Although PDMDAAC has a high density of positive charge, it also has some shortcomings, such as low molecular weight due to factors such as decay chain transfer, and its strong hydrophilicity and hydrophobicity. These disadvantages limit its application to a certain extent. In order to give full play to its performance and make full use of its advantages of high efficiency, non-toxicity and low price, researchers have taken many measures to improve its performance, summarized as follows:

(1) Copolymerize with active monomers to increase molecular weight. The common comonomer is acrylamide (AM). The molecular weight of P (DMDAAC/AM) can easily reach more than one million, while PDMDAAC is more difficult. In the aspect of water treatment, the increase of molecular weight helps to enhance the adsorption and bridging function of the polymer, but the increase of molecular weight is accompanied by the decrease of the content of DMDAAC in the copolymer, that is, the decrease of the cationic degree, which affects the electric neutralization performance of the polymer. This contradiction prompted many researchers to do a lot of work to find the best molecular weight and the best cationic degree, so as to achieve the best performance of the polymer.

In addition, we should also consider from another aspect, that is to look for active cationic monomers to copolymerize with DMDAAC to increase the molecular weight without reducing the cationic degree. This aspect is often limited by production costs, resulting in less application.

(2) Introduce hydrophobic structure and rigid structure. There is a direct relationship between polymer properties and structure. The introduction of hydrophobic structure into DMDAAC polymer will change its properties. For example, the polyelectrolyte effect is weakened, and the viscosity decreases with the change of concentration. In addition, in the water treatment method, the hydrophobic group of the polymer can associate with the hydrophobic oil drops or dyes and other organic substances. In addition to the electric neutralization of DMDAAC itself, the flocculation effect will be significantly improved in terms of oil removal, decolorization, and turbidity removal, thus solving the treatment problem of organic colored wastewater (such as oily wastewater and printing and dyeing wastewater) that is difficult to be biodegradable. There are two ways to introduce hydrophobic structure: one is the copolymerization of DMDAAC and hydrophobic monomer; The second is to replace one or two methyl groups on the N atom of DMDAAC with hydrocarbon groups with larger carbon atoms. Of course, this monomer is no longer DMDAAC, but in order to expand the performance of the polymer, we might as well try.

The introduction of rigid structure into the polymer will make the volume of the polymer large, which is conducive to improving the flocculation performance of the polymer. The introduction of rigid structure is also conducive to improving the salt resistance of the product, so that the effective molecular weight of the polymer will not be reduced due to the presence of a large amount of salt during application.

Many groups are both hydrophobic and rigid. Therefore, in many cases, the introduction of the two not only does not contradict, but also can complement each other.

(3) Used in combination with other chemicals. When DMDAAC polymer, especially homopolymer, is used alone, sometimes the effect is not very good. However, it can achieve good results when combined with other chemical agents (organic or inorganic). For example, if PDMDAAC is used alone, the effect of clay swelling prevention is not obvious, but if it is used in combination with appropriate admixture, the static effect of clay swelling prevention can reach 95%~100%. For another example, when DMDAAC polymer is used as an organic polymer flocculant to treat water, if it is combined with inorganic flocculant, it will complement each other's advantages, not only improve the flocculation effect, but also reduce the treatment cost. This is particularly important for some DMDAAC flocculants with low cationic degree and high molecular weight.

Through the above measures, the application performance of DMDAAC polymer has been expanded and the application range has been wider.

Related product: Poly(Dimethyl diallyl ammonium Chloride) Series