1. PolyDADMAC (CAS 26062-79-3): An Overview
Poly(diallyldimethylammonium chloride), commonly known as PolyDADMAC (also abbreviated as PDADMAC or PDMDAAC), is a water-soluble cationic polyelectrolyte of considerable importance across many industries. The polymer is formed from the monomer diallyldimethylammonium chloride (DADMAC) and has the repeating unit (C8H16NCl)n, with molecular weights ranging from low (about 100,000) to high (up to roughly 1,000,000) depending on grade.
What makes PolyDADMAC valuable is the combination of a permanently charged quaternary ammonium group in every repeat unit and a water-soluble polymer backbone. The result is a polymer with a high, pH-independent positive charge density that neutralises negatively charged particles in water – the basis of its role as a primary coagulant, flocculant, fixative and charge-control agent. It is used most heavily in water and wastewater treatment, pulp and paper, oilfield operations, textiles, mining and personal care.
This article reviews the chemistry, charge behaviour, synthesis, grades, applications and procurement of PolyDADMAC from the perspective of a supplier and industrial user.
2. Chemical and Physical Properties
| Property | Typical value |
|---|---|
| Chemical name | Poly(diallyldimethylammonium chloride) |
| Abbreviations | PolyDADMAC / PDADMAC / PDMDAAC |
| CAS Registry Number | 26062-79-3 |
| Monomer | Diallyldimethylammonium chloride (DADMAC), CAS 7398-69-8 |
| Repeat unit | (C8H16NCl)n |
| Appearance (liquid) | Colourless to light-yellow viscous liquid |
| Appearance (powder) | White to light-yellow beads or flakes |
| Charge type | Permanently cationic (quaternary ammonium), pH-independent |
| Charge density | Typically about 5 to 6 meq/g (dry basis) |
| Solubility | Fully water-soluble; soluble in polar solvents |
| Density (solution) | About 1.03 to 1.09 g/cm3 at 20-25 °C |
| Viscosity | Varies with concentration and molecular weight; typically 60-180 cP for ~20 wt% solutions, higher for high-viscosity grades |
| Refractive index | About 1.375 to 1.417 depending on concentration and grade |
| Thermal stability | Stable; decomposition typically above about 280 °C |
| Flash point | Above 100 °C (low flammability) |
2.1 Physical form and solubility
In liquid form PolyDADMAC is a colourless to light-yellow viscous solution with a degree of freeze protection depending on grade; in powder form it is supplied as white to light-yellow beads or flakes that dissolve readily in water. Both forms are non-flammable and hydrolytically stable.
2.2 Density, viscosity and optical properties
The density of aqueous solution grades sits in roughly the 1.03-1.09 g/cm3 range at 20-25 °C. Viscosity depends strongly on both concentration and molecular weight, which is why viscosity grade is one of the key specification parameters for buyers. Refractive index varies with concentration and grade.
2.3 Chemical stability and safety
PolyDADMAC is generally stable: it resists hydrolysis and oxidation across a broad pH range, is resistant to chlorine under typical use conditions, and has low flammability (flash point above 100 °C). As a cationic polymer it carries a high positive charge density, which is the origin of its coagulation and flocculation behaviour. It should be stored in sealed, cool, dry, dark conditions away from strong oxidants. While generally of low toxicity, normal handling precautions (gloves, eye protection, dust mask for powder) are recommended.
3. Charge Density and Coagulation Mechanism
The core of PolyDADMAC’s performance is its charge density. Every repeat unit carries a quaternary ammonium group that is positively charged over essentially the whole practical pH range. This is different from many other cationic polymers – such as polyamines or cationically modified polyacrylamides – whose charge depends on pH because it arises from protonated amines. The practical consequence is that PolyDADMAC keeps working in acidic, neutral and alkaline water alike.
When added to water containing suspended particles, two mechanisms operate:
- Charge neutralisation. The polymer’s positive charges neutralise the negative surface charges on colloids such as clay, silt, algae, bacteria, viruses, colour bodies and dye molecules, reducing the electrostatic barrier that keeps them apart.
