Polydiallyldimethylammonium chloride (shortened polyDADMAC or polyDDA), also commonly polyquaternium-6, is a

homopolymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic an ...

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 (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

. The charge density makes it well suited for

flocculation Flocculation, in the field of chemistry, is a process by which colloidal particles come out of suspension to sediment under the form of floc or flake, either spontaneously or due to the addition of a clarifying agent. The action differs from ...

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 studies.

Synthesis

The monomer DADMAC is formed by reacting two equivalents of allyl chloride 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 arou ...

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

peroxide In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable. The most common peroxide is hydrogen p ...

used as a

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

. 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 Pyrrolidine, also known as tetrahydropyrrole, is an organic compound with the molecular formula (CH2)4NH. It is a cyclic secondary amine, also classified as a saturated heterocycle. It is a colourless liquid that is miscible with water and most ...

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 Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons resp ...

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 extend ...

al material and reduces

sludge Sludge 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. For example, it can be produced as a settled suspension obtained from conventional ...

volume compared with

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

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 made using industrial machinery, while handmade paper survives as a speciali ...

process. It provides superior

fixing Fixing may refer to: * The present participle of the verb "to fix", an action meaning maintenance, repair, and operations * "fixing someone up" in the context of arranging or finding a social date for someone * "Fixing", craving an addictive drug, ...

of pitch from

mechanical pulp Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw mate ...

and of

latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well. In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosperms ...

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 Dewatering is the removal of water from a location. This may be done by wet classification, centrifugation, filtration, or similar solid-liquid separation processes, such as removal of residual liquid from a filter cake by a filter press as p ...

. 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