |
| Identification | Identity tests A, B, C, D | Confirms the material is PVP |
Safety, Handling and Storage
- Low toxicity – PVP has a long history of pharmaceutical and cosmetic use; the residual NVP limit (0.1% max) is the main safety control because the monomer is more hazardous than the polymer.
- Dust – fine powder can cause mild mechanical irritation; use dust control where large amounts are handled.
- Hygroscopic – the powder absorbs moisture; keep containers sealed and store cool and dry, away from heat.
- Spills – slippery when wet; clean up with water and prevent entry to drains.
Regulatory Status
| Use | Status (as commonly cited) |
|---|---|
| Pharmaceutical | Povidone is a long-established excipient (USP/EP monographs); supplied here is technical grade, not pharma grade |
| Cosmetic | Widely used and permitted in many markets as a film former/fixative |
| Industrial / technical | Governed by the specification and by the buyer’s requirements |
Grade must match the end use: technical grade should not be substituted for pharmaceutical or cosmetic grade without checking the applicable monograph. Confirm the required grade and documentation for your market with us.
Sourcing and Market Notes
PVP is a specialty polymer rather than a bulk commodity, so grade, K-value and documentation matter more than price alone.
- Match the grade to the use – technical, cosmetic and pharmaceutical grades share the chemistry but differ in finishing and testing. Buy the grade the end use requires and check the certificate.
- Confirm the K-value – because viscosity and binding strength track the K-value, state the target K-band (here 87.4 – 94.2) and check it on each batch COA.
- Cost drivers – NVP monomer, polymerisation and drying energy, and the finishing to the required residual-monomer level. Higher-K grades and tighter grades cost more.
- Packaging and freight – supplied as a hygroscopic powder in 25 kg bags or drums; keep sealed and dry in transit and storage, and allow for moisture protection on long sea routes.
- Supply planning – order against forecast and store cool and dry; because the powder picks up moisture, good housekeeping protects the K-value performance you paid for.
Packaging, Logistics and Supply
| Item | Standard options |
|---|---|
| Packaging | 25 kg PP/PE bags or fibre drums |
| Documentation | Per-batch COA and SDS; other certificates on request |
| Incoterms | FOB and CIF |
| Storage | Sealed, cool and dry (hygroscopic powder) |
For buying and quality checks see how to buy PVP K90.
Frequently Asked Questions about PVP
What is the CAS number of PVP?
Linear polyvinylpyrrolidone is CAS 9003-39-8. The monomer NVP is CAS 88-12-0. Crosslinked PVP (crospovidone) is a different material.
What does the K-value mean?
The K-value is a viscosity-based measure of molecular weight. Higher K means a longer chain, higher viscosity and stronger binding; K90 is a high-molecular-weight grade.
Is PVP K90 the same as povidone?
Povidone is a synonym for PVP. K90 is a specific grade of povidone/PVP.
Is technical grade the same as pharmaceutical grade?
No. They share the chemistry but differ in how they are finished and tested. This product is technical grade; do not substitute it for a pharmaceutical or cosmetic grade without checking the monograph.
Why is residual NVP limited?
Because the residual monomer is more hazardous than the polymer, so the specification caps NVP at 0.1% max.
How should PVP be stored?
Sealed, cool and dry – it is hygroscopic and absorbs moisture from the air.
What is the difference between K30 and K90?
K30 is a medium molecular weight general-purpose grade; K90 is much higher, giving stronger binding, higher viscosity and tougher films.
Related reading
- PVP K90 in adhesives and coatings
- PVP K90 in electronics and ceramics
- PVP K-value grades: selection guide
- How to buy PVP K90
- PVP in detergents and personal care
- Polyvinylpyrrolidone (PVP K90), CAS 9003-39-8 – product page
PolyBlueChem supplies PVP K90 (polyvinylpyrrolidone, CAS 9003-39-8, technical grade) to this specification, with per-batch COA and SDS and FOB/CIF delivery. Contact us with your application, tonnage and delivery port.