1. Introduction of PolyDADMAC, CAS :26062-79-3
Poly(diallyldimethylammonium chloride), commonly known as PolyDADMAC (also abbreviated as PDMDAAC or PDADMAC), is a water‑soluble cationic polyelectrolyte of considerable importance across various industries. The polymer is formed from the monomer diallyldimethylammonium chloride (DADMAC), arranged in a repeating unit form: (C₈H₁₆NCl)ₙ, with variations in molecular weight ranging from low (≈ <100,000) to high (up to ~1,000,000) depending on grade and manufacturer
2. Chemical and Physical Properties
2.1 Physical Appearance & Solubility
- In liquid form, PolyDADMAC typically appears as a colorless to light yellow viscous liquid, with a freezing point around –2.8 °C, and boiling/decomposition point between 280–300 °C, depending on specific grade.
- In powder form, it tends to be white to light yellow beads or flakes, also soluble in water, non‑flammable, and hydrolytically stable.
2.2 Density, Viscosity & Optical Properties
- Density of aqueous solution forms lies typically in the ~1.03–1.09 g/cm³ range at 20–25 °C.
- Viscosity varies widely with concentration and molecular weight: 60–180 cP for ~20 wt.% solutions, rising to several thousand cP for higher viscosity grades.
- Refractive index: n²⁰_D around 1.375–1.417 depending on concentration and grade.
2.3 Chemical Stability & Safety
- PolyDADMAC is generally stable, showing strong resistance to hydrolysis and oxidation, effective across broad pH ranges, and resistant to chlorine – attributes that enhance its usability in water treatment contexts
- Flammability is low or negligible; flash points exceed 100 °C.
- As a cationic polymer, PolyDADMAC carries a high positive charge density—an essential quality enabling coagulation/flocculation mechanisms.
- It should be stored in sealed, cool, dry, and dark conditions, away from strong oxidants
- While generally non‑toxic, handling precautions (gloves, eye protection, dust mask) are recommended
3. Synthesis and Polymerization
3.1 Monomer Synthesis
PolyDADMAC is synthesized via radical polymerization of DADMAC. The monomer itself is produced by reacting dimethylamine with two equivalents of allyl chloride.
3.2 Polymerization Process
- Radical polymerization typically employs organic peroxide catalysts to induce polymer growth.
- Polymer chain structures may follow two possible cyclization routes, favoring formation of N‑substituted pyrrolidine rings over piperidine rings.
- Resulting molecular weights vary from low (≈ <100,000) to higher ranges (200,000–1,000,000), depending on polymerization conditions and grade.
4. Industrial Applications
PolyDADMAC is used across a broad range of industries thanks to its cationic nature, high charge density, and stability. Below are key sectors and detailed roles.
4.1 Water and Wastewater Treatment
4.1.1 Coagulant/Flocculant
As a primary organic coagulant, PolyDADMAC neutralizes negatively charged colloidal particles (e.g., silt, clay, algae, bacteria, viruses), facilitating their aggregation and removal, improving clarity in water treatment – both drinking water and industrial wastewater.
4.1.2 Sludge Dewatering
The polymer aids sludge volume reduction, enabling efficient water separation and filtration operations
4.1.3 Removal of Natural Organic Matter
At higher concentrations, PolyDADMAC can remove humic and fulvic acids, lowering color and reducing disinfection by‑products during water treatment .
4.1.4 Textile Dye Wastewater Decolorization
Employed in dye and textile industries to decolorize and flocculate colored waste, especially effective against active, acidic, and disperse dyes .
4.2 Pulp and Paper Industry
- Enhances retention and drainage, promoting removal of fine particles and fillers.
- Improves disc filters, flotators, and filler cationization, thus strengthening paper and improving manufacturing efficiency .
- Provides fixing action, binding pitch from mechanical pulp and latex from broke (recycled fiber), improving product quality
4.3 Oilfield and Drilling Applications
- Acts as clay stabilizer in drilling fluids.
- Functions as cationic modifier in acid fracturing, aids water injection processes.
- Helps in oil–water separation, improving efficiency in hydrocarbon recovery .
4.4 Textiles & Dye‑Fixing Agent
Used as a formaldehyde‑free fixing agent, enhancing dye adherence in textile finishing while minimizing harmful chemical emissions .
4.5 Personal Care and Cosmetics
PolyDADMAC serves as a conditioning agent, antistatic agent, and humidifying agent in shampoos and skin lotions, improving texture and reducing static – often marketed as safe and formaldehyde‑free .
4.6 Other Chemical and Industrial Uses
- Functions as an emulsifier, antistatic agent, or surface active agent in various chemical formulations .
- Used in mineral processing as flocculant in mining operations (coal, gold, diamonds) to aid solid–liquid separation.
- In sugar and juice industries, acts as decolorant .
- Functions in coatings and inks for color binding, anti‑corrosion, or polymer bridging applications .
4.7 Nanotechnology, Sensors & Biomedical Uses
- Used to stabilize nanoparticles (e.g. copper hexacyanoferrate nanoparticles), preventing aggregation and controlling size distribution .
- Serves as a substrate modifier in biosensor and chemical sensor fabrication (e.g. modifying indium tin oxide, ITO, or catalyst platforms for L‑cysteine detection) .
- Used in drug delivery systems, surface‑coating gold nanorods to enhance cellular uptake, or forming responsive carriers with mesoporous silica .
5. Summary Table
| Aspect | Key Highlights |
| Formula/CAS | (C₈H₁₆NCl)ₙ; CAS 26062‑79‑3; synonyms: PDADMAC, PDMDAAC |
| Physical Forms | Liquid (viscous pale yellow) & Powder (beads/flakes) |
| Density / Viscosity | ~1.03–1.09 g/cm³; viscosity depends on concentration and Mw |
| Optical Properties | Refractive index ~1.375–1.417 |
| Stability | Hydrolytically and thermally stable (decomp. >280 °C), chlorine‑resistant, wide pH range |
| Synthesis | Radical polymerization of DADMAC (produced from allyl chloride + dimethylamine) |
| Charge & Mechanism | High cationic charge density for coagulation/flocculation |
| Key Applications | Water treatment (drinking and wastewater), sludge dewatering, dye decolorization, pulp & paper processing, textile dye fixation, oilfield drilling, personal care, nanoparticle stabilization, sensors, drug delivery, mining, sugar/juice refining etc. |
6. Conclusion
Poly(diallyldimethylammonium chloride) is a versatile, cationic polyelectrolyte valued for its robust stability, high charge density, and adaptability across a remarkable range of industrial processes. From its role as a key flocculant in water and wastewater treatment, to improving paper retention, enabling textile dye fixation, functioning in oilfield and mining operations, enhancing personal care products, and supporting innovations in nanotechnology, sensors, and biomedicine—PolyDADMAC is a cornerstone polymer.
The ability to tailor its molecular weight, viscosity, and form (liquid vs powder) allows manufacturers to align the polymer precisely with application requirements. Its formaldehyde‑free nature and regulatory compatibility further boost its industrial appeal.
As water treatment, sustainability goals, and advanced material technologies continue to evolve, PolyDADMAC remains a vital tool—delivering performance, adaptability, and reliability across diverse sectors.