- Bridging and floc formation. Because each polymer chain carries many charges, it can adsorb onto several particles at once, binding them into larger aggregates (flocs) that settle, float or filter out. Medium-molecular-weight PolyDADMAC is particularly effective in this bridging role, which is why molecular weight is matched to the application.
Because it is a primary coagulant rather than only a flocculant aid, PolyDADMAC is often used on its own in low-turbidity waters, or in combination with inorganic coagulants such as polyaluminium chloride (PAC) where a dual-coagulant programme is appropriate.
4. Synthesis and Polymerization
4.1 Monomer synthesis
DADMAC monomer is made by reacting dimethylamine with two equivalents of allyl chloride. The resulting ammonium monomer is water-soluble and readily polymerised.
4.2 Polymerization process
PolyDADMAC is produced by free-radical polymerization of the DADMAC monomer, typically initiated with an organic peroxide or a water-soluble azo/redox initiator in aqueous solution. During polymerization the monomer cyclises, preferentially forming a five-membered N-substituted pyrrolidinium ring in the backbone rather than a six-membered piperidine ring. The reaction is run under controlled temperature and monomer feed to reach the target molecular weight and viscosity grade.
| Process step | Key inputs / controls | Effect on product |
|---|---|---|
| Monomer formation | Dimethylamine + allyl chloride | Determines monomer purity, which carries through to the polymer |
| Free-radical polymerization | Initiator, temperature, monomer feed, chain-transfer control | Sets molecular weight and viscosity grade |
| Cyclization | Reaction conditions | Favours the pyrrolidinium backbone that gives the rigid, high-charge polymer |
| Finishing | Concentration, pH adjustment, or drying to powder | Defines the commercial liquid or powder grade |
Molecular weights range from low (about 100,000) to higher grades in the region of 200,000 to 1,000,000, depending on polymerization conditions. This range is what allows suppliers to offer a family of grades matched to different duties.
5. Grades, Forms and Specifications
| Grade dimension | Typical options | Where it is used |
|---|---|---|
| Physical form | Liquid solution or dry powder (beads/flakes) | Liquid for easy dosing; powder for transport and low-water formulations |
| Molecular weight | Low (about 100,000) to high (up to about 1,000,000) | Lower Mw for coagulant/charge roles; higher Mw for bridging and dewatering |
| Solid content (liquid) | Commonly about 20 to 40% | Set by dosing equipment and freight economics |
| Charge density | Typically about 5 to 6 meq/g (dry basis) | Normally fixed by the chemistry; not a pH-dependent variable |
| Application grade | Water-treatment grade (e.g. NSF/ANSI 60 compliant) or industrial grade | Drinking water and food-related uses require the compliant grade |
Buyers should confirm form, solid content or dry content, viscosity, molecular-weight range and the applicable regulatory grade, because the same “PolyDADMAC” name covers a family of products whose performance differs with grade.
6. Industrial Applications
PolyDADMAC is used across a broad range of industries because of its cationic nature, high charge density and stability. The main sectors and roles are summarised below and then described in detail.
6.1 Water and wastewater treatment
Primary coagulant / flocculant. PolyDADMAC neutralises negatively charged colloidal particles (silt, clay, algae, bacteria, viruses) and bridges them into flocs, improving clarity in both drinking water and industrial wastewater treatment.
Sludge dewatering. The polymer aids sludge-volume reduction and improves the efficiency of water separation and filtration.
Removal of natural organic matter. At suitable doses it removes humic and fulvic acids, lowering colour and helping to reduce disinfection by-product precursors.
Textile dye wastewater decolorisation. It is used to decolourise and flocculate dye-house effluent, with good performance against reactive, acid and disperse dyes.
6.2 Pulp and paper industry
- Improves retention and drainage, promoting removal of fines and fillers.
- Enhances disc filter, flotation and filler cationisation performance, improving sheet strength and machine efficiency.
