Polydiallyldimethylammonium chloride (shortened polyDADMAC or polyDDA), also commonly

polyquaternium Polyquaternium is the International Nomenclature for Cosmetic Ingredients designation for several polycationic polymers that are used in the personal care industry. Polyquaternium is a neologism used to emphasize the presence of quaternary a ...

-6, is a homopolymer of diallyldimethylammonium chloride (DADMAC). The molecular weight of polyDADMAC is typically in the range of hundreds of thousands of grams per mole, and even up to a million for some products. PolyDADMAC is usually delivered as a liquid concentrate having a solids level in the range of 10 to 50%. It is a high charge density cationic

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

. The charge density makes it well suited for

flocculation In colloidal chemistry, flocculation is a process by which colloidal particles come out of Suspension (chemistry), suspension to sediment in the form of floc or flake, either spontaneously or due to the addition of a clarifying agent. The actio ...

. Actually, pDADMAC or DMDAAC, is used as a coagulant - a charge neutralization process that precedes flocculation.

History

PolyDADMAC polymers were first prepared and studied in 1957 by Professor George Butler at the University of Florida. It was remarkable as it was soluble in water in contrast at the time to other known synthetic polymers formed by polymerization of monomers containing more than one vinyl functionality. The structure and reaction path was determined in 2002 with

NMR Nuclear magnetic resonance (NMR) is a physical phenomenon in which atomic nucleus, nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near and far field, near field) and respond by producing ...

studies. Much of what we know about pDADMAC in water treatment and personal care is from Jerry Boothe of Calgon Corporation.

Synthesis

The monomer DADMAC is formed by reacting two equivalents of

allyl chloride Allyl chloride is the organic compound with the formula C H2=CHCH2 Cl. This colorless liquid is insoluble in water but soluble in common organic solvents. It is mainly converted to epichlorohydrin, used in the production of plastics. It is a c ...

with

dimethylamine Dimethylamine is an organic compound with the formula (CH3)2NH. This secondary amine is a colorless, flammable gas with an ammonia-like odor. Dimethylamine is commonly encountered commercially as a solution in water at concentrations up to around ...

. PolyDADMAC is then synthesized by radical polymerization of DADMAC with an organic

peroxide In chemistry, peroxides are a group of Chemical compound, compounds with the structure , where the R's represent a radical (a portion of a complete molecule; not necessarily a free radical) and O's are single oxygen atoms. Oxygen atoms are joined ...

used as a

catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

. Two polymeric structures are possible when polymerizing DADMAC: ''N''-substituted

piperidine Piperidine is an organic compound with the molecular formula (CH2)5NH. This heterocyclic amine consists of a six-membered ring containing five methylene bridges (–CH2–) and one amine bridge (–NH–). It is a colorless liquid with an odor de ...

structure or ''N''-substituted pyrrolidine structure. The pyrrolidine structure is favored. :

Applications

Effluent treatment

PolyDADMAC is used in waste water treatment as a primary organic coagulant which neutralizes negatively charged

colloid A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others exte ...

al material and reduces

sludge Sludge (possibly , or some dialect related to slush) is a semi-solid slurry that can be produced from a range of industrial processes, from water treatment, wastewater treatment or on-site sanitation systems. It can be produced as a settled sus ...

volume compared with

inorganic An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''. Inor ...

coagulants.

Pulp and paper industry

PolyDADMAC is used for controlling disturbing substances in the

papermaking Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is Pulp and paper industry, made using industrial machinery, while handmade pape ...

process. It provides superior fixing of pitch from mechanical pulp and of

latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latices are found in nature, but synthetic latices are common as well. In nature, latex is found as a wikt:milky, milky fluid, which is present in 10% of all floweri ...

from coated broke. Used in the short circulation of a

paper mill A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags, and other ingredients. Prior to the invention and adoption of the Fourdrinier machine and other types of paper machine that use an endless belt ...

to enhance retention and dewatering. In addition, it can be used to improve the efficiency of disk filters and flotators, and for cationization of fillers to provide maximal filler retention.

Water purification

PolyDADMAC is used as a coagulant in

water purification Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for hu ...

. It is effective in coagulating and flocculating inorganic and organic particles such as silt, clay, algae, bacteria and viruses. At high concentrations the organic polymer can remove natural organic matter such as humic and fulvic acids resulting in fewer disinfection byproduct precursors and less color.Edzwald, James K., ed. (2011). ''Water Quality and Treatment.'' 6th Edition. New York:McGraw-Hill. p. 8.64.

References

{{reflist Organic polymers Quaternary ammonium compounds Water treatment