The Influence of Dispersant Structure on its Dispersibility Performance

R groups (polymer chains): The most common R groups are polyisobutylene (PIB). The molecular weight (Mn) of the polymer has a significant impact on dispersibility.

R groups (polymer chains): The most common R groups are polyisobutylene (PIB). The molecular weight (Mn) of the polymer has a significant impact on dispersibility. Both excessively high and low molecular weights are not conducive to dispersibility, hence, the molecular weight of dispersants is typically concentrated between 3000-7000. Higher molecular weights have a positive effect on improving dispersibility, but overly long chains can affect low-temperature properties, which requires a comprehensive consideration. Additionally, the polydispersity index (PDI, i.e., Mw/Mn) is also an important parameter for assessing the dispersibility characteristics of PIB. A lower PDI indicates that the polymerization degree of the polymer is closer to that of a pure substance, resulting in better dispersibility.

Anchor groups: Conventional dispersants usually have one anchor group, while double-hang dispersants have two. The role of the anchor group is similar to the handle of a broom, stabilizing the broom head in front, and it has a significant impact on dispersibility. For example, Mannich base dispersants are obtained through the Mannich reaction, which replaces maleic anhydride as the connecting body, possessing a certain polarity, but not too strong.

Polar ends: The polar end is the core part of the dispersant, with common polar ends including polyethylene polyamines. Since sludge or oxidation products are usually acidic, dispersants containing N (alkaline) help adsorb these substances. Different polar ends have a significant difference in selectivity for different substances, therefore, different types of engines require different types of dispersants.

In summary, the dispersibility of dispersants is closely related to the molecular weight of their R groups, polydispersity index, anchor groups, and the structure of the polar ends. These factors collectively determine the performance of dispersants, which in turn affects their dispersing effects in different applications.