- Provides fixing action, binding pitch from mechanical pulp and latex from recycled fibre (“anionic trash catcher”), improving product quality.
6.3 Oilfield and drilling
- Clay stabiliser in drilling and completion fluids.
- Cationic modifier in acid fracturing and water-injection processes.
- Supports oil-water separation and improves efficiency in hydrocarbon recovery.
6.4 Textiles and dye fixing
PolyDADMAC is used as a formaldehyde-free fixing agent that improves dye adherence in textile finishing while avoiding formaldehyde emissions.
6.5 Personal care and cosmetics
It serves as a conditioning agent, antistatic agent and humectant in shampoos and skin lotions, improving texture and reducing static, and is often described as formaldehyde-free.
6.6 Other industrial uses
- Emulsifier, antistatic agent or surface-active component in various chemical formulations.
- Mineral processing flocculant in mining (coal, gold, diamonds) for solid-liquid separation.
- Sugar and juice refining as a decolourant.
- Coatings and inks for colour binding, anti-corrosion or polymer-bridging effects.
6.7 Nanotechnology, sensors and biomedical research
- Stabilises nanoparticles (for example copper hexacyanoferrate), preventing aggregation and controlling size distribution.
- Acts as a substrate modifier in biosensor and chemical-sensor fabrication (for example modifying indium tin oxide or catalyst platforms).
- Is studied in drug-delivery research, for example coating gold nanorods or forming responsive carriers with mesoporous silica.
7. Application and Dosage Guide
| Application | Typical role | Typical dose range |
|---|---|---|
| Drinking water | Primary coagulant / flocculant | About 0.2 to 1.5 ppm |
| Industrial effluent (e.g. textile dye wastewater) | Coagulant, decolourisation | Roughly 3 to 30 ppm |
| Sludge dewatering | Conditioning aid | Set by jar/bench testing |
| Pulp and paper | Retention, drainage and fixing aid | Set by mill trial |
Doses are indicative only: the optimum for any given water is normally established by jar testing, because turbidity, charge demand and competing anions all shift the required dose.
8. Summary Table
| Aspect | Key highlights |
|---|---|
| Formula / CAS | (C8H16NCl)n; CAS 26062-79-3; synonyms PDADMAC, PDMDAAC |
| Physical forms | Liquid (viscous, pale yellow) and powder (beads/flakes) |
| Density / viscosity | About 1.03-1.09 g/cm3; viscosity depends on concentration and molecular weight |
| Stability | Hydrolytically and thermally stable, chlorine-resistant, effective over a wide pH range |
| Synthesis | Free-radical polymerization of DADMAC (made from allyl chloride + dimethylamine) |
| Charge and mechanism | Permanently cationic, high charge density; charge neutralisation plus bridging |
| Key applications | Water and wastewater treatment, sludge dewatering, dye decolourisation, pulp and paper, textile dye fixation, oilfield, personal care, mining, sugar refining, nanoparticle stabilisation and sensors |
9. Quality, Standards and Regulatory Notes
Because much of the demand for PolyDADMAC comes from drinking-water and food-adjacent applications, the applicable grade matters as much as the physical specification. Water-treatment grades are commonly manufactured to comply with NSF/ANSI 60 (drinking water treatment chemicals) and are supported by documentation that industrial and municipal buyers can audit.
A typical quality package for a PolyDADMAC lot covers solids or active content, viscosity (and the temperature at which it is measured), pH, appearance, density and, for water grades, residual monomer content. Buyers should confirm both the parameter and the test method, because viscosity grades in particular are only meaningful when the concentration and temperature are stated.
