PolyDADMAC

PolyDADMAC
Other names Poly(dimethyldiallylammonium chloride)
Identifiers
CAS number	26062-79-3
Properties
Molecular formula	(C8H16NCl)n
Molar mass	variable
Solubility in water	soluble
Hazards
R-phrases	R52/53
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Polydiallyldimethylammonium chloride, or shortened polyDADMAC 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. The charge density makes it well suited for flocculation.

Synthesis

The monomer DADMAC is formed by reacting two equivalents of allyl chloride with dimethylamine. PolyDADMAC is then synthesized by radical polymerization of DADMAC with an organic peroxide used as a catalyst. Two polymeric structures are possible when polymerizing DADMAC: N-substituted piperidine structure or N-substituted pyrrolidine structure. The pyrrolidine structure is favored.^[1]

Polymerization of PolyDADMAC (shown as favoured pyrrolidine structure)

Applications

Effluent treatment

PolyDADMAC is used in waste water treatment as a primary organic coagulant which neutralizes negatively charged colloidal material and reduces sludge volume compared with inorganic coagulants.

Pulp and paper industry

PolyDADMAC is used for controlling disturbing substances in the papermaking process. It provides superior fixing of pitch from mechanical pulp and of latex from coated broke. Used in the short circulation of a paper mill 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.

PolyDADMAC can also be used as a flocculant to improve soap separation process in the evaporation plant of kraft pulp mills thus contributing to higher tall oil yield.

Water purification

PolyDADMAC is used as flocculant in water purification. It is very effective in flocculating, decoloring, killing algae and removing organics such as humus. Little is needed to produce large flocs, rapid precipitation and low turbidity residue.

References

1. ^ John, Wilson; et al. (2002), Structure and Properties of PolyDADMAC for Water Purification, http://academic.sun.ac.za/unesco/Conferences/Conference2002/JohnP.pdf