10. Procurement: Packaging, Documentation and Selection
| Consideration | What to confirm |
|---|---|
| Form | Liquid solution or powder, depending on your dosing and storage |
| Active / solids content | Stated on the COA (commonly about 20 to 40% for liquids) |
| Viscosity | Grade and the temperature at which viscosity is measured |
| Molecular weight | Range suited to coagulant or bridging duty |
| Regulatory grade | NSF/ANSI 60-compliant water grade where required |
| Packaging | Drums, IBCs or bulk; powder in bags/drums as agreed |
| Documentation | COA, SDS and, for water grades, supporting regulatory documents |
| Storage and shelf life | Sealed, cool, dry, dark storage away from oxidants; retest period per COA |
11. Conclusion
Poly(diallyldimethylammonium chloride) is a versatile cationic polyelectrolyte valued for its stability, high pH-independent charge density and adaptability across a wide range of industrial processes. From its role as a key coagulant in water and wastewater treatment, to improving paper retention, enabling textile dye fixation, supporting oilfield and mining operations, enhancing personal care products, and underpinning research in nanotechnology, sensors and drug delivery, PolyDADMAC is a cornerstone polymer.
The ability to tailor its molecular weight, viscosity and physical form allows manufacturers to align the polymer precisely with application requirements, and its formaldehyde-free nature and regulatory compatibility further support its industrial appeal.
12. Frequently Asked Questions about PolyDADMAC
What is PolyDADMAC?
PolyDADMAC (poly(diallyldimethylammonium chloride), CAS 26062-79-3) is a water-soluble cationic polyelectrolyte made by the free-radical polymerization of diallyldimethylammonium chloride (DADMAC). It is used mainly as a primary coagulant and flocculant in water and wastewater treatment.
Why is PolyDADMAC an effective coagulant?
Its quaternary ammonium groups give it a high, pH-independent positive charge density (typically about 5 to 6 meq/g), so it neutralises negatively charged colloids such as clay, silt, algae, bacteria and dye molecules, and bridges them into flocs that settle or filter out.
What is the difference between PolyDADMAC, polyamine and PAM?
All three are organic flocculants. PolyDADMAC is a high-charge-density cationic polymer used as a primary coagulant, polyamine is a lower-molecular-weight cationic coagulant, and polyacrylamide (PAM) comes in anionic, cationic and nonionic forms and acts mainly as a bridging flocculant. See our Polyamine vs PAM vs PolyDADMAC comparison.
What dosage of PolyDADMAC is used?
Typical dosages are about 0.2 to 1.5 ppm for drinking water and roughly 3 to 30 ppm for industrial effluents such as textile dye wastewater. The optimum is normally set by jar testing on the actual water.
Is PolyDADMAC approved for drinking water treatment?
Water-treatment grades are used in drinking water and are commonly manufactured to comply with NSF/ANSI 60. See our article on PolyDADMAC in drinking water treatment.
Liquid or powder form?
PolyDADMAC is supplied both as a viscous aqueous solution (commonly about 20 to 40% solids) and as white to light-yellow beads or flakes for users who prefer a dry product.
Is PolyDADMAC charge affected by pH?
No. Because the charge comes from quaternary ammonium groups, it is essentially pH-independent, which is a practical difference from polyamines whose charge depends on pH.
How does PolyDADMAC differ from inorganic coagulants?
PolyDADMAC is an organic, pre-formed cationic polymer, so it works mainly by charge neutralisation and bridging and produces less sludge than many inorganic coagulants. It is often used alongside an inorganic coagulant such as polyaluminium chloride in dual-coagulant programmes.
Where can I buy PolyDADMAC?
PolyBlueChem supplies PolyDADMAC (CAS 26062-79-3) in liquid and powder forms with COA and SDS. See our PolyDADMAC buying guide, or contact our team for specifications, packaging and a quotation.
Cyclopolymerization: Why the Ring Structure Matters
PolyDADMAC is not a simple linear vinyl polymer – it forms through cyclopolymerization. The growing radical adds across one allyl group of the DADMAC monomer, then the second allyl group of the same molecule closes intramolecularly to form a pyrrolidinium ring, and the chain propagates. The consequences are practical:
- Nearly every repeat unit carries a ring, so the cationic charge is high and permanent – it does not depend on pH.
- Molecular weight is set by the initiator system (typically persulfate or a redox pair), monomer concentration and temperature, ranging from tens of thousands to several hundred thousand Daltons.
- Residual monomer is controlled by running to high conversion and stripping – which is why the specification sets a residual DADMAC limit.
This ring-forming mechanism is what separates PolyDADMAC from polyamine and from cationic PAM: it delivers a very high charge density on a relatively low-molecular-weight backbone, which favours charge neutralisation over bridging.
PolyDADMAC vs Other Cationic Polymers
| Aspect | PolyDADMAC | Cationic PAM | Polyamine |
|---|---|---|---|
| Charge density | Very high, pH-independent | Medium | High |
| Molecular weight | Low to medium | High to very high | Low to medium |
| Primary mechanism | Charge neutralisation | Bridging | Charge neutralisation |
| Drinking-water acceptance | Widely approved | Grade-dependent | Less common |
| Typical role | Primary coagulant / anionic trash catcher | Flocculant aid | Conditioner / coagulant |
In practice PolyDADMAC and polyamine are often interchangeable as primary coagulants; which performs better depends on the water chemistry. For selection guidance see our comparison of polyamine vs PAM vs PolyDADMAC.
Comparing Grades: What Actually Matters
PolyDADMAC is produced by a number of established manufacturers worldwide, and their product lines set the usual reference points for charge density, molecular weight and purity. When comparing any PolyDADMAC – including Chinese-manufactured grades – these are the checks that matter:
| Check | Why it matters |
|---|---|
| Solids content | Sets the active dose and the freight cost per tonne of active polymer |
| Viscosity grade | Reflects molecular weight; affects mixing, pumping and bridging behaviour |
| Residual monomer (DADMAC) | Purity and safety control; critical for drinking-water grades |
| Charge density | Determines the dose needed to neutralise a given colloidal charge |
| Jar-test performance on your water | The only reliable predictor – same water, same test conditions |
Because the chemistry is standardised, the practical differences between suppliers show up in these five checks and in batch-to-batch consistency – not in the headline description.
Automation, Sludge and Environmental Notes
- Automated dosing – modern plants adjust the PolyDADMAC feed in real time using streaming-current or UV254 signals, holding the residual charge in a target window while minimising consumption.
- Lower sludge – as an organic high-charge coagulant it does not create the metal-hydroxide sludge that alum or ferric salts do, and the dose per unit of charge neutralised is small – both of which matter for plants reporting on sludge disposal and sustainability targets.
- Handling – supplied as a viscous aqueous solution; dilute before dosing, use corrosion-resistant equipment, and avoid bringing concentrated anionic polymer solutions into direct contact with it.
13. References and Further Reading
- PubChem and standard polymer references for poly(diallyldimethylammonium chloride), CAS 26062-79-3.
- NSF/ANSI 60 (Drinking Water Treatment Chemicals – Health Effects) certification scheme information.
- Manufacturer technical literature on PolyDADMAC grades, viscosities and coagulation applications.
Disclaimer: This article is provided for technical and informational reference only and does not constitute regulatory, legal or engineering advice. Dosing and application decisions should be based on jar testing and on the requirements of the specific water or process, and applicable drinking-water regulations should be observed.
PolyBlueChem supplies PolyDADMAC (CAS 26062-79-3) as liquid and powder grades with a full Certificate of Analysis. For specifications, a quotation or documentation, contact our team.
Related reading
- Flocculant selection chart: PAM vs PolyDADMAC vs polyamine by charge and application
- Water treatment chemicals overview: coagulants, flocculants, biocides and dechlorination
- PolyDADMAC in Drinking Water Treatment: Coagulation and NSF Standards
- PolyDADMAC in Papermaking: Anionic Trash Catcher and Retention
- How to Buy PolyDADMAC: Specs, COA and Grade Selection
- Polyamine vs PAM vs PolyDADMAC: Choosing the Right Organic Flocculant
- PolyDADMAC (CAS 26062-79-3) – product page